How To Get Aquarium Water Crystal Clear?

When you acquire an aquarium or plan to keep a fish tank at your home, you have the vision of a clean aquarium with colorful fish swimming freely in the tank. No one wants a fish tank that doesn’t give a visible sight of fish. I know how stressful it gets when you see the water in your fish tank cloudy and foamy. But why does your aquarium water is getting cloudy? How to get the aquarium water crystal clear?

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When you know the root cause of the problem it is easier to solve it. Using Filter to using activated carbon, getting a crystal clear aquarium water can be your cup of tea if you know what you are doing.

But if you ask me, prevention is better than cure. Don’t let the aquarium water get cloudy in the first place except for the first days after you add a fish.

I know this is just a layer of information so I am here to elaborate more for you. In this article, I will be talking more about why aquarium water gets cloudy and what can you do to make it crystal clear all the time.

Let’s get it started.

Why Is My Aquarium Water Cloudy?

If you really want to have a crystal clear aquarium then first you have to know the causative agents behind the cloudy water.

I know how hard and harsh it will be for you to see your aquarium cloudy and foamy. Most of the time, this phase will pass away on its own.

However, there are instances where this cloudiness will take chronic and fatal reason for the development of diseases in fish as well as bring their death.

So, you need to know the culprit behind this chaos in the tank. Sometimes it is your fault and sometimes it isn’t.

So, don’t blame yourself and read the causative agents carefully:


When you feed your fish more than necessary, the fish will leave behind the extra food in the tank.

The remaining food materials will make the water dirty and cloudy when they start to dissolve slowly in the water.

Also, the overfed fish will produce a high amount of excretion and a high level of dirt in the tank water.

The excreted materials will mix up into the water and cause the water to go cloudy and foamy.


Keeping a greater number of fish in the aquarium than an aquarium can handle will invite problems you can’t even imagine.

Topping the list of problems, a high level of excretion from many fish together will make aquarium water dirty sooner than usual.

Poor Filtration Method

Your aquarium filter and filtration method decide how well your tank water will look. So, when the filter fails to do its job, the scenario will be the same as the river where sewage water is dumped.

Sorry not sorry but never ever compromise with the quality of the filter or else you will be dealing with more than the cloudiness of water.

Aquarium filter removes the debris, dead and decaying matters, and other pollutants from the tank.

And when it is not functioning well, all these pollutants will make the aquarium water dirtier and consequently cloudy.

Dead And Decaying Matters

The dead and decaying things like dead fish, wilted plant leaves, unfinished food will mix up in the aquarium water.

The mixture will be not a good view to watch. The opaque water with all the dirt and pollutants will be hard for you to even point out the fish inside the tank.

Algal Bloom

One of the prime causes of cloudiness of aquarium water is the unnecessary growth of algae in the tank.

Trust me, a little growth of algae might be okay, but when the limit is crossed, it is a nightmare you can’t live with.

Algal bloom when reaches its peak point will make the tank seem crowded and full of pollutants.

A little algal growth is an inevitable truth however you need to be careful to keep the level as low as possible.

Algae make the tank seem like it has never been habituated in. Just remember a pond in the rainy season when the algae, as well as other plant growth, is maximum along with all the mud and extra dirty water.

That’s how your aquarium will look like when the growth of algae in the tank goes out of hand. Be careful!

Bacterial Bloom

Sometimes, cloudiness is the result of the colonization of beneficial bacteria in the tank. Within the first few days of the addition of fish in a new tank, beneficial bacteria will start to colonize in order to perform the aquarium nitrogen cycle.

I know this sounds absurd but it is a fact. The cloudiness will clear out once the fish is settled properly and the growth is substantial.


When you add woods, dried leaves, or any other substances that produce organic compounds or tannins when put into water, you will start to see brownish water in the aquarium.

The tannins secreted by many types of decoration that can help to lower the pH too can also make the aquarium water cloudy too.

Long Exposure Of Light In The Fish Tank

People often think that long exposure of light in the tank will make tank water appear crystal clear.

Oh my God, how wrong they are? If you are one of them, then step out of your delusional world and let’s face a fact.

When you let the light into the tank for a long time or all the time and even with the high input, the algal growth will increase like the colonization of bacteria in the agar plate.

Light helps the algae to grow faster, divide and grow into something bigger within a very little time interval.

How To Get Aquarium Water Crystal Clear?

Now when you know the root causes of aquarium water getting cloudy, there is no question for your wandering mind to think about solving the problem.

Making your aquarium water crystal clear is your ultimate goal, I know it. I have been through that phase where every little debris in my aquarium water bothered me to death.

I wanted all the pollutants gone in no time. But everything takes time but I did succeed. So, there is that.

I will let you in on the steps of how I made my aquarium water crystal clear. There is no rocket science to it and simple procedures will go long if you follow my instructions properly.

Trust me when I say this if you do as I say, your cloudy aquarium water will change into a clear one in no time.

Aquarium Filtration

Well, the easiest and fastest way to make your aquarium water clean or maintain the water quality is to use the best aquarium filter.

