How to Get Rid of the Foggy Water in a Cloudy Fish Tank?


Seemingly insignificant changes in the water of an aquarium may sometimes throw the whole system off balance.

In one of these instances, the water in the fish tank may become so foggy that you can no longer see through it.

The foggy appearance may be caused by a bacterial bloom in the water column, which is typical for new fish tanks.

The cloudy white water may form just one day after setting up the new aquarium, but it can last for 2 to 4 weeks.

Though a large water change seems like an intuitive solution, it can actually worsen the cloudiness.

To clear up the foggy water in your fish tank you should first identify the underlying cause.

Why Has the Water in Your Fish Tank Become Foggy?

The initial causes of foggy fish tank water vary, however, the mechanism that is triggered is almost always the same.

In 9 out of 10 cases, bacterial blooms may be at fault:

The water in a fish tank may become foggy due to an overabundance of organic nutrients in the system. Specific bacteria consume the nutrients and bloom in the process. These bacteria have the ability to double their populations in 15 minutes, which eventually causes the water to become cloudy white from their sheer numbers.

New aquarium that has cloudy water

By NeonAlpaca

It’s most common to witness a bacterial bloom in the water of a brand new fish tank. In this case, bacterial colonies are still establishing their hierarchy, and the foggy water usually forms a day or two after setting up the aquarium.

Some less common reasons for foggy aquarium water are the presence of microbubbles, a chemical precipitate, and dust from an unwashed substrate.

Take note that if there is a green tint to your aquarium and it looks somewhat cloudy, it will not be addressed by any of the above.
An aquarium that has a cloudy green water.

By jasper502

This cloudy green water is likely caused by a microalgae bloom.

That being said, let’s take a detailed look at each of the causes.

  • Excessive amount of organic nutrients – Healthy aquarium water will have all kinds of bacterial colonies to support it and feed off its nutrient content.

    The water of a new aquarium may become foggy because some of the new bacterial colonies are blooming faster than others.
    How a bacterial bloom makes the water in a fish tank foggy.

    By zConcept

    Aquatic bacteria are divided into 2 general types:

    • heterotrophic bacteria
    • autotrophic bacteria

    The former prefer to consume organic matter to survive, while the latter can synthesize their own food from inorganic compounds.

    In an aquarium, heterotrophs will decompose the organics in the water.

    The decomposing process is called remineralization.

    Carbon dioxide (CO2), Ammonia (NH3), Phosphate, and Nitrates (NO3-) are released through the remineralization process.

    The Ammonia will be then picked up by the autotrophs which will convert it to Nitrites (NO2-) and Nitrates in a process called nitrification.
    How the Nitrogen cycle works in a fish tank
    Autotrophs are the beneficial biofilter in an aquarium and they are the ones protecting the aquatic animals from Ammonia or Nitrite poisoning.

    That being said, the ones responsible for the aquarium’s foggy water are the heterotrophs.

    Heterotrophic bacteria can reproduce at a relatively fast pace of 15 to 60 minutes while the autotrophs take between 16 and 24 hours to double in numbers.

    This means that heterotrophic bacteria are realistically able to completely overpopulate the aquarium’s water column overnight.

    Following these thoughts whenever there’s an excess of organics in the aquarium’s water the heterotrophs will aggressively multiply to decompose them.

    This happens so fast they are unable to attach themselves on surfaces and instead saturate the water column, causing it to appear cloudy to the naked eye.

    Here are the common sources of organic nutrients in a home aquarium:

    • Each time you feed the tank’s inhabitants, the food that doesn’t get eaten sinks down to the bottom of the tank where it starts to degrade.
    • Each time an aquatic inhabitant produces waste, it remains inside the ecosystem, and starts to decompose.
    • Dead and rotting flesh of both aquatic plants and dead fish.
    • Another source of organic matter is the tap water used to perform water changes in most new freshwater aquariums. This is the reason why in some new aquariums the water is clouding up and becoming visibly foggy, even if there are no fish present.
  • Microbubbles from filtering gear – Occasionally, maintenance equipment for water filtration such as HOB filters or protein skimmers can produce millions of microscopic air bubbles in the water, therefore making it cloudy.
    Hazy aquarium water thanks to microscopic air bubbles.

