Do They Work — API Quick Start VS Tetra SafeStart?

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There’s an ongoing debate among fishkeepers about whether Tetra’s SafeStart and API’s Quick Start even work.

Soo many products, but which ones work?

What is the difference between Tetra SafeStart and Tetra SafeStart Plus anyway?

Starting a new tank can be stressful for both you and your new fish buddies.

The logic behind these products is solid, but that’s in theory.

Is there a safe dose or an overdose?

Should you do a fishless cycle?

What’s the reality? The good news is I have tested them both…twice.

I’d be more than happy to show you my results and point you in the right direction.

Shall we?

Main differences – API Quick Start versus Tetra SafeStart Plus?

api quick start vs tetra safestart header

Both products claim to have live nitrifying bacteria that will speed up or reinforce your nitrogen cycle.

They contain two stains of beneficial nitrifiers – one that turns the ammonia into nitrites and one that turns said nitrites into harmless nitrates.

Here’s the truth about the Tetra SafeStart vs API Quick Start comparison:

The difference between the two products is that API Quick Start can be used in both freshwater and saltwater aquariums whereas Tetra SafeStart can only be used in freshwater systems by design. These aquarium cycle starters also contain slightly different strains of bacteria, which affects how fast each product works.

Both Tetra Safe Start and API Quick Start will work, given that they are applied in a correct manner. The cycling of a new tank will speed up significantly but it won’t happen overnight.

Generally speaking, with proper use you can realistically expect to wait about 14 days to fully cycle a fish tank with API Quick Start. Tetra SafeStart takes about the same time although often it may finish the process in just 10 days. Dosage plays a major role in success.

Unfortunately, following the instructions on the back is not something that will help, as they are pretty vague.

After experimenting hard I’ve managed to highlight what strengthens your chance for success, eventually finding a process that, in my opinion, is foolproof.

I ran two tests on both before actually using them in a real fish tank project.

The only disappointing part is that they will not cycle your fish tank the same day.

Also, by the “add fish instantly” on the label they don’t mean all the fish the tank can hold but rather just a couple, until the beneficial bacteria settle.

Both API Quick Start and Tetra SafeStart can be added with live fish in the tank.

The bottles obviously don’t contain substrances harmful to fish, just the opposite.

How to use them and make them work?

After running a couple of tests I am confident to share my success formula with you.

Going through hundreds of forum threads and speaking with fishkeepers I know, I did find confirmations of my findings.

This means that my logic was correct.

Tetra SafeStart Plus

Firstly you’d need to get the right bottle of bacteria.

by Cczman

Safe Start and Quick Start both contain live “inactivated” bacteria. By being inactivated like this the products last longer on the shelf and are easier to store, which makes them more beginner-friendly.

Both brands are claiming no refrigeration is needed.

The perfect temperature for the bacteria’s shelf and in-water life would be between 40°F and 80°F (5°C to 25°C).

Going beneath or above that range may spoil it, by killing the microorganisms and rendering the product useless.

Trusting your local fish store is okay, but I do prefer getting mine over at Amazon (link that will open in a new tab).

Anyway, if you do insist on getting the bottles from your local market make sure that they were safely stored and aim to get the most recently shipped ones (with the farthest expiration date).

Some instructions before you start are:

  • Get a bottle that has been manufactured as recently as possible – The newer the bottle, the better. Also, get at least two bottles, I will explain why later.
  • Choose a bottle meant for a larger aquarium than yours – For me, it worked best when I used the 3.38 Oz bottle of Tetra SafeStart Plus for my 20 gallons, and also when I doubled the dose recommended for the API Quick Start.
  • Make sure the ammonia is not already deadly high – everything above 2.5 ppm of ammonia will be harmful to your fish AND the bacteria. Before you start with the nitrogen cycle you need the ammonia lowered as much as possible.

With that out of the way, you can start cycling your aquarium.

Follow these exact steps to properly use Tetra SafeStart or API Quick Start:

  1. Dechlorinate your water no less than 24 hours before adding the bacteria.

    Use a commercial dechlorinator.

    Leave the filters running during that time.

    Chlorine will kill the not well-established cycling bacteria. Also, when having live fish in the tank you first dechlorinate the water and then add it to the tank.

  2. Shake the bottle of bacteria hard.

    This part is really important.

    Shake the bottle really well before adding the bacteria.

  3. Pour in double the recommended dosage.

    For Tetra SafeStart users just add the WHOLE bottle of bacteria to your aquarium.

    Add it all.

    You can’t overdose with aquarium cycle starter products, unlike with dechlorinators and other water conditioners.

    It’s simply beneficial bacteria. The more the better.

  4. Add 1 SMALL fish per 10 gallons of water.

    Adding fish to your new tank should be done shortly after you’ve poured in the bacteria, within a maximum of 2 hours.

    This proportion of fish-to-volume of water is what worked best for me.

    By definition, this is where most people make a mistake and end up with dead fish in their new aquarium.

    Adding just one small fish per 10 gallons of water is the safest way of controlling the ammonia levels. Here you can find some hardy beginner fish options.

    If you’re cycling a 5-gallon tank it’s really best to put a source of ammonia in it and no live fish. Such source could be fish food.

    Anyway, it’s technically true that you can stock the tank up, but you’d need very clean fish (ones that do not poop as much) and you’d have to feed them very carefully to either not overfeed (leaving extra ammonia work for your bacteria) or starve them (being too cautious not to overload your tank with ammonia).

  5. Feed your fish every other day.

    Test your water frequently, if you notice a spike in ammonia it’s okay to not feed your fish that day.

