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. Hello again,

    Thank you so much for your replies 🙏

    Since my last reply, instead of water change, i added more water, because it seems like the water is evaporating fast, the water i added was cured with anti chlorine and i let it sir for 48 hours.

    I had tested it yestersy, and my ammonia was down.

    It’s at 0.25 ppm, nitrite is spiking a bit at .50 – 1ppm
    Nitrate is still at 5ppm.

    What i don’t understand is some
    Of my plants is starting to sprout, it’s actually so cute and i was so excited haha.

    I’m on my 11th day now, and my 14th day will be up soon, but i’m still not near 0 0 0 readings.
    I use API freshwater liquid test kit.

    I also tested my tap water, and it has no ammonia.
    I’ll follow your advice and add more live plants.

    I’m not sure what i’m doing wrong but i only feed about 4-5 pellets ( i even cut it in half per pellet and make sure he eats them first one by one so it doesn’t go down, but i think my fish is struggling to fit it in mouth? When he loses it and the pellet goes down, he doesn’t follow it anymore haha.

    And i make aure to only feed him every other day.

    I’m thinking, maybe my light has issue?

    My aquarium is inside my room, no source of sun, i have no windows.

    But i have a big flourescent light in the middle, and i only open my aquarium light for about 3-4 hours a day because i’m thinking the light in the room might be affecting it too.

    I will start to stock water on my 12th day for change on 14th. And i will test it before doing so.

    Again thank you so much for replying!

  2. Hello, i’m sorry i am very new to the hobby ( i just started yesterday ) and would like to do it right the first time, so i’ve been researching and asking a lot of people but i’m confused as there are a lot of difference in opinion.

    I just decided to stick with your method instead.

    I planted my tank yesterday with stones. And had water change too, i added Aqua care for the chlorine. And today it’s 24 hours, i’m waiting for my api quickstart, it will be here in a few hours.

    My question now is, i only have a 14 gallon tank.
    As per my understanding, i will have to put double the recommended dose of my api, and then i’ll have to put 1 fish right away.

    And then not test it for 2 days and no lights for 2 days as well.

    I only have to feed the fish every other day, no water change for 14 days.

    Am i getting this right? I’m sorry i have to ask 🙁

    I’ve never taken care of a fish before.

    • Hi, Miya,

      Sorry for the late response – yes, that’s precisely what you should do if you were to follow my process.

      Did you start?

      • Yes! I started, this is my third day with no water change since the first day i double dose it with API. And added 1 fish ( added small endler guppy )

        I’ll be recieving my test kits tomorrow, so i’ll be able to check my water parameter.

        I’m so glad you replied! I’m starting to worry, the water is becoming a little cloudier than usual.

        I suspect it’s the food on the ground, but i don’t have a gravel vaccum 🙁 and everytime i try to get it they dissolve.

        Is it a good idea to get 1 panda cory for this foods? 😥
        But it’s been a day and a half, and the food is startinf to have some cotton on it.

        Thank you so much again for you reply.

      • Hello!
        I’m on my 3rd day now since i added a quickstart.

        And luckily, my test kits are here now. 🙂

        My test results are:
        Ammonia – 1ppm
        Nitrite – 0.25
        Nitrate – 5.0

        Should i be worried? I haven’t done anything yet, no water changes, only feeding the fish.

        But i admit there is some food left on the substrate, but i have no gravel cleaner, is it worth adding a small panda cory or pygmy cory below, will they eat the food on the substrate? 🙁 or shrimps?

        I also wanted to ask if it’s normal that i noticed that the water in my tank is evaporating day by day, i mean the level is getting low a bit day by day?

        Thank you again.

        • Hello,

          I would try to remove the food particles manually, if possible. They add to the bioload. Is there a lot of them? I’m sure a single Endler can’t be responsible for 1 ppm of Ammonia in a 14-gallon tank.

          Also, you can pour in some more beneficial bacteria if you have left.

          Adding a panda cory will just add to the bioload as it will create waste too.

          Anyway – on to your other questions – it’s ok if you see the water becoming cloudy. I have an article on that, but just to summarise – it’s normal during cycling.

          And as to water evaporation – that’s also normal. You can top the tank off with some water, but make sure the top-off water is near or the same temperature as the tank’s water. You don’t want to shock your guppy friend with cold water.

          Hope this helps.

          Keep me posted.


          • Hi again! 👋

            Today is my 6th day in cycling, yesterday my tank became so cloudy i can’t barely see anymore.
            When i checked my filter, my wool is so dirty, i got a few water from my aquarium and clean it with it, i didn’t add or change water, and now it’s crystal clear again.