    By corn_n_potatoes

    More often than not, it’s the power filter that produces the microbubbles in freshwater aquarium systems.

    If you doubt that your HOB filter may be the reason behind the foggy water in the tank, it’s worth turning it and waiting for an hour or so.

    If it was the culprit you’ll notice an improvement of water clarity in that period.

    The faulty build of the filter does not necessarily mean that it will not perform its water filtering duties correctly.

    It’s worth noting that, rarely, microbubble clouds in the water could also appear with a canister filter if its tubing is not properly connected.

    But could this cause water fogginess in a saltwater aquarium where HOB and canister filters are not commonly used?

    In a saltwater aquarium the usual suspect behind foggy water, that’s full of microbubbles, would be the protein skimmer.

    A protein skimmer does that as part of its job – it produces microbubbles on purpose.

    However, sometimes the build of the unit may not be flawless. This could cause a leak of microbubbles right back in the fish tank, which could make the water look very cloudy.

    How dangerous microbubbles are to the water’s inhabitants depends on the severity of the issue.

    The bubbles need to be addressed as soon as possible if they’re severe enough to cause cloudiness because large amounts of them can suffocate an aquarium fish by clogging up its gills.

  • Calcium Carbonate as a result of insufficient magnesium – Every time a reef keeper mixes beneficial salts with Reverse Osmosis water they should make sure that there’s enough Magnesium in the mix beforehand.

    Otherwise, Calcium Carbonate (CaCO3) could precipitate, forming small white particles that will eventually cover the aquarium’s interior and give its water a foggy appearance.

    The Magnesium should not only be put in the water first but it should also completely dissolve before the rest of the salt mix is added.
  • Fine particles and dust – The fine particles from a substrate that hasn’t been thoroughly rinsed before being put in the aquarium can make the water extremely foggy.

    Sand substrate making the water in a saltwater tank very foggy.

    By lapin

    Most aquarium substrates will be dirty out of the bag.

    I recommend thoroughly rinsing your new substrate or you risk fighting with foggy aquarium water for weeks.

Best Ways to Get Rid of Foggy Water in a Fish Tank

A fish tank that has developed foggy water.

By Dylan King

If the foggy white water seems to have developed suddenly, then it is likely due to an imbalance in the fish tank’s Nitrogen cycle.

The solution to this will change depending on the trigger, but I will outline some standard tools and techniques that will work once the problem is identified.

You can get rid of foggy water in a fish tank with the following ways:

Feed your fish mindfully, and keep the aquarium’s substrate clean to eliminate the excess nutrients that may cause a bacterial bloom. Also, improving the mechanical and biological filtration of the water may be one of the most reliable ways to quickly clear up its cloudiness.

1. Set up a UV water sterilizer.

Here on this photo you can see the dramatic improvement in water clarity, by using a UV sterilizer for 1 week:
A progression that shows how a UV sterilizer can clear up a bacterial bloom in the aquarium.

By awmbonke

The way a UltraViolet sterilizer works is by circulating the bacteria-infested aquarium water through a narrow tube with a UV lamp inside.

The lamp irradiates UV light, bombarding the bacteria’s DNA with high-energy particles, and causes them to mutate.

Said mutations prevent the bacteria from multiplying further, and quickly restore the balance in the water column, clearing the fogginess out.

I’d only recommend getting a UV aquarium sterilizer when you’d like to treat a case of cloudy water that has been going on for weeks or months.

If the water in your aquarium keeps getting foggy for this long, then, perhaps, an outside intervention to forcefully restore the bacterial balance is needed.

A UV water sterilizer clears up the foggy water in a saltwater fish tank.

By Zeo_Adapt

Another situation that justifies getting a UV water filter is when your freshwater tropical aquarium, or reef tank, is so cloudy that you can barely see through it.

I’m talking about a dense, milky white appearance.

Ultraviolet water sterilizers come at a slightly greater price than the other solutions listed here, however, they are the quickest and most efficient method of removing unwanted bacteria from the aquarium.

A UV light sterilizer will get rid of the foggy aquarium water in a matter of days (and sometimes hours), whereas other methods take weeks or even months to start showing results.

For most hobbyists, the overall cost of a single UV water filter is worth the long-term benefits it provides for their aquariums.