The aquarium filter decides the quality of water in the tank and also maintains the tank environment appropriate all the time.

When the physical pollutants, the dirt particles, and other dead matter are filtered out from the water through mechanical filter media, the water will automatically start to become cleaner and transparent.

Here is an article on Why Do Fish Tanks Get Dirty So Fast – How To Clean And Maintain Tanks?

Live Plants

Live plants will use up nitrate present in the tank and sometimes prevent the algal and bacterial bloom in the tank.

I know the plant may not solve the issue of cloudy or foamy water instantly but it will use ammonia and iron present in the tank.

The presence of ammonia or iron in the tank will lead to algal and bacterial bloom which will, in turn, cause the water to get cloudy.

So, you see how live plants will help you solve the problem without even doing these things directly.

Here is an article on 9 Best Low Light Aquarium Plants | Benefits of Aquarium Plants

Beneficial Bacteria In Aquarium

Aquarium beneficial bacteria in the biological filter media will clean up the ammonia and nitrite present in the tank and convert it into nitrate.

The aquarium nitrogen cycle performed by beneficial bacteria will remove the harmful compounds within certain time.

When these chemical compounds are removed from the tank, the algal growth and bacterial bloom in the tank will be within the limit.

This limit in the growth of algae and bacteria in the tank will help you clean the water way easier than it is necessary.

Water Change

If nothing works, there is always an option to change the water of the tank. Well, I am not saying you need to replace all the water at once but you need to change the water with a certain pause.

Change 20 to 30 percent of the water each week in order to add cleaner water into the tank. Removing a certain portion of the dirtier water with cleaner water will dilute the water pollutants mixture.

But remember not to overdo anything or else the sudden change in the water parameters will affect your fish health and longevity.

You might like to learn more about Is Too Much Water Change Harmful For Your Fish: How To Do It Safely?


Flocculating agents that will bind themselves to the cause of cloudy water like algae, bacteria, and other debris.

After the binding process ends, these liquid solutions with a mixture will force them to drop into the bottom of the tank.

This will help you to remove the cloudiness and foaminess from the aquarium water immediately. But I suggest you to go for natural remedies first.

Clarifiers and flocculants might not always come for your rescue and natural solutions are always best for you, your tank, and your fish too.

Clean-Up Crew

There are few fish and aquatic beings that will clean the algae in the tank as well as other dead materials.

These dead materials and pollutants are the main reasons for your aquarium water to get cloudy. Trust me, your clean up crew will even finish the leftover food in the tank with no issues.

When all these things that are responsible for causing water dirty are taken away one by one, there is no way your aquarium water will not be crystal clear.

Some of the aquarium clean up crews are my favorite Otos, nerite snails, Amano shrimp, and Siamese Algae Eaters.

You might like to read more about 30 Best Algae Eaters For Freshwater Aquarium

You will love to have these aquatic beings in your tank. They will add new beauty to the tank and of course, will keep the water cleaner.

Use Of Activated Carbon/ Chemical Filtration

Activated carbon is a blessing in disguise that will bind other pollutants with opposite charge with them.

Especially the large tannins and medications that will make aquarium water cloudy and brownish will be removed with the help of activated carbon present in the chemical filtration.

Most of the filters you purchase will have tiny or different types of activated carbon in them and hence it will filter out the tannins and medications while the water passes through the filter.

How To Keep The Aquarium Water Crystal Clear?

Making the aquarium water crystal clear is actually a piece of cake but maintaining it like that will be the hardest task ever.

I understand your dilemma so don’t you worry. I am here to help and actually very happy to help.

There are few tricks that you can follow and your aquarium will always have crystal clear water.

Follow my lead and you will do great. Do the following things if you want to keep the aquarium water crystal clear all the time:

Live Plants

Plants can actually use up many pollutants and clear the water from different types of pollutants. Believe me, you will be surprised to see the results of having plants in the aquarium.

Sometimes, nature, itself, is the optimum solution to every problem that is created due to the imbalance in nature.

Plants maintain the water quality all the time without even harming themselves or the fish and other inhabitants present in the tank.

Avoid Overfeeding Your Aquarium Fish

You can get an automatic fish feeder or follow the 2 to 3 minutes rule to avoid overfeeding your fish. Research well about the type of fish you are planning to keep in the tank.

Feed them accordingly and within a certain time interval regularly. Do not starve your fish to avoid overfeeding it.

Avoid Overstocking Your Tank

Overstocking a tank is one of the prime causes of clouding or creating foamy water in the tank.

Keep the appropriate number of fish according to the size of the tank and gallons of water present.

Do not try to act cleverly and do something stupid as pushing the tank limits or fish limits. When you keep an ideal number of fish in the tank, the chances of cloudy aquarium water nearly become null.

But you will have to take care of various factors along with the appropriate number of fish in the tank to keep the water crystal clear.

Clean The Tank More Often

Vacuum the gravel and clean the substrate more often in order to avoid any dead and decaying parts of pollutants hiding in the bottom.