            But i just did another water test,

            It seems i have nitrite spike 🙁
            Ammonia 1ppm ( it didn’t seem to go down 🙁 )
            Nitrite – 0.5- 1ppm
            Nitrate – 5ppm

            I’m thinking of adding some water, since the water has lessen a lot since the first day.

            I also seem to have staghorn algae infestation on my plants 🙁 and maybe that’s why my ammonia or nitrite is spiking 🙁

            And yes, i only have 1 guppy endler on my 14 gallon tank, and live plants. 🙁

          • Hi again, and sorry for the late response.

            Ok, so the filter pad cleaning may have not been a good idea. The debris in it can attribute to cycling and likely had some bacteria on them.

            May I ask what you’re using for water tests? A liquid test kit or the strips? Strips can be inaccurate.

            Is the Endler acting weird so far?

            Algae is more of a consequence of the high ammonia, rather than the reason. To control it and not let it take over you can add a little more live plants. They will use up the nutrients in the water and will outcompete the algae.

            Did you give my article about high Nitrite a read, by the way? Type “nitrite” in the search bar of the website. I would like you to pay close attention to the part where I list what could cause a Nitrite spike, as it’s the same with an Ammonia spike.

            …And judging by your readings, something is producing too much bioload in your tank. Are you sure you’re not overfeeding?


  3. Hi,
    Thanks for your awesome article! I love how clearly you share your knowledge and experience. It’s great for people like me, who want to know absolutely everything so normally articles raise more questions than they answer. Yours don’t give this issue!
    I’ve recently started up a new 160L tank to transfer my 2 small goldfish to. (background: got a fish before I had a tank, bought 25L tank. Added gravel, plants and air stone. Week later added a 2nd, smaller goldfish because he needed a friend… After the second fish, I started reading up more and more to make sure I was giving them the best care. Which I wasn’t. Made adjustments and bought a bunch of stuff, but with the small water volume I just couldn’t get the cycle sorted anymore. This got me to a week ago when my new tank arrived and I added black flourite sand, plants and fluval u4 filter.)
    In any case, I added 2 small nerites to the tank about 3-4 days ago to add some bioload and make sure algae doesn’t start. I added the recommended amount of API quick start on the second day of the filter running. And then some more a day or 2 after, and again some yesterday after a 10% water change and some plant maintance + adding tropica’s cheap co2 system (cannot afford proper co2 injection and most of my plants are easy care, along with my LED light being low light).
    That evening (last night), is when I read your article and clarified a lot of information. About the new tank, and also the small one they’re in now which I have been using Prime for during the daily water changes, and thus shooting myself in the foot.
    The only questions I have are as follows:
    When using API as per your article, do I dose daily, or just once? I won’t do any more water changes from now until the cycle is established.
    Will the nerites keep the bacteria going for another 2-3 weeks? I need my plants to root down well before the first goldfish gets moved over (I’m moving the smaller one over 7 days before the second so that the bacteria can adjust and also because she then has a chance to grow to a more similar size as the other fish. She is also the least destructive out of the two for my plants) because, with them being goldfish, they love to uproot and munch on my plants so they need time to grow and get established before that.

    I also have a larger nerite in the small tank because I get quite a lot of diatoms in that tank, and was considering moving him to the new tank as well. I am also considering getting some cheap cherry shrimp for the big tank because their bioload is negligible (from what I’ve read) and they can hide from the fish in the plants later down the line. It wouldn’t be the worst thing if that doesn’t work, because I can set up the smaller tank for the shrimp and as a plant grow tank once the fish are transferred and the tank cleaned. Would this be alright?

    For reference, my readings over the last 4 days are:
    (nitrate comes out of the tap at 5-10 when I tested untreated tap water. Also no ammonia in our tap water).
    pH 7.6 high pH 7.4 ammonia 0 nitrite 0 nitrate 5
    pH 7.6 high pH 7.4 ammonia 0 nitrite 0 nitrate 5
    pH 7.2 ammonia 0.25 nitrite 0 nitrate 5
    pH 7.2 ammonia 0.25 nitrite 0 nitrate 5

    Thanks again for your article, and any help you can offer! Sorry for the long post…

    • Hi there Laura,

      Thanks for the compliments and thanks for being a reader.

      Let me try and answer the “only” questions you have 🙂

      1. You dose it once in the beginning and save another double dose for emergencies, such as the ammonia rising after 7-8 days (which should not happen).

      2. Nerites will keep some of the bacteria. The bacteria’s natural response is to adjust their numbers to the amount of available food (ammonia). There will be an adjustment period after you add fish. Also, kudos for doing your research and deciding to add your goldfishes one by one.