By getting one you’ll have immediate control over future bacteria blooms, and outbreaks of free-floating algae spores (causing the aquarium water to become cloudy green).

Another snapshot showing how effective UV water filters can be against cloudy aquarium water:
Before and after using an UltraViolet water sterilizer to clear up cloudy water in a fish tank.

By fishyfolk

Anyway, you can also periodically run a UV sterilizer in your aquarium as a successful preventive measure against different nasty parasites, such as both the freshwater and marine versions of Ich.

These water sterilizers are also commonly used in many hobbyists’ quarantine tanks, meant for monitoring new fish coming from the store.

To quickly fix the issue with foggy water, however, you’ll need to know the Wattage of the UV lamp that would best suit your aquarium’s volume.

A quick recommendation from Aquanswers: A UV sterilizer with a 9 Watt bulb such as the AA Green Killing Machine will work wonderfully in any fish tank that holds between 20 and 55 gallons of water. You can find this 9-Watt UV sterilizer at Chewy.com or Amazon.com, just to name a few vendors. For fish tanks of 20 gallons or under, I recommend the 3 Watt version, which can also be found at both stores. Click here to check it out on Chewy, or here to see it on Amazon.

If you’d like to go more in-depth I recommend checking out the Aquanswers guide on UV sterilizers.

Visit the link to check which product has the right UV lamp and GPH rating to clear the foggy water in your aquarium the quickest.

2. Vacuum 35% of the substrate every 3 days until it’s fully clean.

Foggy water forming in an established planted fish tank.

By PandabearXp

This course of action only applies as a solution to established aquariums that have long gone through the cycling process but are still struggling with foggy water.

Why would you clean 1/3 of the substrate but not the whole thing though?

To answer this question I first need to point out why you should be vacuuming the substrate.

Excess organic nutrients usually are the result of degrading fish poop or uneaten food that got stuck in the substrate.

So to get rid of the bacterial bloom and clear up the foggy water you need to remove the food source these bacteria are consuming in order to multiply.

In my experience the easiest way to do this is with a gravel vacuum such as this one, or any other similar device you can find in pet stores.

As we mentioned above, however, the beneficial bacteria (the ones you actually want to have in abundance in your aquarium) also live primarily on surfaces.

If you clean the whole substrate at once you risk removing the good nitrifying bacteria.

This could completely stall the Nitrogen cycle and you’ll end up back at point zero with, again, a foggy aquarium.

Therefore I recommend that you vacuum 35% of the substrate and wait for 3 days in between cleaning sessions to give the good bacteria a chance to restore their lost colonies.

After the third day, vacuum another 35%, and keep this sequence until you have the whole substrate cleaned.

I know that it sounds slow and tedious, but this is a safe and efficient way to restore the aquarium’s bacterial balance and clear up its cloudy water eventually.

Note that after you’re done it could still take another week or two for the ecosystem to fully stabilize.

3. Feed your fish every other day.

a murky aquarium
As the previous method, this one also applies to people who have foggy white water in their already-cycled aquarium.

It’s often that inexperienced pet parents feed their fish with more food than needed.

I used to be the same and justified doing so with fear of my little pets going too hungry.

Long story short, fish are relatively hardy and a healthy specimen can skip eating a meal for at least a week, without adverse effects.

This is because in the wild you can’t expect to eat a juicy amount of bloodworm or algae wafers on a daily basis.

For this reason, it’s likely better to feed less than your Betta fish or Goldfish can force itself to eat.

This way you’ll limit the food sources of the bacteria and the foggy water will begin clearing up in the next couple of days.

Otherwise, the food leftovers will sink to the bottom of the tank where they start to degrade.

This in turn may potentially lead to Ammonia spikes in the water, which are deadly to aquatic inhabitants.

A bacterial bloom caused by overfeeding can arise between 1 and 2 days after the leftovers were left to sit in the aquarium’s substrate.

The water in the tank will turn white and foggy when the bacteria are at their peak numbers, which usually happens at the end of the first day.

Note that, this method is best combined with the one above.

4. Perform smaller water changes with Reverse Osmosis Water.

A new fish tank that has foggy water thanks to an on-going bacterial bloom

By dawgs311

This section applies to people who are trying to treat a freshwater aquarium that continuously gets murky water.