    Many fish can survive more than a week without food, so they will be fine.

  6. Don’t do water changes until the 14th day.

    If and only if the ammonia starts rising for no apparent reason you can do a water change to lower the levels down.

    Add another bottle of the product if that happens.

    This is why I told you to get a second bottle.

    However, there’s another solid reason behind this point.

    You’re probably using chlorinated tap water for your fish tank. In order to perform a water change you’d need to dechlorinate the water first, right?

    Water facilities in the more developed cities use Chloramine instead of Chlorine for disinfection.

    Chloramine represents the chemical bond between chlorine + ammonia.

    Seachem Prime

    Seachem Prime (a commonly used dechlorinator), for example, breaks down chloramine to chlorine and ammonia, takes care of the chlorine, and detoxifies the released ammonia.

    by JustSuppThings

    Every product that claims to detoxify ammonia likely transforms it into ammoniUM.

    Ammonium is harmless to bacteria and fish alike, but the detoxifying effect only lasts for 24 to 48 hours if your tank’s pH is above 7.0. This does not mean that having more than 7.0 pH is bad, it just means that using ammonia detoxifiers in a non-cycled tank is not a good long-term solution.

    Anyway, after that, the ammonium turns back into ammonia, which means you now have more of the latter in the cycling aquarium.

    The more Chloramine your water facility uses, the more the released ammonia after the effect of the detoxifier expires. This could consequently harm your bacterial biofilter and fish if the contents turn out to be too high for the bacteria to handle in time.

    Author’s note: This only affects new aquariums that do not have an established colony of nitrifying bacteria.

    Anyway, another argument for not changing the water in the first 14 days of cycling (unless there’s a dangerous ammonia spike out of nowhere) is that studies suggest that nitrifying bacteria use ammonia instead of ammonium for their source of energy.

    Continuously using a dechlorinator that turns ammonia into ammonium could actually slow down the nitrogen cycle in your aquarium even further. The nitrifying bacteria would not be interested in the latter and will not be stimulated to multiply further.

    This can easily turn into a vicious circle and a never-ending supply of Prime for a new, non-cycled fish tank…

    If you’re using bottled bacteria you’d want your fish tank to cycle as soon as possible, right?

    Tip: The best way to avoid all of this is by having a separate batch of dechlorinated water to use for water changes during aquarium cycling. The “emergency batch” should be dechlorinated at least 24 hours before use. Add a little bit of bottled bacteria to it to make up for the residual ammonia and it’s good to go.

    Suggested Read: How Aquarium Fish could Die After a Large Water Change

    Despite the described scenario Seachem’s Prime still remains a fantastic option for water dechlorination in a fully cycled aquarium. I’d recommend it to anyone who is using tap water for their aquarium. The residual ammonia from breaking down the Chloramine would be negligible to the already-established bacterial colony in a mature tank.

    Anyway, after 14 days of cycling, you can perform a water change the regular way.

  7. Don’t test the water for the first 2 days.

    It’s okay to test it whenever you want but that is something that I stuck with throughout my tests.

  8. Turn the UV lights off for the first day or two.

    Ultraviolet light does affect the bacteria in a negative way.

    For it to successfully establish I’d strongly recommend not turning those lights on the first day after the application (if you have them).

Keeping the fish tank cycled

After the second week you can gradually add fish, but of course, don’t add 10 at a time. This would overwhelm the bacteria.

When doing the first water change the ammonia may go up, as there may be some ammonia in tap water, but I wouldn’t worry about it that much.

The levels should be overall low and should quickly get back to normal within the next 12 hours or so.

Also, don’t freak out if you don’t see your nitrites spike when water testing.

Tetra SafeStart

If you’re using Tetra’s SafeStart the process will skip the nitrites building up and will directly build into nitrates.

by flexed_guitar

Don’t worry if your aquarium becomes cloudy at first.

The water will get clear within two to three days or a week at most.

Seeing cloudy water in a new aquarium at the beginning of its Nitrogen cycling is completely normal and it means that different bacteria are establishing their hierarchy.

Visit the link if you’d like to understand the process in depth. Understanding aquarium microfauna is, in my opinion, a core component of long-term success in fish keeping.

And that’s not an overstatement.

Which of the two should you choose? Which one is the best for your?

This is not one of those posts where I discuss the pros and cons of both products and leave the choice to you.

I have a statement:

Both can be (successfully) used for a start but If you’re starting a brand new empty fish tank and want to establish an environment safe from Ammonia, I’d recommend using Tetra SafeStart.

API Quick Start

If you’re starting a brand new planted tank, doing huge water changes, or adding a lot of fish at once to an already cycled planted tank I’d go for API Quick Start.

by Tobyracer

Tetra SafeStart’s better at handling the nitrites (it virtually skips them) and API Quick Start will normalize the ammonia levels in the water quicker. The latter is more important in a mature tank with many live fish in it.

High ammonia levels may result in your fish staying at the bottom of the tank seemingly gasping in despair (click the link for an in-depth explanation of this behavior in Bettas).

The API Quick Start is more efficient when you have a planted tank as it does not handle the nitrite levels as well as Tetra’s SafeStart. Live aquatic plants prefer ammonia and nitrite over nitrate as their source of nitrogen so, by using API’s product you will both speed up the cycle and let your plants feed on the nitrite.

Note: Between Tetra SafeStart and Tetra SafeStart Plus the difference is only in the concentration of the bacteria. I’m really happy with Using the Plus version, so the instructions will remain the same.