      On a side note, I’m literally in the process of writing an article that discusses plants for goldfish… You could give it a read when it comes out these days. Anyway…

      3. I’d say move the larger Nerite to the new tank. Typically, diatoms kind of sort themselves out with time.

      4. Goldfish are primarily herbivorous but they still remain opportunistic omnivores (as you’re probably aware as an owner). They may or may not try to snack on the shrimp. If it’s not too much of a hassle you can drop a shrimp or 2 in the tank with the goldfish and see how that works out (after the tank has cycled). If your goldies decide they’re not interested in going on a rampage with the shrimp then you may even see the cherries breeding. There’s another scenario where the adult shrimp fend for themselves well, but the goldies eat their babies. My point is – it will be pretty much trial and error for you.

      Four days is still early but you have cool readings. They mean the nerites are producing enough waste to start the ammonia-oxidizing bacteria. Also, the drop in pH means there are SOME strains of bacteria at work.

      Anyway, I hope this helps.

      Shoot me up another comment if you have more questions or if you just want to keep me and other readers posted with your progress.


      • Hi, just an update on the 160L tank and some new questions.

        I did as you suggested, and moved the nerite the new tank as well on the day of your reply. I didn’t perform any water changes for 2 weeks and slowly the ammonia build up to 0.50 and 2 days later the nitrite reached 0.50 as well. After 2 more days it was above 1ppm, the day after which it was suddenly at 5ppm. About 3 days after that, my ammonia was back down to 0, but the nitrite was still at 5ppm (where the test stops so maybe worse, I don’t know. After 1ppm the colours get hard to separate).

        After 3 days of extremely high nitrite, I did a small water change (this was after 2 weeks of letting the tank cycle) of about 10% which seemed to bring it from 5 to 2ppm and nitrate from 20+ to 10-20.

        The day after, I did nothing. The following day the big nerite fell off the glass and had his trapdoor shut. He didn’t smell and I put him on the pebbles, right way up. That day I did a 18% water change and had the same levels as the previous day so nothing changed. I figured the water change was too small so I read that a 30% water change should bring the levels down. I planned to do that the next day (the 3rd of November).

        When I woke up, I saw one of the smaller nerites had also fallen off the glass and had his trapdoor shut. While I was opening the hood to take all the snails out and put them in a temporary home with clean water and prime, I saw him open his door a little and close it again. He’s been fine since being in the clean water. The big one is still totally shut and still, but still no smell of death. I did a big 56L (37%) water change about 4-5 hours before doing the water tests and added some Quick Start to top up bacteria.

        The test is still identical to yesterday. Ammonia 0, nitrite between 2.0 and 5.0 (I really can’t see the colour difference at the point it is) and nitrate now 10ish.

        Could you help me understand why the water changes aren’t reducing the nitrites? I’m worried that the high level will stall the cycle or kill the bacteria that are supposed to process it into nitrate.

        I’ve replaced the snails with some algae wafer in a glass for ammonia while they aren’t safe in the water. The glass is open, it’s just to stop the wafer disintegrating all over.

        I would really appreciate any advice and help because I don’t know what to do from here. My family isn’t super supportive of me doing big water changes very often so it’s all round not a pleasant experience and very stressful.
        Thanks in advance!

        • Hello again, Laura,

          “Could you help me understand why the water changes aren’t reducing the nitrites?” – To be honest, that’s a very good question. One I’m unsure how to answer though. I have a theory about what’s causing all of this, however. I carefully re-read your first post and noticed that you’re using CO2. (sorry I missed it the first time)

          Is the pH in the cycling tank dropping abnormally fast? CO2 can lower the pH, which in turn can stall the work of certain bacteria strains, true. Not many know this but one of the main reasons we change water is to prevent the constant decrease in pH that’s a result of bacteria at work. Since you’re cycling the tank and not changing its water it could be that the two effects stacked right before you started with the water changes. It’s possible the bacteria that convert Nitrite to Nitrate are among those strains that get stalled. This study suggests I may be right –

          So stop the CO2 system for now. It may be that it keeps the pH low enough to suppress the work of the bacteria, which could explain why the values don’t change when you exchange the water (assuming the snails kept producing bioload). I know this explanation does not hold up terribly well, but at this point, it won’t hurt to try anything.

          Another note – Tetra SafeStart Plus is better at handling Nitrite than API’s QuickStart. I usually recommend using QuickStart in well-planted tanks where the plants can suck up the excess Nitrite quickly. Such plants are usually the ones that grow faster than usual because they need more of the stuff. Are your plants slow growers? Java Fern is a relatively slow grower for example?