I’m saying freshwater because almost all saltwater aquarium keepers already use RO water in their tanks.

Anyway, part of the problem here is that water changes larger than 10 to 15% can disrupt the biological balance in the water column, and give advantages to some bacteria over others.

That being said, if your fish tank keeps getting foggy and hazy, you should likely use RO/DI (Reverse Osmosis/Deionized) water for all of its partial water changes from now on.

That’s because, more often than not, tap water contains high levels of organic compounds.

When you perform a water change with tap water the non-beneficial bacteria get to work immediately and they start consuming nutrients directly from the water column.

This, in turn, causes the aquarium to become cloudy because the colonies quadruple their numbers in minutes and become visible to the naked eye.

The advantage of RO water is that it doesn’t have unnecessary excess nutrients.

When water goes through RO filtration it gets stripped from basically everything and what is left is mostly H2O molecules.

This process, however, removes the beneficial minerals from it as well, and most aquatic inhabitants get their minerals through water (unlike us humans).

You need to add minerals back to the water in order to make it fish-friendly again.

There are two products for aquarium water remineralization that I have been really happy with.

One is called Equilibrium and the other is Replenish.

You can easily find both products in your local fish store or online.

Replenish is targeted towards bare-bottom tanks filled with community fish, whereas Equilibrium works better for remineralizing water in planted aquariums.

Anyway, I do have some experience with RO water filters and one of the cheaper ones I ended up buying was this budget-friendly unit (link to see it on Chewy.com, but Amazon also has it).

I’m fairly pleased with it.

I also have a complete guide on RO systems, and though it’s suited towards reef tanks, the listed RO/DI units will work just as well for a freshwater aquarium.

It’s worth noting that fish stores may also sell RO water for about 50 cents per gallon.

Though this seems fine, let’s assume for a moment that you have a 55-gallon tank and you change roughly 20% of its water each week.

In this example, you can do the math and you’ll see that in approximately 3 months the RO water filter will pay for itself.

This means that In the long run, there’s a financial benefit from getting your own RO filter, aside from never having foggy water in your fish tank again.

5. Change your aquarium salt mix.

A reef aquarium with foggy water.

By MillsReef

This method is targeted towards saltwater tank keepers so if you’re not one of them, go over to section number 7.

Anyway, sometimes we want to diversify and try out new options when remineralizing our reef tank’s water.

There are two types of aquarium salt mixes that can fog up the water in a saltwater tank.

The first one is probiotic salts, which contain live bacteria.

These, when used in small water changes of under 10%, are okay and won’t cause clouding.

However, when used for a larger water change, there’s a significant chance of the probiotic salt causing a bacterial blossom.

The other type of aquarium salt mix that can make your reef tank’s water foggy is the one that simply needs more time to dissipate.

These will likely have it mentioned on the instructions label if it’s normal for the water to become a hazy white color during mixing.

6. Sprinkle Epsom salt before adding a salt mix.

A saltwater reef aquarium with crystal clear water.

By Learjet45dream

This method is again for people with saltwater aquariums and reef tanks.

Did your aquarium’s water become a foggy white color right after you added the salt mix to the RO/DI water?

And the white coloration actually comes from particles that look like tiny snowflakes?

That’s most likely a form of Calcium Carbonate precipitation.

I did some tedious research and it turns out that this effect occurs because of some rather complex chemical reactions.

To simplify it: whenever you’re mixing water for your saltwater tank, you’d want the RO/DI water to have enough Magnesium before adding the salt mix.

If the salt mix settles or dissolves before the Magnesium you end up with a huge build-up of Calcium Carbonate and some foggy water.

To prevent all of this you should just add some form of Magnesium to the RO water before you add the salt mix.

The cheapest way I’ve found to add Magnesium in the mix is with Epsom salt.

Epsom salt is Magnesium Sulfate (MgSO4) in its nature.

My experience with it has been that it’s a rather slow dissolver and it needs a bit of stirring.

There’s another Magnesium alternative that dissolves in seconds but it is also a bit pricier than Epsom salt.

That would be Magnesium Chloride (MgCl2), which is not easily findable over the counter, so here’s a link to it on Amazon.

