Why is My Fish Tank Cloudy? Causes and Solutions

fish tank

A cloudy fish tank is probably the most frustrating complaints new aquarium owners have. As an aquarium owner, all you wanted is a beautiful transparent fish tank you can come home to every day.

But, no, it seems the water in the aquarium has its own mind. One day, it was clear with your stocks active; the next thing you know, it has turned milky white or grayish in color.

Out of panic, you tried so many quick fixes to get the water cleared. It worked but only for a short time. After maybe a few days or weeks, the cloudiness is back, but this time, with such vengeance you couldn’t even see the background of the fish tank anymore.

Distraught and ready to throw in the towel, you went online and to chat forums. For the first time, you heard about “new aquarium syndrome.

You Googled the term and realized; the cloudy water you’ve been experiencing is just a typical symptom for breaking your aquarium in.

So now you’re looking for solutions to the cloudiness, and that’s why you’re on this page.

Right off the bat, an aquarium UV sterilizer should do the trick and clean that nasty water for you in a couple of days. However, scroll down to better understand the phenomenon and learn how to properly take care of your fish tank.

Before we go into the solutions for a cloudy fish tank; let’s talk about what causes it.

What causes cloudy aquarium water?

You see, a whole lot is going on once you set up your fish tank. You’d try as much as you can to make the aquarium mimic the natural habitat of the fishes.

This means, managing the water PH level, introducing bacteria into the water, maintaining the right temperature, ensuring the water has its constituents in the right quantity, and of course feeding the fishes.

All these interplays to cause the early stage cloudiness that new aquarium owners observe. Without adequate knowledge of what to expect, it can be freaking depressing.

Another vital thing to keep in mind is often, the gray water disappears without you having to do anything. They last anything between a few days to one week.

Now we’re clear on those, what exactly causes milky-white fish tank water?


Gravel residue

All aquarium setup manual has instruction on how to thoroughly wash gravel substrates before introducing them to the water.

But, most times, aquarium owners don’t sufficiently wash them. Hence, debris on these gravels gets introduced into the fish tank. This debris floats around the water resulting in the hazy overcast.


Dissolved water constituents

Cloudy water could be as a result of the high level of constituents in the water. Dissolved silicate, phosphate content or the presence of heavy metals in the water also contribute to the murky fish-tank water.

It’s essential you test the water for alkaline to determine the PH level and take appropriate steps to return the PH to equilibrium.


Excessive feeding

Uneaten food in the water could cause it to get murky. In fact, overfeeding the fish is a major cause of cloudy aquarium water. These leftover feeds encourage bacteria bloom which in turn leads to the gray coloration of the water.

Related to the above point: leaving dead plants to decay inside the aquariums also encourages the blooming of the bacteria which inadvertently leads to murky water.


Addition of supplements

The introduction of bacteria and other supplements into the water also leads to getting them foggy. However, you should expect the water to clear in a matter of hours.



It’s a no-brainer, the higher the number of fish in your fish tank, the more considerable waste they’d produce, and the more food these bacteria will have. So overstocking the aquarium, encourages the proliferation of the bacteria that would sully your fish tank water.



Your aquarium water can get hazy if you neglect to take care of it. This is especially true for new fish tanks; since you’re required to change the water at least two times a week until the filter bacteria get established.

Inadequate water changes are a recipe for encouraging critters to overrun your aquarium.


No fish yet my fish tank is cloudy

If it happened that you’ve not added fish to your aquarium yet you notice the water getting hazy, then it could be due to the decorations and or equipment in the water. This could be as a result of not washing them thoroughly. Don’t panic, continue with your regular water changes, hopefully, it will clear out on its own.

However, if it doesn’t clear it might probably be, they’re not aquarium safe and dissolving in the water. They should be removed, and a wholesale water change is done.


Solutions to cloudy fish tank water

We’ve seen several factors that could make aquarium water appear murky; let’s now talk about how to get the water crystal clear.

Wait it out

Hazy fish tank water is often part of the natural process for setting up an aquarium. Hence, there’s nothing you could do than to have patience and wait as the cycle runs its full course.

The settling of the filter bacteria on the substrate typically takes a few days after which the water becomes crystal clear.

If out of panic, you tamper with the process or add a chemical, it might actually clear it for just a few days then the cloudiness will return, hence the recommendation to allow the process run its full course.


Thoroughly wash the gravel

If the murky water is as a result of having insufficiently washed gravels in the aquarium; then draining the tank and rinsing the gravels until the water runs clear should be sufficient to get the water cleared.


Test water and treat with conditioner

Grayish water due to a high level of constituents can be cleared by using conditioners. First, test the water to determine the PH level, this helps you identify the kind of conditioner you’d need.

Another option with additional benefits to consider when handling a high level of constituents is to use Reverse Osmosis (RO). You can easily get it from your local fish shops or ask for units that are capable of RO.


Add good bacteria

Seeding your tank with good bacteria helps get the natural process going since the bacteria will be on the ground to feed off the cloudy causing bacteria. Simple ways to add bacteria to your aquarium water include purchasing a prepackaged bacteria culture, using gravels covered in bacteria or even introduce live plants to the fish tank.

Plants serve dual purposes; they act as natural filters and also host to colonies of bacteria that form the basis for the aquarium ecosystem.


Maintain your filter

The filter is the lifeline of your fish tank – it enables you to change water, flush out uneaten, dead, and other organic waste from the water.  So neglecting it means you’d be running the risk of bacteria and algae blooming, murky water and even having your stocks contract diseases.

One tale-tell sign that your filter needs maintenance is once you notice the pressure of the water running low.

Follow the manufacturer’s instructions when maintaining the filter. Remember, don’t wash the filter, just rinse with clean water and insert back.


Change water regularly

For new aquarist, this is probably the most intimidating part of starting a fish tank. However, with the latest development in aquaculture, it’s a breeze.

Remember, the goal is to recreate as close as possible the natural habitat for the fishes, so changing the water regularly keeps the water fresh, just as flowing water would.

The recommended frequency is twice a week and about 20-25 percent of the water. For a new aquarium, the rate could be higher.

Water changes are the easiest way to maintain good water quality and to ensure dead, waste, and other critters get flushed out of the water. Also, remember to check the new water temperature to ensure it’s close to the one in the tank.


Don’t overstock/feed the fish

It’s tempting especially for new aquarium owners to feed their stock as much as they can. However, this poses some problems one for the fishes and in maintaining good water quality.

You don’t have to feed your fishes two or three times daily, one well-timed ration is enough. Overfeeding can pose health challenges for them since they’re not designed to handle that much food.

So when planning their feeding schedule; consider adding one or two fast days in a week.

Also, don’t try to cover every inch of the fish tank with stock. The recommended stocking rate is to have one inch of fish per two gallons of aquarium water.


Wrapping it up

Cloudy water is a challenge prevalent in new fish tanks. However, a vast majority of this cases can be resolved by constant water changes and been patience. While at it, ensure to adhere to best practices like feeding the fishes lightly, ensure the filter is functioning optimally, and that your fish tank is not overstocked.

Previous articleBest Aquarium UV Sterilizers for Crystal-Clear Waters in 2020
Next articleSpeed of Light – The Beginners Guide
Passionate about everything that shines, settled down on UV(ultraviolet) lights. I'm motivated and with a mission to help people live a better life!

No posts to display


Please enter your comment!
Please enter your name here