The alternative bottled bacteria for saltwater aquariums is called Bio Spira.

API doesn’t have a saltwater version, you just double the dose.

What’s with the mixed opinions then?

Honestly, it’s probably a human error.

Seeing how (upon proper use) the products kept proving themselves to me and others I spoke to, I can only conclude that.

Then again, the negative reviews pushed me to test them myself, before anything.


Fishkeeping is a hobby that requires some patience.

Whether you choose to go natural or use bottled bacteria products for starting a new fish tank, you will have to wait it out a bit.

There is no shortcut for that, there are only shorter cuts…

Tell me how things unfolded for your new aquarium in the comments.

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Momchil Boyanov is the Founder and now Senior Editor of AquAnswers. He has over 13+ years of experience in keeping home aquariums as well as providing professional aquarium services. Momchil has had his fair share of adventures in aquarium care. He has made MANY mistakes throughout his fishkeeping journey and thus learned A LOT. Through Aquanswers, Momchil shares knowledge about freshwater and saltwater aquariums with the people within this community.

390 thoughts on “Do They Work — API Quick Start VS Tetra SafeStart?”

  1. Thanks for the article! I re-read everything 5 times over now just to make sure I understood everything. Just started a 20 gal planted tank with two bottles of TSS+ and its been running for 4 days. Added two dwarf Gourami and they seem to be doing fine so far with the recommended feeding of every other day. I’ve just tested the water and got a reading of .25 ppm ammonia, 0 nitrites, and 40 ppm nitrates. Is this normal for the first couple of days? If not what should I do and look out for?

    Thanks again for writing this. Been a little scared to start into this hobby but your article has helped a great deal.

  2. Hey there I have been visitng your site countless times, this is great thank your or this article!

    I have tried fishless cycling for 3 months (with TSS+) and honestly, I can no longer wait, I’d rather do the water changes and testing with a fish in there. Many people have been condemning me on aquarist threads :/

    I plan on doing 100% water change today and adding a water wisteria tomorrow as well as a betta with TSS+ (they don’t have API quickstart near me).

    I have a 10 gallon tank. Do you think 1 betta is enough of a bioload though, I want to have some harlequin rasboras in the long run too, but I am hesitant to add them now as I don’t want to stress them out in a group of less than 5.

    Thank you so much!

    • Hi Ashley, thanks for being a “secret” fan for so long!

      To me, it seems like you have the perfect opportunity to perform the fish-in cycling flawlessly.

      In fact, I recommend using 1 small fish per 10 gallons of water with a fish-in cycle. And TSS+ is an excellent product nonetheless.

      Once the tank is completely cycled and the water tests start showing consistent, safe readings you can go ahead and add the harlequin rasboras AND SOME MORE TSS+. After that, it all comes down to monitoring and a water change here and there.

      It is way easier to “expand” an existing bacterial colony than to start one from ground 0.

      The Water Wisteria is both an excellent plant for your setup and a sneaky trick to keep the water stable and clean. Seems to me that you’ve done your homework!

      On another note – yes, I completely understand your online community experience. “Condemning” is, perhaps, the word I would use too. Nowadays, I only comment in forums, when someone posts my article and asks questions in there (or tries to debunk the info in them, like in this one).

      Truth is, however, that the “fish-in cycling bad!!” mantra will get parroted every time you mention it because online communities tend to have this weird hive-mind where no one really ever questions anything and there are a small number of “authorities” that everyone follows.

      This is, in my opinion, counterproductive at best, because this way no one gets encouraged to think or experiment on their own and there’s no progress in the hobby. 🙂

      If fish-in cycling is done properly you have nothing to worry about, really. You’re one of the very few people that are willing to go with/have the exact setup I’m recommending for doing so.

      I’ve already done it countless times with 0 fish losses, so there’s that.

      Hope this helps and gives you the courage to go ahead and do your thing.

      By the info you provided, I can tell that you’re a responsible person and have done quite the research already. Well done, IMO you have an above-average knowledge than most people who start an aquarium nowadays. Keep up the good work.

      – Momchil

  3. Hi,
    Thank you for your clear and informative website. After days of scouting the internet, it’s so refreshing to find an informational Aquarium site that is simple, reasonable, and doesn’t have a gross commercial bias. Well done!
    I was reading this article because a friend just moved away and gave me their son’s Betta fish. It is currently in a half-gallon tank (!) and after researching this I bought a five gallon setup which should be here next week.
    I had a few questions about when my new tank arrives if anyone has time to answer… I hadn’t heard of tank cycling before today, but obviously it is vital to fish health. I am trying to decide which is worse for the poor Betta: rushing the tank cycle process, or leaving it in the current half-gallon tank too long. Is there a happy medium that might involve, say, some Tetra Safe Start in combination with water/gravel from its old tank?
    Any suggestions that would facilitate and speed up the transfer from the half-gallon to the new tank would be appreciated!

    • Hi Alaina,

      I’m really glad the quality of my website made an impression. Thanks!

      Anyway, your thinking is correct. Adding both bottled bacteria and “old tank” substrate to the new tank will likely speed up the cycling process significantly! The old substrate likely has some bacteria inhabiting it, etc.

      The only thing you’d need to do while you wait for the new tank is changing the water of the 0.5-gallon daily. To avoid stressing the fish with the huge water changes (literally almost all the water) you should make sure the new water that’s going in the 0.5-gallon is similar in temperature to the old one. Avoiding temperature shock and maintaining a clean environment for the Betta should be your top concern at this point.

      Don’t forget to dechlorinate if you use tap water for water changes.