It’s worth noting that sometimes the intrinsically interlinked pH, kH, and Calcium content in a typical saltwater aquarium can be in a “supersaturated state” which again would produce precipitation and make the water foggy.

To look behind the equations, I suggest that you read this article.

Anyway, this very simple trick effectively prevents the Calcium Carbonate precipitate and your saltwater aquarium won’t experience nasty water cloudiness.

7. Filter the water through Polyester filter floss media.

A freshwater fish tank with crystal water clarity.

By coconutofcuriosity

Filter floss on its own is an excellent tool to expedite the process of clearing up the foggy water in your fish tank. It is best combined with other methods and it works in both saltwater and freshwater systems.

It clears up any excess detritus very well as long as it’s changed regularly.

In fact, Polyester fiberfill is one of the best filter media for mechanical water filtration in an aquarium system overall.

In the case of microbubbles or a cloud caused by a sandy substrate, a good portion of filter floss media may solve the problem entirely.

The mechanical filtration provided by the microfibers is enough of a wall to partially filter out bacteria if that’s causing the water’s fogginess.

Filter floss is definitely a good addition to any tank and should be a mainstay to secure water clarity even after the cloudiness has disappeared.

Note that this will not solve the underlying problems behind the cloudy water, but it will act as a relatively quick and efficient way to make it crystal clear.

Just be sure to change the floss pads every couple of days.

8. Use a different aquarium substrate.

A brand new planted fish tank that's developing cloudy water.

By ThisIsBuzzard

Certain types of substrates can end up dissolved within the aquarium’s water, creating a murky or cloudy environment.

Aqua Soils used in freshwater planted tanks, for example, deplete with time, because they’re designed to provide live plants with vital nutrients for maximizing growth potential.

However, these substrates are often messy and can turn your water into a “dirted” version of itself.

Some hobbyists do this on purpose in order to simulate the brown, cloudy waters of the natural biotope of their pet fish.

However, most people that are new to fishkeeping should likely go with an inert substrate that has a beautiful appearance to it.

The inert substrates often do the work for aesthetics, but some of them, if not thoroughly washed beforehand, can contribute to a foggy aquarium with their fine particles.

This is normal to a certain extent and the water usually clears up on its own after the particles settle.

However, if a substrate that’s too light is chosen it can take a bit too long for it to settle in a medium such as water.

In my personal experience using Black Diamond Blasting Sand works best as a decorative substrate.

It settles easily and it’s also heavy enough to not get stirred by enthusiastic fish movement.

On the other hand, it’s not that heavy to compact and crush a sensitive plant’s roots.

If you’d like to keep live aquatic plants in a nutrient-rich Aqua Soil, however, you should know what to pick from and how to avoid messing up the color of the water.

I’ve compiled a guide on planted tank substrates and aqua soils for you to check out.

9. Wait it out.

A fish tank that is no longer transparent because of hazy green water.

By filipinofirebomb

The Nitrogen cycle in new fish tanks has a break-in period during which bacterial imbalances can cause cloudiness issues in the water.

If not aided by external factors, such as the addition of bottled beneficial bacteria starters, said period could last for weeks.

This is a natural part of the on-going establishment of an internal aquatic ecosystem.

If your foggy aquarium is new and it has just been set up, then your most reliable course of action is to wait for the system to completely establish its Nitrogenous cycle.

Foggy water, in this case, is a natural occurrence that may or may not happen, and getting rid of it requires no action on your part.

Usually, by the end of the “cycling” process, the cloudy water will clear up on its own.

Use liquid test kit and measure the water’s parameters once every 1 or 2 days to check if the tank is still cycling.

Liquid water test kits are generally better at telling you the real numbers than test strips, which is why I recommend them.

A solid proof of a foggy aquarium that’s still cycling are readings that show (in parts per million):

  • More than 0 ppm of Ammonia
  • More than 0 ppm of Nitrites
  • 0 ppm of NitrAtes

Even if only one of the aforementioned is true it’s to be considered as a signal for the ongoing establishment of bacterial colonies.

You should likely avoid disturbing the establishment of bacterial colonies during this time which is why it’s generally not recommended to change out the water of a cycling aquarium.

Why the Aquarium May Get Cloudy AFTER You Perform a Water Change

A bacterial bloom causing the water of a shrimp aquarium to go foggy.