          Do you have the opportunity to get Tetra SafeStart? Also, it’s worth noting that if my CO2 assumption is correct it won’t matter if you’re using TSS or QS.

          Finally – sorry your family doesn’t support you through aquarium hardship… If that makes you feel better – my parents were the same at first… We aquarists are rarely understood.

          Anyway, let me know if things fall into place. Good luck

          • Thank you again for your advice.
            Yes I do use a bit of co2. It’s the tropica system 60 (Bell system) so it’s meant for 60L tanks. The pH did drop slightly after the tank started to cycle, but not very fast. As standard, it’s in that annoying zone of the API master test kit where it reads as 7.4 pH and 7.6 high pH…
            Then it went down to 7.2 and has mostly stayed at that level. I think it does match up with the co2 use, like you explained.

            I’m not sure what’s being produced in my tank now, as I took the snails out when the nitrites started to get too dangerous and I saw 2 struggling. I put some food in there to rot for ammonia (in a small glass so the mess doesn’t spread) and I have some plant die off, which will cause some ammonia but no idea how much… All my monte carlo failed, but I left it in the tank for the sake of ammonia now that the snails aren’t making any waste in there.

            My plants are mostly moderate and relatively fast growing ones. Elodea densa, myriophyllum guyana, rotala rotundifolia, ludwigia glandulosa, Bacopa Monnieri, compact and caroliniana (hope I remembered that right), hydrocotyle tripartita and some other small plants. I don’t know if they are fast growing enough to use much nitrite.
            I did buy some tetra safe start because I thought I would add it when it’s time to move the fish in (figured I’d use it with the second fish, because he is the largest and I’ll probably use up the remainder of the API bottle with the first fish).

            Thanks for your reassurance, it helps to know that it happens to other fishkeepers too! If only the rest of the world treated aquatic life as well as they did “standard” pets.

            I’ll hold off on the co2 for now until I see some changes. Thanks again for sharing your knowledge and experience!

          • Another update (in case it helps others with similar issues):

            The tank did eventually cycle. It took 33 days in total. I put the nerites (2 small ones, the larger one did not survive 😢) back in once the parameters were safe. Left the tank another 4 days and no differences in results showed up. So I moved in the first, smallest goldfish. Got her all acclimated and finally let her loose.

            I am SO glad I didn’t try to add both fish at once. The first day was fine. The second day I realised the fluval u4 was too powerful for the little fish to handle and she was being pulled by the flow when she tried to sleep or rest. I made a temporary solution out of a cleaned plastic bottle with some holes poked in and used that to cover the filter outflow.

            The next day I saw a little increase in nitrite. Not yet 0.25, but definitely more purple than 0. I was kind of worried that maybe plastic bottles release chemicals into the water or that the bottle was stopping too much water going into the filter and it wasn’t getting to the bacteria. So I removed it.

            Nitrites kept steadily rising (0 to 0+ to 0.25 to 0.25+ to 0.50 today) so I’m not sure what to think.

            Today I did a small water change. 32 litres comes out around roughly 20%. I then put the bottle back over the filter because my little fish looked stressed from the effort when she tried to rest. Topped up bacteria after a few hours. About 5 hours more and I did today’s tests.

            Ph has gone down again to 7.2 from the normal 7.4 I get. From earlier replies and articles by Momchil I know this is a sign bacteria are working. Great! I don’t want to stress the poor fish for any longer.
            Ammonia 0.25 (hadn’t budged from 0 for weeks)
            Nitrite 0.50 (up from 0.25+ last night regardless of the water change)
            Nitrate 20 (up from 10 the last 1.5 weeks).
            I took the bottle back out. I want to get some sort of hardscape to disperse some of the outflow long term, but I haven’t managed to get to the nearest shop that sells it (1.5 hours drive one way).

            Is this happening normal? It kind of feels like “what was the point of that 33 days of it needs to cycle again with the fish?”
            On top of that, I’m struggling with the filter flow issue, the filter was too expensive for me to replace plus I’d have to start all over again, so it’s not feasible in my situation; and I’m having some real issues with algae and diatoms not going away. My tank is covered with salvinia when the bottle covers the filter because nothing is really pushing it to one side and then algae and such starts to disappear. I have 2 lights because with 1, my carpet plant grows up instead of across. Now it grows beautifully across the substrate, still not perfectly down but it looks like a carpet. But without the bottle, the salvinia is only on one side and I get diatoms all over the other side. 4 of my plant species are taking off like mad, and I have to trim and replant some every 2-3 days which is awesome! So what is up with the algae and the parameters?