      Hope this helps and good luck! You seem like a responsible person.

      • Hi,
        Thanks so much for the very helpful reply! The tank setup will be here tomorrow so I can get started right away on the tank cycling. I’m so glad that the old tank substrate will speed up the process! Also thank you especially for letting me know what I can do for the poor fish in the meantime. Hopefully he will survive long enough to make it into his new tank!
        Another quick question if you felt like answering it: the above article suggests in step four to add one fish per 10 gallons of water within two hours of adding the SafeStart. (I might add that the new tank will only be 5 gallons.) Should I add the Betta this early, or wait 10-14 days until the tank has fully cycled? Thanks again for all the help!

        • Hi, again Alaina, thanks for reaching out again!

          In your case, I’d add the Betta to the new tank immediately after adding TSS+. You have the old tank substrate and the bottled bacteria backing you up. it should all be fine, and I’m assuming that the Betta is not super fat (and therefore messy) anyway.

          At first, you could feed him every other day to control waste build-up. He’ll be fine with this schedule. On the other hand, the transfer may stress him a little and he may refuse to eat at all. Eating healthy food is literally what makes or breaks the immune system of fish and though they can live for about 2 weeks without food it’s not good when it’s combined with stress. If he refuses to eat, you could get him some freeze-dried bloodworms (these are commercially available water flea larvae, not real worms) and if he STILL refuses to eat them, you could get “aquarium-grade” garlic in which to soak the bloodworms before offering. Betta fish are carnivores and bloodworms are one of the best possible foods for them anyway.

          Ok, just remember to monitor his feeding habits after the transfer, and do a water test here and there (I’d recommend doing one every day or every other day during cycling) to assess the quality of the water and see if the tank has been fully cycled.

          Sorry if this sounds like a lot of work or anything. Though fish are overall low maintenance house pets they do require some work!

          Good luck Alaina! Report back when everything is ready and done or ask away if you have more questions. I want this to work out

          • SUCCESS!
            I’m so sorry it took me so long to give an update, but I’m pleased to say that, no doubt thanks to all the helpful advice, my Betta fish is happily installed in his new tank. I cycled the tank with Tetra SafeStart per the directions in this article, and added substrate from the old tank as recommended. After acclimating him slowly, I finally added the fish to the tank. Despite the initial shock, he is now doing swimmingly and seems to really appreciate finally having enough space! That is one happy fish.
            Thanks so much again for all of the advice and enthusiasm that has helped me succeed as a first time fish owner, and keep up the good work on this very helpful website.

          • Thanks, Alaina, I’m very happy that everything worked out according to plan.

            Happy fish keeping, friend! 🙂


    I hope your still able to see comments. Ive been new to the aquarium game started 3 weeks ago and i had a failed attempt at using fluval bio boost. SO i added fish and went for a fish in cycle with just prime, as i had already seen ammonia go up and come down without any fish. There are now steady 0 readings on my ammonia and 0.25 to 0.5 ppm Nitrites. Ive been changing my ater (40%) whenever i get a 0.5 sometimes even on a 0.25 reading of Nitrites. 3 days ago idecided to hold off and see if it rose wny further which it didnt, ive been dosing with prime when i do get a reading no more than once every other day.
    My question is if i add a little TSS now would it benefit my situation and possibly boost my Nitrifying bacteria to deal with that nitrite reading i cant seem to shake. If i do do that would it mean i would also have to not change the water for 14 days?

    Thanks soo much, i hope i get an answer, been looking for a TSS Expert for the longest.


    • Hi K A,

      Thank you for your questions.

      Yes, adding TSS+ will definitely help with Nitrites.

      However, from what I gather it may be that Prime and changing water have held you back.

      Changing water exports ammonia and nitrite which are food for the beneficial bacteria and therefore prevent the colony from establishing faster.

      Prime “detoxifies” ammonia and nitrite. I don’t know about Nitrite, but it turns ammonia into ammonIUM (its ion form) which is harmless for fish and invertebrates. However, ammonIUM is not a preferred source of food for beneficial nitrifiers and they degrade it at a very slow pace. This significantly slows down the cycling of an aquarium.

      All of this made me realize I should do the following when cycling an aquarium with fish:

      1. Have 1 SMALL fish per 5 or 10 gallons. This way the ammonia release is controlled and there’s a way smaller chance of a spike.
      2. Dechlorinate the water 24 prior to pouring in the beneficial bacteria in it (as most dechlorinators also “detoxify” Ammonia and Nitrite, hence prevent bacteria from establishing quicker).
      3. Don’t do water changes while cycling. A water change is only allowed if there’s a serious ammonia spike (but Step 1 makes sure there aren’t any).

      Does this help? 🙂

      I get notified about comments and though not entirely possible, I do my best to reply to most all people.


      • OK I have 4 small fish 2 platys and 2 guppies both male and none at full size, i was advised to get around 4 o begin with by my LFS. \Ok so as im alredy sort of mid cycle if i now add the TSS and then follow your great steps in this article would you say that would be okay. Or should i expect a quicker turn around? Also would it still require a whole bottle considering the fish are already in situ?

        Thank youuuu!

        • Yes, go ahead and add some TSS and follow the steps. The aquarium will likely get cycled quicker, because, as you said, you’re already mid-cycle.

          The whole bottle would not harm, but I guess given the circumstances you could do 1/2 and still reap the benefits.

          You’re welcome buddy

          • I dechlorinate my water with prime will that be an issue, i tend to put it in the water and leave it for a day or 2 before putting in the tank. Just thinking if my levels get high would it only be water changes or could i also use prime to protect the fish?