By DoobDab

Dechlorinated tap water used for water changes becomes bacteria-friendly. Tap water also has organic compounds in it, which are the main nutritional source for heterotrophic bacteria in an aquarium. When you change a portion of the aquarium’s water with the new batch of dechlorinated tap water, heterotrophic bacteria start feeding directly from the water column. They multiply so fast and in such vast numbers that they overpopulate the water, causing it to appear cloudy.

Therefore, if you’d like to prevent your fish tank from getting foggy after each water change you should likely interchange the water source you’re using.

A good substitute for nutrient-rich tap water would be water that has gone through Reverse Osmosis.

The process of Reverse Osmosis removes the organic compounds from the water, which are responsible for bacterial blooms.

There are even studies suggesting that a portion of heterotrophs manage to survive in chlorinated water.

This means that you may be actually inviting more of these bacteria in your foggy aquarium during a water change with tap water.

A Bacterial Bloom in the Aquarium Water May Cause Fish Deaths

A goldfish fish tank with foggy white water.

By barracuda6996

When Heterotrophic bacteria bloom enough to make a fish tank foggy they convert higher amounts of organic matter than usual. Consequently, this process may cause a spike in ammonia levels in the aquarium’s water while quickly increasing its acidity. Both of these conditions are known to be lethal to aquarium fish and other aquatic animals.

During a bacterial bloom, the Heterotrophic bacteria also take up a lot of oxygen from the water.

As you can see there are more than one reasons for aquarium fish to be dying when the tank’s water becomes cloudy:

  • High Ammonia levels – Often, when a bacterial bloom is combined with fish randomly dying then it’s very likely that the cause of the mortalities is rotting organic matter in the water.

    The cloudy water could mean a dead fish has gone unnoticed, or leftover food has been stuck in the substrate.

    Dying leaves of aquatic plant matter can also cause the water to become visibly foggy.

    If you find that the ammonia levels are dangerously high (anything above 0.25) it could be a clever move to add bottled beneficial bacteria to the water.

    This will kickstart the establishment of the colonies required to oxidize the Ammonia into the much less harmful Nitrates.

    It’s worth mentioning that sometimes the Ammonia readings of the aquarium may remain at 0 while its water is still cloudy.

    This may be because there are enough live aquatic plants in the tank to take advantage of the excess inorganics (the Ammonia).

    Aquatic plants prefer Ammonia as their primary source of Nitrogen for growth and will take that over Nitrates when it is readily available.

    If a foggy aquarium is not planted, but the ammonia readings still remain at 0 PPM, the bloom was most likely caused by the organics introduced to the system via a water change.

    In that case, the release of Ammonia is negligible.

  • Increased water acidity – One of the reasons for performing on-going water changes in our aquariums, aside from removing a bunch of Nitrates is to also keep the acidity of the water in check.

    Bacterial activity in the water will steadily lower its pH value with time.

    Most fish can endure a steady change in water acidity.

    However, during a bacterial blossom that’s severe enough to make the aquarium foggy, the acidity of the water may begin to increase too quickly.

    What’s important to remember here is that water acidity changes on a logarithmic scale.

    This means that 6 pH is 10 times more acidic than 7 pH, but 100 times more acidic than 8 pH.

    Sudden pH drops, such as the ones caused by bacterial blooms can be lethal to both freshwater and saltwater aquarium fish.

    The more fragile aquatic inhabitants in the tank may perish during a foggy water event because the pH swing could prove too severe for them to handle.

  • Oxygen deprivation – During their process of decomposing organics, the Heterotrophic bacteria use up the oxygen in an aquarium.

    Usually, the used amounts are negligible in established aquariums with a stable Nitrogen cycle going on.

    However, during a foggy bloom, the competition for oxygen between bacteria and fish becomes vicious.

    The denser the milky look of the water is – the more severe the problem becomes.

    You may witness your pet fish gasping for air at the top of the water’s surface.

    This is one of those cases where installing a UV sterilizer would be adequate.

    The device will eradicate most of the bacteria in a couple of hours, whereas waiting for the bloom to sort itself out could sometimes take weeks.

    Don’t forget that in the meantime you can increase the foggy water’s surface agitation to allow for quicker and more effective oxygenation.

