Why Does My Fish Tank Get Cloudy? Here Is Why And What To Do

why is my fish tank cloudy help 1
Image source: reefbum.com

So, you just brought home your new fish tank that you were so excited about, and voila! After sometime, it starts getting hazy. Bad day for any tank owner.

This REALLY can be overwhelming. But here’s the good news: this is most probably TEMPORARY, and not an emergency situation. So just take a sigh of relief, as a better understanding of the etiology will help you tackle the situation, and very likely help you avoid it to happen again the next time.

We have surveyed most frequently asked questions by the tank owners who encountered a similar situation, and after some research we have found the most commonly reasons your tank turns cloudy, and best remedies for it.

I just brought a new tank, why is it cloudy?

Okay, ever thought about “gravel residue”? Yes! This can be one of the leading causes of new tanks being hazy. While you brought the new tank, you might not have washed the gravel, and all the dust and residue over it might have just been mixed with the new water.

How do i fix my cloudy tank?

In this case, all you really need to do is waste the water, let some water run over the gravel, until the water is clear. Tada! The problem is solved! Now you will have clear new water tank.

What is “tank cycling”?

If you have ever taken biology class, you must have heard about the “NITROGEN CYCLE”. You must have probably also heard about harmful and good bacteria. Well, applies in this situation as well.

Whenever there is a new tank, there is a “BACTERIAL BLOOM”. The bacterial colonies have begun to form. During the first few days, the bad bacteria that are turning the tank hazy will outgrow the good bacteria. After some days, the good bacteria will start to form and outgrow the hazy bacteria. Simple as that!

What should i do during tank cycling?

Practically, nothing! You heard it right. Let the natural cycle complete. Let the bad bacteria have some fun till the good bacteria build some army for some commando action. So just sit back, relax, wait and watch!

What is the role of the “filter”?

If you think your filter is not doing its job and want to change it before 30 days, think again. Most of the times it’s just not your filter. It’s your tank going through the natural cycle. It is also important to allow some time for the filter so that the good bacteria colonies can build over it.

Should i change the filter if my tank gets cloudy?

If your filter is not older than 30 days, then no. You should just keep it clean and maintain it well.

What chemicals cause cloudiness of tank water?

Some studies show that higher amounts of phosphates, silicates and heavy metals present in the water can cause it to turn hazy. Moreover, some of the chemicals added extrinsically, like calcium etc can also cause the same.  The pH of such water is high (i.e. alkaline)

What can be done to avoid these chemicals?

The best way is to ask your retailer about RO (reverse osmosis water). These waters have a balanced amount of all the nutrients.

Is there too much fish in my water?

Overpopulating your tank can cause haziness. Yes, too much fish means too much waste product for the filter and bacteria to clear. Also, it causes excessive amount of ammonia from the fish waste.

How much fish should i keep?

You can keep as much fish as you want! But it all depends on the size of the tank. Always start with less and then increase gradually. But keeping too much fish in a small tank is a bad idea and requires a lot of maintenance. 

Am i feeding my fish too much?

The answer is again pretty much the same. If you are feeding your fish too much or too frequently, the amount of waste product to be cleared up will increase.

Really guys, fish are small people. They have tiny stomachs and little food needs. Just give them a break. Don’t feed them all the time or too much.

How often should i feed my fish?

You should most probably feed your fish every alternate day, if not more. Some fish can even survive for more than 3 days without food.

When should i change my tank water?

You should change your tank water sparingly. There is no need for aggressive changes. 10-15% water change once a week is usually enough.

Is my tank too old?

Well, if your tank is old and it still gets cloudy sometime, there is a need for a more frequent water changes. There must be an accumulation of waste products over time.

Should i use water clarifiers?

Some brands of water clarifiers (flocculates) work well. While others are responsible for a cloudy tank themselves. Think well and look for reviews while selecting the best product.

What is seeding?

Some retailers/tank providers recommend seeding. They can provide bio sponges, wheels etc. that would be kept floating in established tanks. These are beneficial supports for building new bacterial colonies.

Help! None of the above methods worked.

Okay, as a last resort, there might be some equipments in your tank that need some cleaning. Like some decorative item. If nothing else works try cleaning all the foreign objects, and let us know about the results.


Having a fish tank turn cloudy can be concerning for any tank owner, but every problem gets easier with the better understanding of underlying problem. Usually there is nothing to worry about, and just a little maintenance is all it takes. By using one of the methods above, and avoiding the causes, improved results can surely be seen. We wish you clearer tanks and happy fish!

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