Cloudy saltwater tank: The ultimate guide to get rid of it

This entry is part 2 of 3 in the series How to get crystal clear water

Well, everyone prefers a hassle-free environment for their saltwater fish. Naturally, the inevitable idea of cloudiness in our aquarium freaks us out. It is not a new thing. Who doesn’t like a clear aquarium? We all want a perfect aquarium for our fishes. How can you banish such expectation from your heart?

The sore truth is that there are circumstances in which the cloudiness of your saltwater aquarium becomes unavoidable. Somehow, you figure out a lot of filthy materials in your aquarium and you are left to wonder. How did this happen?  You may not know. Your saltwater aquarium water may be cloudy for a variety of reasons. However, you would figure those reasons as you proceed.

1. What makes your saltwater tank cloudy?

Maybe you don’t know, you might just be the one who fired up cloudiness in your saltwater aquarium in the first place.

What am I talking about? Debris may have set off especially during your daily maintenance. How does this work?

In the course of your daily aquarium maintenance, some gravel beds or sand may have settled in the water.

You can consider this. You washed your aquarium walls. In a twinkle of an eye, you find out that some insufficiently washed gravel settles in your water .

This is simply not all. Most times, some fishes would dig within the sand and this often causes some contaminants to spread into the saltwater aquarium.

So, the inevitable result is usually dirty saltwater water.  Of course, we often experience such things as human beings. Sometimes after you have taken your bath, you may be surprised that there is still some heap of trivial rubbish hidden somewhere around your body.

Sounds frustrating. Isn’t it?

But wait, there’s more?

Sometimes, debris accumulation may not be the actual cause of the cloudy feel of your saltwater aquarium. Sure enough, there may be more reasons for it. You may be surprised that these reasons are not exhaustive. So, I am going to show you some of these reasons below.

Bacterial bloom

Maybe you just started out and your tank is brand new or you have started an aquarium enterprise for a while and you have recently added new tank. Most likely, this could cause cloudiness in your water.  

Have you tried to wonder how?

Most certainly, your aquarium needs bacteria.  This is because the cycle of ammonia to nitrites to nitrates definitely takes place when a bacterium is in the scene.

What am I talking about? It is bacteria that convert ammonia to nitrites with its end product being nitrates.

So where are we going? The presence of bacteria alone in your aquarium takes compounds that are poisonous to your fishes and converts them into less poisonous substances. In the aquarium world, this process is called a “cycle”. When I say cycle, it means that the bacteria cycle your aquarium.

See also:

How to Master the Nitrogen Cycle of Your Aquarium

What’s more? The more you add more fish or other livestock to your aquarium or even feed them, the more waste it generates in the water. When it does, the bacteria increase. This is what is called ‘bacterial bloom’.  So what’s the problem here? 

With an intense increase in bacteria, your water gets cloudy and turns milky white in a few days. Sometimes, the color of a bacterial bloom may be brown. This is how a bacterial bloom operates.

Practically, the cycle doesn’t even end in that manner. The clarity of the water is almost close to zero but no visible floating substances. Later on, your aquarium keeps going through several cycles which may make it even cloudier.

Algae bloom

Well, a bloom in algae could also make your water cloudy.

So what causes an algae bloom?

There may be the bloom in algae when there are excessive nutrients in your aquarium most especially phosphorus and nitrogen.

The colors of a typical alga are usually green, red or yellowish-brown. The next time you see any of those colors on the surface of your aquarium water, it is probably algae.

So where are we heading to? With the increased growth of algae in your aquarium water, your water becomes cloudy. In worst cases, your fishes may not survive. Worst aquarium scenario like the death of fishes caused by algae could accumulate to cause cloudier water.


Maybe you don’t know, your saltwater aquarium may be cloudy because calcium carbonate deposits right inside it.  

Calcium carbonate is often the most common form of precipitation that occurs in an aquarium. You would most likely see the formation of the precipitation in your tank heater or even pumps.

Still wondering why?

Maybe of all mineral elements, it is calcium carbonate that gets to precipitate in your saltwater aquarium.

Well, you may consider that for sure but calcium carbonate precipitates in your aquarium and makes it cloudy when there is excessive calcium. Your saltwater aquarium may also be precipitated by calcium carbonate when it lacks magnesium or the pH level of your aquarium is high.

What’s more?

Care to know how this lack of magnesium tends to stir up calcium carbonate precipitation to the point of messing up the look of your saltwater aquarium?  

Let me say this straight.

Some magnesium spreads across your water.

It didn’t just spread. It occupied the area that normally would have been invaded by calcium. Then the magnesium ions shield the surface against the precipitation of calcium carbonate.  Imagine the kind of torture your aquarium water would face with little or no magnesium.

It is this chemical assault that makes your saltwater aquarium gets cloudy.

See also:

Basic Killer Tips on Aquarium Water General Hardness


Maybe in the course of your routine maintenance, you decided to add some fine sand to your saltwater aquarium.

Well, you didn’t add it to an empty aquarium. You just felt that the sand would be a great addition to your water-filled aquarium.

Sometimes, this is simply not all. Maybe you added some glass containers that fires up the sandstorm?

Did you install a water pump that directly points down to the sandstorm such that the sand bed spreads into the water?

Well, the pump installation that pointedly stirs up the circulation of sandstorm in your water may not be intentional. Whatever it is, the circulation of sand bed may stir up cloudiness in your fish tank.