          • In case of an emergency you could use it I suppose.

            You’re doing as you should with the chlorinator. I can see that you’ve done your research.

            Btw how many gallons does the tank hold?

          • My tank holds 15 gallons (57 litres) and has 4 small to medium fish 2 platys and 2 guppies

          • I would do it with just 4 guppies, but it seems to me that you can pull this off safely.

            Go ahead and pour in some TSS and report back in a few days. Keep your calm and monitor the aquarium parameters daily. You should be fine, IMO. Also, I approve comments manually, so don’t worry if they don’t appear immediately. 🙂

            Good luck, K A!

          • 🙂 thanks! I forgot to mention my tank is heavily planted and my tap water reads nitrates at 20ppm. Nitrotes 0.5ppm ammonia 0ppm. Would this make any difference?

          • Not likely. In fact, it’s good that you made the tank heavily planted so the plants could suck up some of the nitrates. Well done.

          • Great dosed half the TSS so will be monitpring over coming days. Thanks for all the help. SUPERSTAR

          • Will i be okay leaving the tank for two days or can i test and get reliable results sooner. Ive grown quite attached to my fish and am slightly worried for them.

          • Nah, test whenever, no problems.

            Make sure to test with a liquid test kit, as it’s a lot more accurate than strips.

          • Great i have one just did a test and nitrites at 0 and ammonia remains zero nitrates ever so slightly darrker ill give it a few days but this looks like an instant improvement.

          • That’s absolutely fantastic news!

            Do report back in a couple of days!

          • Ive left my lights off now for a day since adding the TSS when would be safe to turn them back on?

          • One day should be enough. If you have a customizable light, you can just tune down the “blue” or “UV” colors, and not turn the whole thing off.

          • I use LED lights do these omit UV im using Nicrew Planted / Classic lights for my tank. ive searhed up adn down and cant tell what aspects are UV as its full spectrum as i can tell RGB

          • They do have the blue diode so it’s possible that they emit some UV. However, the amount of UV they emit is likely not enough to stall the development of your bacteria, so you can keep them on as usual.

            What I mean in the article is to turn off your lights if they are the ones with special “violet UV” diodes or to turn off a UV sterilizer if you run one.

            You should be fine, mate.

          • 48 hours and the levels ae consistent 0 ammonia 0 nitrite 20 nitrate. Ive had my fish in situ for coming on 3 weeks now. Would you suggest waiting out the whole 2 weeks before adding new fish, im eager to get some corys in the mx!

          • HI, your tank now seems cycled.

            You can get new fish, but try not to add too many at once! The latter can overwhelm beneficial bacteria and cause an ammonia spike. Also, acclimatize new fish.

            Good luck!

          • Sorry i didnt mean to confuse but my fish have been in for 3 weeks my TSS has been in for 2 and a bit days. Just for clarification. Wow my spelling is atrocious looking back

          • hey dude. back again! all is going well added 3 albino corys and 5 cherry shrimp on Sat with a bit of TSS and all has remained stable!

            2 questions:
            1. when should i do my first water change? i put in half a bottle a week ago today and the additional fish with a lil more on Sat.
   long should i wait to add more fish i want to complete my corys with an additional 3 and more shrimps as i love watching them forage?

          • hey hey K A,

            1. Since your fish tank is relatively stable now, you can perform a water change. No need to wait. If your NitrAtes are shooting up above 15-20 ppm you should likely exchange a portion of the water. Don’t forget that changing too much water at once can stress your fish and shrimp. I prefer doing 2x 15% water changes, one in the morning and one in the evening (because I have work in between lol). If I am around at the house I do the water changes 1-2 hours apart.

            2. Give it like 3 or 4 days to see if things really are stable (no fluctuations in ammonia and nitrite).

            P.S. – shrimp are awesome little workers.

          • ok. cool thanks!

            ive just tested my dechlorinated tap water and nitrates are 40+ seems like the TSS lowered it somehow or maybe my filter did. Either way not looking forward to adding more nitrates.

          • Woah,

            That’s a lot! Are you located in the USA? (it’s ok if you don’t want to answer) I’m only asking because here in the US, the allowed maximum level of Nitrates in tap water is around 50 PPM and that’s not uncommon across the country.

            I’m likely repeating myself but… Floating aquarium plants are excellent Nitrate sponges. They also look super cool and make fish and shrimp feel more at home and reduce the overall stress in the tank etc. With tap water infused with that much Nitrates, you should likely consider getting some floaters. TBH, the best option for water changes is RO/DI water filter for aquariums, but you’re new to fish keeping and that’s more of a long-term investment.

          • im based in the UK
            i re tested and i got a 20 -30ppm my plants i think are reducing nitrates. so ill keep changes small as you say.

          • Hey again final question i think.
            With my filter and cleaning the sponge etc. How long should i wait as ive looked and its pretty clogged up with gunk at the moment. but i have held off due to the TSS being involved it has been 2 weeks since the first TSS dose and 4 days since i introduced some guppys and a little tipple of TSS for the load increase.

          • Hi KA

            Depends on how the water parameters are.

            Your tank is already cycled and is now much more stable. 4 days is enough time to see if the couple of fish you added would throw the aquarium off balance.

            If your water parameters show 0 ppm Ammonia, 0 ppm Nitrite, and some ppm Nitrate, then the fish tank is probably stable at its current bioload.

            Remember to rinse the filter with old fish tank water, or dechlorinated water. Don’t use water straight from the tap for this, as it’s chlorinated and it can hurt the biofilter bacteria.

