dirty fish tank

CLOUDY FISH TANK – 10 Reasons Why and How To Fix The Problem

You look towards your fish tank and suddenly see cloudy aquarium water spreading across the aquarium glass! Your first thought might be drastic. But, if you identify the reason for cloudy water early on, there can be an easy solution. I have dealt with cloudy water before, and it’s frustrating, but leaning on those with experience in this situation helps.

Cloudy fish tank water can happen in saltwater aquariums but is more frequently found in freshwater fish tanks.

guppy swimming in freshwater fish tank

Is Your Fish Tank Cloudy?

There are several reasons why a clean tank can become suddenly filled with cloudy aquarium water. From a bacteria bloom to algae growth, the question becomes, what is the true culprit of this cloudy water?

Let’s explore…

Green Water

Green tank water is jarring, but more than likely due to algae blooms that are out of control. This type of unsightly water will take some time to clear up.

Freshwater tanks tend to cloud the most when it comes to water quality as opposed to saltwater tanks due to the natural ability of salt that creates a cleaner environment. This article will cover the why’s and the How to fix cloudy tank water quality.

Chalky or Grayish Water

More than likely, a new tank will present this condition. If that is the case, there are some tips below, to help.

8 Reasons Causing Cloudy Fish Tank Water Quality

Cloudy water is a big inconvenience but fixing cloudy aquarium water can be easily managed. Let’s start with the causes of cloudy aquarium water.

  • Poor Filtration Systems
  • New Fish Tank & New Water
  • Overfeeding Fish
  • Overcrowded Aquarium Space
  • Algae Growth From Decaying Plants
  • Dead Fish
  • The Tanks Glass
  • Substrate Not Functioning Properly

Poor Filtration

If your tank is not new, look at your filtration system as a possible cause for your cloudy water situation. Typically inexpensive mechanical filtration systems are the offenders in this particular situation. If your filter is made using cheaper foam filters, these tend to be coarse and can have trouble filtering smaller microscopic debris.

star wars fish tank decor

Filter media is something to consider when you fix cloudy aquarium water. If the foam of your filter is coarse and you have made no changes to your tank, this could be what is causing the issue. Purchasing a better filtration system for your fish tank may be needed, but a cost-effective method might be to replace the foam filter itself.

Canister filters are a good choice for fish tanks, but they also have foam inside them to filter out decaying fish matter and plants, along with bacteria.

By examining the filtration material and filter media, you can an indication of whether the filter needs cleaning or if you need to replace the filter foam for something that works better.

Is it time for the filter to be changed?

With power filters, you can also add a filter layer to help filter the cloudy water.

Blue floss for instance is perfect for such applications.

New Fish Tank & New Water

Even the best fishkeepers and fish tank enthusiasts experience cloudy water, so do not stress if it happens to you! Just the other day I cycled my aquarium and ended up in this boat, which is why I decided to create this information about cleaning up a cloudy fish tank.

With a new tank, comes new fish. As things such as fish and plants are added, nutrients, waste, and bacteria also come with them. Done too quickly and it is inevitable, that the filter won’t keep up. And, guess what? Yes, cloudy water.

fish tank cycle

On a scientific level, what happens in this scenario is that the good and beneficial bacteria procreate way too fast. This results in a quick imbalance and the nitrifying bacteria who were once good are now having a procreation party and making things look cloudy and milky.

These nutrients are what these bacteria feed on, and when there is a ton of food for them, they party. The results are population blooms that mar the tank water itself. If this is your situation as to why you think your tank is cloudy, you may be right.

The good news is, that all that is needed is a bit of patience. Slow your roll and add items to the tank one at a time, bit by bit. This gives the bacteria time to eat the food, rather than procreate or grow, to reduce the cloudy appearance of the water. You should start to see clear, un-tainted water as time marches on.

While you wait, continue to monitor the water quality of your tank. I recommend using a water testing kit like this one, which is pretty inexpensive. This way, you know you are on the right track, and you know your fish will live in a good environment to keep them alive and healthy.