Also, clearing the gravel and substrate from fish excretion or any other pollutants helps to maintain the ideal environment for plants’ roots too.

Remove Physical Pollutants

Use mechanical filter media in the filter or install the filter with mechanical and biological filter media to remove all the debris and physical pollutants and ammonia and nitrite from the tank respectively.

The constant removal of all the physical pollutants and absence of ammonia and nitrite will automatically maintain the water quality.

Weekly Water Change

Sometimes, frequent water change can affect the transparency and hygiene of aquarium water equally as the no water change for months.

So, if you want to maintain the optimum and ideal level of water quality in the tank, I recommend you to perform water once every week.

Circadian Rhythm For Lighting

Most fish love to be active during the day and rest well during the night. They bring this habit from their natural habitat to the aquarium.

So, when you are keeping the fish in the tank, follow the circadian rhythm, meaning keep the lights on during the day and off during the night.

Most fish prefer a dim-lit environment which will in turn control the unwanted and high level of algal growth in the tank.

With no algal growth to cloud the water, the aquarium water will always be transparent and clear to look into.

How Long Does It Take For Cloudy Aquarium Water To Get Crystal Clear?

I know it can get scary when your water starts to get cloudy all of the sudden. All your effort to add fish in the crystal clear aquarium water will be a dream from the past.

There are instances when the new addition of fish or the addition of the fish for the first time in the aquarium will welcome initial bacterial bloom.

And this bacterial bloom is responsible for different important processes in the aquarium. Beneficial bacteria in the aquarium helps to convert ammonia into nitrate and prevents ammonia and nitrite poisoning and nitrate intoxication.

So, Cloudy water for the first few days, from 2 to 4 days, after the addition of the fish in the tank is not harmful to your fish.

The initial cloudiness is due to the growth of free-floating beneficial bacteria initially in the tank.

Hence this bacterial bloom is not harmful to the fish and will subside on its own after a while.

However, if the cloudy water doesn’t clear out after 10 days, it is time to take measures my friend or it is even better to call the expert. The long exposure to cloudy water can definitely kill your fish.

Is Cloudy Water Bad For Fish?

The presence of a high level of bacterial bloom can also cause an imbalance in the aquarium ecosystem and sometimes cloudiness is the result of dead and decaying food.

These dead and decaying substances can increase the level of ammonia and nitrite in the tank. Hence, ammonia poisoning and nitrite intoxication.

That’s why you may have to lower the nitrate level in the aquarium. All of this can be done once you subside the aquarium cloudiness and prevent the formation of cloudy water in the near future.

Stress and Diseases will follow cloudy water once the water doesn’t clear out after a few days. Make sure to call the expert or else you will have a dead fish in the tank.

Frequently Asked Questions

I know Fishkeeping can bring in more questions than necessary. So, I tried to lower the burden for you a little. Here are answers to few FAQs that people ask randomly about aquarium water most of the time.

What Must You Add To Your Water Before Adding Any Fish?

There are few things you need to add to the tank before you add any fish. These small yet important things decide how well your aquarium will bloom and become as you want.

Test your aquarium water and filter it out well for few weeks to let it mature. Test the water for the aquarium pH, ammonia level, nitrite level, and presence of chlorine or any other chemical in the tank.

You might need to add a water conditioner that can lower the ammonia and nitrite level as well as clear the tiny hint of chlorine from the tank water.

Also, you have to acclimate your fish to the tank water before adding them to the tank. Acclimation helps the fish to adjust to a new environment easily.

Here is an article that might interest you Aquarium Decorations: What To and What Not To Add – Beginners Guide

How Long Does It Take For Tap Water To Be Safe For Fish?

Well, the main or key element that makes tap water unsafe for fish is the presence of chlorine.

But don’t worry, the chlorine present in the water will evaporate within the first 24 hours if you leave the water undisturbed.

Learn more about How Long Does Chlorine Stay In Water?

The maximum time it takes to dechlorinate the tap water is 5 days overall. Also, the concentration of chlorine in the tap water decides how long you will have to wait before adding it into the tank.

Similarly, the volume of water you are supposed to use will also decide of leaving the water to rest for how many days.

Most of the time, 24 hours is sufficient while 5 days might also be another option. Test the water once you let it rest for this time interval.

If you cannot find any essence of chlorine or any other chemical, then congratulations your tap water is safe to add into the aquarium and for fish.

You might like to learn more about Why is Tap Water Not Safe For Fish? & How to Make It Safe?


In a nutshell, everyone wants an aquarium transparent and clear with the absence of pollutants, cloudiness, or foaminess. If you are determined enough and follow few simple steps, you will have crystal clear aquarium water in no time. Remember how preventing something from happening is better than looking for solutions after the problem hits you in the face. Quit overfeeding your fish or overstocking your tank while taking care of the aquarium filter all the time. I know it seems like so much task and so many instructions.

But once you start doing these small things, you will find every task quite simple. And if you still face problems like this, drop a comment in the comment section below.

Good Luck!!!

Happy Fishkeeping!!!

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