            Happy fish keeping 🙂

  5. Hi! This Article has really reassured me that the fish-in cycle can be done properly. So far, Ive been struggling over the past month to get my 29 gal fishless cycled with zero results. After purchasing TSS, I found this article to help me prepare on how to properly use it.So I plan to get a few guppies or minnows to help me cycle, along with TSS, to prepare the tank.
    However, my question is, I plan to have 2 fancy goldfish in the tank. Will the minnows/guppies be able to properly prepare the tank for the goldfish bioload?

    • Hi, Gaby,

      Yes, I think it will be enough to kickstart a stable cycle. Only thing I would recommend is adding the goldfish 1 by 1 and monitoring the tank’s parameters for some time.

      Good luck and keep me posted 🙂

      • Thanks so much for your advice! For the past 2 days Ive had 3 zebra danios cycling the tank after adding the TSS. So far the levels are 0 Nitrite and 10ppm Nitrate. However my confusion is with the Ammonia. My liquid test kit says its at 2ppm Ammonia, but my Ammonia Alert says .05ppm. I’ve tested the alert and it works just fine. Am I getting false positives from the liquid test? And when should I expect it to start dropping? I know it may be too soon I just want to make sure the cycle is working correctly after many failed attempts.

        • Hi Gaby,

          First thing I can think of: Did you shake the bottle of the liquid test REALLY hard and for at least 1 minute?

          2. How did you test the Ammonia Alert?

          3. It really depends on the tank, but I would say between the 3rd day and the end of the first week you can expect it to drop (still, not an exact science and it’s a relative estimation).

          Regards, Momchil

          • Actually I dont usually shake the Ammonia test bottles because it wasnt mentioned in the instructions. Is that something I should be doing? I tested the ammonia alert by removing it from my tank and placing it over a bottle of concentrated ammonia. After a few minutes, it turned dark purple. In the tank, it stays at a grey-green for .05ppm.

          • Hi, You should shake the vial vigorously!

          • Oh Im so sorry I misunderstood your last reply! I do in fact shake the vial vigorously each time and for each test. I thought you meant the solution bottles oops! But yes I do always shake it and today I got a reading of (what I think) is 1ppm Ammonia, but my alert still says otherwise. I think I may have to wait it out but I have a feeling my liquid test may be picking up the bound ammonia as well, which is why its higher than my alert. Would I need to add any more TSS? Or is this just a waiting game? I greatly appreciate your responses and advice thank you!

          • Hi again, Gaby!

            For now – wait. You’re barely 4 days in the cycling. All seems completely normal. Adding more bacteria is never harmful though. Did you not use the whole bottle at first, by the way? Also, what’s the size of your tank? I’m assuming at least 20 gallons?

            The liquid test should be the most accurate test. Frankly, I can’t remember if it would also pick up the ammonium ion(NH4+), or just ammonia (NH3). I need to dig in, but that’s possibly why it shows a higher reading.

            It is also possible that the ammonia alert is not as accurate as the liquid test (which I’m fairly certain is the case, but I don’t know the error margin). The Ammonia Alert is super useful to tell us when something is off in the aquarium and should likely not be used for accurate assessments of the current ammonia levels.

            Makes sense?

          • Yes that makes sense! I have a 29gal tank and used a full 8.45oz bottle, which treats 50 gallons. You’re absolutely right, I’ll have to practice better patience 🙂 but as its my first time cycling its been a very daunting task and I really appreciate your advice! Thank you!

          • No probs,

            Keep doing your research and be patient! Every new fish keeper’s vice is impatience (personal observation AND experience). The fact that you’re reading stuff and investigating beyond the common advice means that you’re on the right track IMO. 🙂

            Good luck and happy fish keeping!

  6. hi,
    thank you for this well explained information on how to do the cycle correctly,and i’m planning to follow every step you mention.
    but before starting have a few questions i like to ask..

    i have a 10gal bare buttom tank which i believe wasnt correctly cycle before in it have 2 tiger barb and one of them i think have hex.which i think will not last any longer.and the other healthy one(hopefully), i have seperated him in a temporary container.
    lets say the sick one doesnt make it.i’m planning to cycle the tank properly this time .
    – before starting should i take out all the water , clean the tank , filter and everything
    – can i use the other healthy barb during this cycle
    – if i will use the api quickstart for this cycle, what size should i buy for my 10gal
    – should i also pour the whole bottlein the tank
    – you mention that after 14 days water change only if theres a spike of ammonia for no reason,how many % should i do

    sorry for so many questions.

    thank you

    • Hi, Peter,

      1. No that is not needed.
      2. You probably could use both bards, but make sure you are extremely careful with feeding…
      3. 4 oz Bottle would be more than enough
      4. I would say pour it all in, but if you don’t have another bottle at hand (in case of an ammonia spike), you can use 50% and leave the other 50% of the contents for later.
      5. 20 to 25% should be enough. I prefer 2 water changes of 15% though. One in the morning before work and one in the evening. It’s better for the fish that way.