            Does this hobby make any sense at some point or become any less of a mystery as time goes on? Or feels like everything that can go wrong in my tanks, will. Sigh.
            Thanks for bearing with. I’ll update once things start to look up. I’m feeling hopeful about next week xD.

          • Hi again, Laura,

            Thank you for keeping me/us up to date. I have to say, yours is an exceptional case, especially the “33-day” part. It does not surprise me that snails did not make as much waste as a goldfish, but I honestly have no idea why it took your tank so long to cycle with just 3 snails…

            I think we’ve all had this one tank where nothing worked as it should and things made no sense whatsoever. Unfortunately, it seems for you – it’s your first one. 😀

            As for the hobby… it does get better. It’s just that it’s a combination of chemistry, biology, and physics and many underestimate that fact.

  4. Hi im back. Hope you have been well
    To everyone still reading this….It works! ive used this method to set up a 55litre and a 125 litre with no issue. Im only back to check what the dosage would be for my 315L.
    would it still be a full bottle only or maybe 1.5?

    im also gonna be using an fx4 external filter. hopefully all is still as written.

    • Hi KA,

      Thanks so much for getting back to us – I’m sure my readers will be happy to read your feedback.

      I’d use a bottle and a half. 315 L is around 80 gallons, and the bottle says it treats up to 100 gallons, so I’d be on the safe side if I wanted a fully cycled tank in 2 weeks.

      Anyhow, the FX4 is perfect for an 80-gallon tank, it will let you stock a lot of messy fish if you want.

      Good luck, KA


  5. I have 9 small Coldwater fish in my 40 gallon tank i did not start the cycle. Should i wait till the ammonia from the fish waste and food is at a certain ppm before adding the tetra safestart plus so the bacteria has food to eat? Or should i just keep putting a bottle a week in the tank with the fish?

    • Hi,

      Despite there being no ammonia yet, you should NOT wait because the fish WILL produce waste and it’s just a matter of time before the levels rise.

      In fact, it should be your top priority not to let the ammonia spike.

      Following these thoughts, add the bottle as soon as possible – the bacteria will adjust their numbers according to the available ammonia.


  6. We are seeing between .25 and .5 ammonia today, day 8 of new 5 gallon tank with Betta in. Wanting to lower it of course…we’ve been adding double dose of api quick start since day 1, do we keep adding the bacteria every day until day 14? I have 2 gallons of tap water with dechlorinator added this morning ready to use tomorrow morning to lower ammonia. What else do we need to do?
    Also, today our 2 betta bulbs looked awful so I trimmed the brown leaves down to the base and added half a flourish tab to the base of each one in the gravel.
    This is an 8 day old tank so I know we have to keep an eye on it. So far fish is showing no signs of stress, ph is 6.8-7.3 depending on brand of strip we use. Lol

  7. Hi, I followed your instructions to cycle my 10 gallon tank using tetra safestart plus, used the bigger bottle, I’m on day 14 and have been testing the water daily with the api master kit for PH, nitrite, Nitrate and Ammonia every other Levels were all 0ppm by day 11, with the exception of nitrates which were showing 5ppm. Day 12 my Ammonia went up to .25ppm and today (day 14) Ammonia is closer In color to .5ppm, nitrite 0ppm, ph 7.2, and Nitrate between 5ppm and 10ppm. Is this Ammonia spike normal?

    Was planning on vacuuming the gravel as I can see bits of old food stuck in there and then add some new water(already have some conditioned and will be ready tomorrow)also would add a small bottle of TSSplus.

    What are your opinions and suggestions?
    Thanks in advance!

    • Hi Jordan,

      Yes, what you’re describing is unusual. Your tank was cycled before that so there’s something contaminating it. I was about to guess that there may have been some leftover food on the bottom of your tank but you said it yourself. I would recommend just vacuuming the substrate and feeding less (as apparently, some food gets to the bottom). The water change should help with negating the ammonia spike.

      Good luck!

  8. I used the terta safe start yesterday with a fish in the tank (im new) and my nitrites are threw the roof with no nitrates did I get a bad bottle?

  9. Hi! I started a fishless cycle but with plants. After reading your article I’m deciding to go with api QuickStart. However I have questions. Do I need use ammonium chloride first? And then add the QuickStart? Or what process do I take?

    Thanks! Will be adding pea puffers once my tank is cycled!

  10. How do you do this without a live fish

    • Hi,

      By adding fish food to the aquarium. It will start to decompose and ammonia will rise, kickstarting the Nitrogen cycle.


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