It is very simple to tell. When it comes to the look of your saltwater aquarium, microbubbles could be your arch enemy.

Still wondering how this microbubble thing comes into the scene?  Sure enough, there are varieties of reasons why your aquarium could form some bubbles.

It may be that you haven’t properly set up your skimmer.

The resultant effect of an improperly adjusted skimmer is usually that there will be too much turbulence in your water. Once there is water turbulence, the water in pipes seeps down from the tank to sump in a forceful manner.  

Sometimes, the water seeps from the sump to the tank. It may also be that there is a huge leak in the skimmer that is forcefully stirring up water flow when it is not supposed to do so at that moment. Once this happens, your water is going to form some bubbles and it doesn’t look like one that can stop anytime soon.

What’s more?

Of course, bubbles aren’t a bad score for your neither your fish nor saltwater tank. This is because it aids gaseous exchange in your aquarium water.

Don’t tell me your water does not require a bit of crashing waves sometimes. But the sad truth is that if you have excessive bubbles in your saltwater tank, it will make it look like white soapy water. You might not want such an ugly look for your tank.         


Of course, spawning may not be one of the most common causes of a cloudy saltwater tank but it is as significant as other causes. Hey, the effect of spawning on your saltwater aquarium could be ridiculously wild.  

Does this sound silly? No, it doesn’t.

Consider the fact that your fishes deposit eggs in your aquarium, you can visualize what will likely come out of it. Your tank gets screamingly white as if it is releasing milk water. It can even get worse when your fishes deposit the eggs en masse.

What’s more? Sometimes, spawning could be a sign of a healthy fish or tank maintenance. Sure enough, it could be. In the same breath, it could also be a bad sign that your aquatic beings aren’t in any way healthy. So when your tank gets even white with an unhealthy spawning, the results are more disastrous.

2. How do you get rid of your cloudy saltwater tank?

More often, you don’t have to adopt any special strategy to get rid of your cloudy saltwater tank. This is because the cloudiness may vanish with time. In the same breath, the possibility that the cloudiness will disappear itself could be close to zero. Sometimes, you may have to take extra steps to ensure that your aquarium bounces back to its normal fresh look. This is especially when the cause of the cloudiness is not the mere dirt.  

This is why a lot of treatment methods have been garnered to ensure that your aquarium can be clear again. Note that different treatment applies to each cause. Therefore, the treatment methods will be based on that which applies to each of the causes.

Treatment Methods

Bacterial bloom

Water Change

Well, you may not know. A water change can go a long way in making your cloudy tank crystal clear. All you need to do is a 20-30% change in your aquarium water. While you do that, you should focus on reducing the excessive fish food and debris out of the sand bed.

Reduction in fish’s food intake

If you are fond of overfeeding your fish, you should reduce it so that your water can regain its clarity. Possibly, you can prevent subsequent bloom with this method.

Filter check

One of the most promising ways you can fix a bacterial bloom in your aquarium is to ensure that your filter is properly set up for your tank. One more thing. You should figure out whether the filter fits in with your fish stocking level too.

See also:

How to choose the right type of filter for your aquarium?

Enzyme mix

If you have adopted a long list of treatment methods and your water did not regain its nice look in a few days, you should try some enzyme mixtures.

Nutrafin’s Bio- clear is a good catch for the fixing of bacterial blooms.

But let me be honest with you, you still have to scan through the feeding level and the status of your filter before you can truly see the effectiveness of enzyme mixes.

Algae bloom

UV filter

While you are at it, you can well add a UV filter. Definitely, the less harmful bacteria that your aquarium need will occupy the algae area so that your water can get clear at once.

Precipitation ->pH check

Well, there is no precise answer as to how you can get rid of calcium carbonate precipitation. It definitely depends on whatever you must have added to your aquarium before or during the precipitation.

So, you should ask yourself these questions.

Have you added excessive lime water to my aquarium? If it is in affirmative, leave the water as it is. The cloudiness will disappear on its own.

Have you checked the pH level of your water? Is it too high? If yes, figure out a way to reduce it or seek advice from an expert.  

This is because lowering the pH level of your water eliminates existing precipitates of calcium carbonate. Practically, you can reduce the pH of your water to 7 or less. Its essence is to prevent subsequent precipitation of calcium carbonate.


Micron filter

Most people prefer to add a micron filter to clear the cloudiness at once. It often works effectively.

Adjust Water Pumps

Alternatively, you can well adjust your water pumps and let the water flow freely, the sand bed will dissipate on its own.


Check your skimmer

Sure enough, reducing the excessive bubbles that mess up the look of your water is quite simple. All you need to do is to do a quick survey for your skimmer.

How do you go about it? Try to figure out how your skimmer brought about the excessive water bubbles.

Ask yourself these questions.

Did you adjust the skimmer properly?  

Is there a leak somewhere around the skimmer?

Maybe there is a particular way in which your skimmer should be positioned. It may be that the skimmer needs to be a bit closer to where the water enters the sump so that the bubbles can form before it seeps from the sump to the pump.


  • Water change
  • Removal of dead livestock

Final thoughts

The issue of cloudiness in saltwater tank has always been a persistent one. So when you have a similar issue with your tank, calm down and try to figure out the source of the problem.

This is because everything you do with your fish or tank will always have an intense effect on either your fish or tank.  Therefore, it is always essential to scan through everything of your routine activities so that you can properly figure out the right clues to solve the cloudiness problem.

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