    The risk of suffocating fish during a bacterial bloom in smaller aquariums or fish bowls is much higher because of the small water volume.

Preventive Measures Against Foggy Water

Though certain natural processes in aquatic systems are inevitable, the damaging causes of foggy water are entirely avoidable.

I strongly recommend that you follow this checklist once you get rid of the bacterial bloom.

Take a look at these tested ways to prevent fish tank water from becoming foggy:

  1. Feed less than what you think the fish can eat.

    From my observation, I’ve come to the conclusion that overfeeding is, perhaps, the number one reason behind any imbalance of nutrients in these closed ecosystems.

    To keep the water’s organic matter in check you should feed less than what you think your fish could eat.

    Be precise and try not to go over a set small portion of food or you risk making the water continuously foggy.

    If the meal sinks down to the bottom and your aquatic pets did not see it – don’t sprinkle another pinch.

    If you do not trust yourself with precise dosing, you can get one of those cheap automatic fish feeders.

    They will feed a pre-set portion of food on a set schedule, controlling the number of food leftovers and keeping the cloudy water at bay.

    Another advantage of having one is being able to go out of town without the need of asking other people to feed your fish, who may or may not overfeed as well.

    I recommend Eheim’s fish feeder because it has done well by me and it’s also really durable.

  2. Clean parts of the substrate on a regular basis.

    The aquarium’s substrate keeps most of the organic waste that could potentially bring out a foggy appearance in the water column.

    The solution here is to vacuum the substrate regularly, but don’t forget to only do a third of the whole thing at a time.

    More thorough clean-ups may disturb the biofilter of beneficial bacteria that inhabit the bottom.

    For this reason, you need to clean portions of it to give the colonies time to regain their numbers in case of losses.

    Another reason to regularly clean the substrate is that a dead fish may remain unnoticed. This is a sure way to shoot the bacterial and Ammonia levels up, causing water fogginess as a byproduct in the process.

  3. Change smaller portions of aquarium water.

    Reducing the portion of the water you change will reduce the chances of your freshwater fish tank ending up cloudy.

    The more dechlorinated nutrient-rich tap water you pour down your aquarium, the more explosively the heterotrophic bacteria will multiply, making all the water foggy again.

    With a water change of no more than 10 to 15%, this will not happen.

    At these ratios, the new water will not be enough to cause a dramatic difference in the available organic nutrients in a short period of time.

  4. Replace tap water with RO / DI water for water changes.

    RO/ DI water is purified from the excess nutrients that may cause both bacterial and algae blooms.

    Even after dechlorination, the Heterotrophic bacteria will have no business in it, because it will lack food sources for them.

  5. Trim overgrown or rotting plant matter.

    The yellowing or wilting aquatic plant matter is to be immediately trimmed when noticed.

    Doing so is a reliable way to bring the white foggy water in your planted tank back to stability.

  6. Add fewer new fish at a time.

    Gradually overstocking a tank should not cause its water to become foggy as long as you patiently add up small fish in small numbers.

    However, if you add more than 3 medium-sized fish, relatively to your tank’s size, you are likely asking for a bacterial bloom to occur.

    If you happen to own a 5-gallon aquarium, you can click here to check what fish and invertebrates would besst fit in, without overwhelming the system.

  7. Filter the water through UV light regularly.

    UV Lights work by impeding the excessive presence of bacteria in the water column.

    Not only does it work for clearing up the foggy appearance of the water but it also is an excellent preventative measure against it.

    UV light can be extremely effective to control Heterotrophs (the Ammonia producers).

    Regular treatments with a UV sterilizer are a very helpful tool in making sure bacterial colonies are kept at a manageable level.

    Getting an Ultraviolet sterilizer will also help you maintain a parasite-free water column. This is a huge advantage in my book, having treated a couple of devastating Ich outbreaks.

Striving for a crystal clear fish tank water

Foggy water in the aquarium is easy to get rid of once you understand what you’re battling.

Your fish tank is host to much more than just fish, and runaway issues such as Heterotrophic bacterial blooms can indeed occur.

Assess the amount you feed to your aquatic pets, as excess food and waste are great for Ammonia-producing bacteria and bad for everything else.

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