      Hope this helps

      • hi momchil..
        thanks a lot, for that quick response,
        with regards to the disease hexamita..
        isnt it very contagious, and will stay in the water or filter or any thing inside the tank.
        just afraid that if i have a successful cycle this time , my new batch of fish will contract hexamita.

        thanks again

      • thanks for the quick response.

        the reason why i ask if i needed to clean everything before starting the cycle,
        – isnt hex disease will stay in the water or filter or any ornaments inside the tank.
        i.m just afraid that, yes i will have a successfully cycled tank but with disease water in it.
        – and like to ask again regarding your instuction of..
        “after 14 days do a water change..”
        should i add anti chlorine(prime) to the water


        • Hi, again Peter,

          At first, I did not read what the barb was sick with. I did some research on the disease and it seems to be caused by some sort of protozoan parasites, that may or may not be present in the fish gut all the time. It seems like these parasites only thrive when the fish is weakened by some sort of stress factor. This changes things a bit…

          Are you treating with metronidazole and vitamin-enriched foods? From what I read metronidazole is only effective against anaerobic bacteria, and nitrifying bacteria are aerobic. Therefore it may be that metronidazole will not affect the bacteria in the nitrogen cycle. You can use the healthy fish for the cycle and then add the one that has been recently treated. From what I’ve read if the fish are happy and have enough vitamins in their diet the disease should not manifest itself. If, however, they both start showing sings after some time you can likely treat both fish in the cycled aquarium without losing the beneficial bacteria. Makes sense?

          Onto your second question – After the nitrogen cycle is established you can dechlorinate right before adding the new water to the fish tank. If you need to change the water during the tank is cycling (say, you experience an unexpected ammonia spike) – just have a separate container for new aquarium water. Dechlorinate the water in the container 1 or 2 days before the water change and you should be fine.

          • thanks again for answering my inquires.

            few questions pop up in my mind..

            – you mention that before dosing with the bacteria ,ammonia must not be high or it will kill the bottle bacteria, does this mean i have to have some reading of ammonia before dosing the bacteria to the tank? because right now my ammonia is 0

            – or after putting new water to the tank, dechlorinate , wait for 24hours or more, and just dose the bacteria in the tank,
            after, within 2 hours i should put the fish in?

            – my temperature is constantly at 83
            even with out a heater, is that good?


          • Hi, again Peter 🙂

            I don’t mind questions, it means you guys want to learn, which I think is good.

            1. Not necessarily. The fish will start producing ammonia to feed the bacteria.

            2. That’s how I recommend doing it.

            3. 83 is perfect for a tropical fish tank. I would toss a self-regulated heater in there if I’m expecting temperature fluctuations of some sort. Temperature fluctuations are in my experience one of the main reasons for a weakened immune system in fish, and therefore unexplained illness. The more stable the temp is the less shock for your fish. 🙂

            Good luck, and ask away or use the search bar if you have more questions (I may have something answered here)

          • hi monchil,

            thanks for your asap replies..

            i have done ur step 1-4, 18hours ago,

            step 5 1 hour ago

            test the water
            ammonia 0
            nitrite 0
            nitrate 0
            ph 7.8

            – is this normal?

            – from your experience how long should i have a reading?

            – just have to test the water daily?

            – if water evaporated ,can i just top up with “tap water”?

            thanks and more power

          • Hi,

            1. Yes, it’s normal
            2. Perhaps, in the next couple of days, it’s not an exact science, but nitrates should show up at the end of the second week.
            3. Yes, test it if you can.
            4. As long as it is dechlorinated!

            Hope this helps!

          • ok
            thanks again
            will update in a couple of days if no problem arises.

          • hi momchil.
            just an update and some follow up questions,,,

            – 4th day of cycling but still no reading yet all are still 0. is this normal?

            – you think i should wait a couple more days.?

            – after a couple of days if still no reading yet is there someting i could do? maybe dose again with quickstart?or can i put a drop of pure ammonia?

            – is there someting i have been doing wrong, follow step 1-5 to the point.

            – today is the 2nd time feeding my fish since the cycling start. when there is fish poop should i net it out immediately or just leave it?

            again thanks very much

          • Hi,

            Leave the poop to kickstart the cycle. Anyhow, it’s not an exact science, but what you’re seeing is totally normal.

            Also, don’t pour pure ammonia inside a tank with live fish ever!

          • hi momchil,
            i’m reviewing your replies to me and boom!

            just remember i ask you if water evaporated can i just top up the water..?
            didnt notice you mention “dechloronated”

            now i just remember i added water (1 pitcher) straight from tap, couldnt that be the part i have done wrong.?

            what should be my next step to solve this?


          • Yes, any water you put in your tank should be dechlorinated! Chlorine is harmful to both bacteria and fish.

            You may need to dechlorinate with something like Prime and start the whole process all over again. How are your fish acting?

          • hi momchil,

            fish is doing fine and healthy, vicious eater , never noticed but the barb seems to grow bigger.

            – start all over meaning dose with quickstart again?

            – can i double dose with fish in tank?

            -leave the water , no need to water change?

            luckily its just only 4days ,discovered the mistake i make.

          • by the way, i”m just using api stress coat to dechloronate the water.

            will that be okay?

          • Yes, that a great choice, in my opinion.

          • Hi

            IF you’re sure you used tap water then you may want to add a little API Quick Start, yes. No problem adding it while there are fish inside the aquarium. Also, you are correct in your assumption not to change the water for now. Leave it as is, add some more QS and wait it out.

            Good luck, Peter

            P.S. – Better late than too late 🙂

          • okay, will update in a few more days.

            thanks again

          • hi momchil,

            just test the water today.

            temperature – 83
            ph – 7.8
            ammonia – in between 0 and .25ppm
            nitrite – 0
            nitrate – in between 10 and 20ppm

            its so hard to check the colors of the chart, especially with ammonia and nitrate.

            – should i be waiting for a reading of nitrite?
            – m sure the tank isnt cycle yet? based from the readings above, its just my 8day all in all including the mistake i make
            – fish is healthy and eating viciously when i feed, do i still feed every other day?
            – how long should i leave the poop in there before i scoop it out?

            hope i’m in the correct path now.

            thank again

          • Hi, again friend,

            Your fish tank is likely cycled now, the nitrates showing up and the low levels of ammonia and nitrite indicate that. Well done!

            It’s totally possible that this happens on the 8th day, no need for concern.

            Feeding every other day is a good rule of thumb for overall tank maintenance. If you switch to everyday feeding be very diligent with doses. Don’t feed “as much as the fish could eat in 2 minutes” (which is how most commercial foods advertise it). Fish have small stomachs and don’t need a lot of food in general (per offering).

            You can scoop the poop once a week or more often if your nitrates shoot above 15-20 ppm.

            You’ve done an excellent job 🙂

            P.S. – when you’re about to add new fish – don’t add too many at once! This could throw off the nitrogen cycle off balance and cause ammonia and nitrite spikes.

            You’re now ready to start enjoying the hobby. Good luck, man!

          • Hi Momchil,

            really? never thought it would cycle that quick.
            i was still expecting to have nitrite reading.

            well as you said so , its cycled! but will wait for another week before getting fish.

            – should i do a water change 1st before introducing fish next week?

            all of this would not have happen if not for your method and detailed instructions . specially you answering my every inquries to the point.

            will still update here from time to time.

            i like to say Thank You very very much.

          • Haha, no problem, Peter, that’s what the blog is for!

            Wait another 2-3 days, and do a partial water change. From there on, do the usual weekly maintenance (water changes, vacuum poop out, etc) Don’t change too much water at once. No more than 20% per water change. If you need to change more than that, do it on intervals (say, 1 x 15%, and another 1 x 15% in 2-3 hours). This prevents stressful environmental changes for the fish.

          • Hi Momchil.

            sorry but i have few more questions…

            – if adding new fish should i still dose with quickstart?

            – what should be the maximum reading of nitrate in a 10gallon barebottom tank?

            – i have read somewhere that if you overstock your tank, it will result to nitrate spike. m planning of getting.. 1 – dwarf guorami
            4 – rasboras
            4. cory cats
            is that too much?

            thanks again

          • Here are some thoughts:

            1. By adding bottled bacteria upon the introduction of new fish you’re making sure the bacteria can handle the new bioload. However, that’s not needed in a mature tank, unless you are adding way too many or large fish at once. My opinion – it can only help to add some!

            2. I usually don’t recommend more than 10-15 ppm of Nitrate levels longterm. I have an article on that here in the blog, just type in “nitrate” in the search bar and click the one that explains high nitrate levels.

            3. That’s beside the tiger barbs? Tiger barbs will show aggression unless in groups of 5 or 6. I would not recommend 5-6 tiger barbs in a 10-gallon… I would return the barbs to the pet store. Dwarf Gourami is a good choice. You could pull that one off if you pick the rasboras to be Chili Rasboras (Boraras brigittae) and if the cory cats are dwarf cories (Corydoras hastatus). Google the scientific names to see the fish. I also have an article on small fish here in the blog. Type “smallest” in the search bar and you’ll see it.

            Also – if you have the opportunity – get some live plants. There are beginner aquarium plants that don’t require substrate such as the Anubias and Java Fern among others. You can use superglue (it’s safe no worries) to attach them to a piece of decor or, better yet, a piece of driftwood. You can also put in some floating aquarium plants in there. These will help tremendously for keeping Nitrates and other pollution in check, naturally (I also have an article on floating plants here if you need more info).

            Hope this helps! 🙂

          • Hi momchil

            thanks so much again..

  7. Unfortunately I put the water conditioner/dechlorinator in first then no more than an hour later put in the double dosage of API quick start. Should I start over?

    • Hi,

      Well, yes. What fish are you using to cycle?


  8. Hi thank you so much for the article! It’s helped me a lot in setting up my 10 gal Betta tank. I got my fish 10 days ago and started with Tetra SafeStart as you suggested–however, my tank has been at 0 ppm for ammonia, nitrites, and nitrates ever since then! My only guess is that since my tank is pretty heavily planted, the plants are filtering out ammonia faster than the nitrifying bacteria can. I started out feeding him every other day, but after about a week I began to feed him twice a day. I suppose this isn’t the worst problem to have, just a little puzzled as to what’s going on. Let me know if you have any advice/ideas for my next steps, thank you!

    • Hey, Patrick!

      You’re using a liquid test kit right? Shaking the vials well? If so, then I would assume that it’s your live plants’ doing (as you mentioned).

      I’d reduce the feeding to once a day, just in case (your Betta buddy won’t starve, no worries).

      Fish is acting normal, correct? If yes, there’s nothing to worry about.

      If I were you I would keep a dose of beneficial bacteria ready, but in the case of a heavily planted tank you may not need it.

      Keep monitoring the readings and as soon as you see any nitrAte and no ammonia, or nitrIte you can assume that the tank has been successfully cycled.

      Regards, Momchil

      • Thanks for getting back! Yep I’m using API master test kit. Fish is acting totally normal–thriving actually 🙂 I’ll reduce to feeding once a day and just be patient haha. Thank so much!

  9. API quick start

  10. Thanks you’re article cleared up my concern used quick start on small 70 let tank and it’s cloudy also used zone and stress is this ok for new tank

    • Hi,

      cloudy water is completely normal.

      When it’s during cycling, it will go away on its own.

      Just wait it out. 🙂

      Hope this helps.

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