Overfeeding Your Fish Makes Them Poop (a lot)

Sounds gross, I know. But every living thing must poop or at least process the energy they absorb. Like humans, fish poop too! Spoiler alert, they also pee.

With fish or aquatic animals, well they essentially swim in their own poop. When you feed fish too much, they poop more, causing the fish tank filtration system to struggle with excess food. More food means more bio-waste for the tank to clean. This puts constraints on the entire fish tank system and the environment can change to cloudy gross water in a heartbeat

This causes the fish tank environment to go off balance, but there is hope. Let your fish skip a meal for a day. This will help them return to a normal schedule and if by chance you have a hard time remembering when to feed your fish, you can purchase an auto-feeder for less hassle which leaves time for you to adore your fish tank, rather than work on it.

Overcrowded Aquarium Space

Similar to Overfeeding your fish, adding too many fish to a tank causes more nutrients in the tank and more waste material to build up. I love adding fish to my tank also, but there is a point when you have to consider removing a few fish or buying a larger tank that offers more space. These are both options that would help to reduce the cloudiness caused by overcrowding.

The age-old wisdom in fishkeeping is that:

  • You should add new fish no more than every 4 to 6 weeks
  • and not increase your fish count by over 50% at a time.

java moss for aquarium

Algae Growth From Decaying Plants and Dead Fish

Dead fish, dying live aquatic plants, and other decaying materials in your aquarium water can have serious effects on water quality. Often, when things are bad turning the water a thicker, more opaque kind of cloudy water forms. Typically it gets this bad when, sadly, a fish dies. With cloudy water, a dead fish might be hard to stop, but it is something you should be curious about to identify issues regarding cloudy H2O.

If you spot a dead fish when you have clean water, be sure to remove it as soon as possible to avoid excessive nutrients causing a massive green water explosion. Check your tank on the regular and also consider breeding fish as not all of the babies live and can be contributing to cloudy tank syndrome.

Also, keep a sharp eye on uneaten food. If your fish are not “cleaning their plates” then chances are this type of fish waste is causing beneficial nitrifying bacteria to reproduce exponentially, causing a bacterial bloom from excess nutrients, a bacterial blossom, or dissolved constituents.

Before a bloom starts, you can also examine your substrate for particles of uneaten food. This may indicate, that you are also feeding your fish too much, as mentioned earlier in the article.

pest snails

Removing Biofilm From Fishtank Surfaces.

One thing that can make a fish tank look dirty is the glass itself. Obviously, glass, when kept clean, can give a clear crisp view of whatever is beyond it. In this case, biofilm buildup can make your water look dirty as you look through the sides of an aquarium.

You will typically notice biofilm first on objects in your tank like lava rocks and driftwoods. If you see this then it is likely there is some buildup of biofilm on the tank’s glass.

This is a rather easy fix and should be something that happens on the regular anyway. Time to clean the fish tank.

neon tetra 10 gallon tank

Aquarium Substrate Can Make A Fish Tank Cloudy.

Got a new substrate for your fish tank? Great, but don’t forget to thoroughly rinse it before you add it into the aquatic tank. This has happened to me frequently. I always rush through the process. Simply, don’t do it and take your time. This will eliminate the possibility of cloudy water in this example.

Another cause of a cloudy fish tank because of a substrate is that it may have been jostled about. Large fish can easily maneuver to irritate the placement of the substrate causing clouds of milky water to rise and make the appearance of your fish tank less than desirable. Or, perhaps you had your hand deep in the tank and stirred things up a bit.

Either way, ensure, your substrate is anchored to something. Anchored more the better. This can eliminate some of the guesswork when trying to figure out why my fish tank is dirty!

Easy Ways to Fix Cloudy Aquarium Water

Knowing what caused a cloudy tank to be cloudy is only half the battle. Here are some ways to prevent and manage cloudy fish tank water situations.

Maintain Your Fish Tank

Easier said than done, but you made the commitment to take care of fish, and maintaining your tank is part of that commitment.

  • Change your water frequently or if it becomes cloudy. Bacteria blooms are manageable if you stay on top of cleaning the tank’s aquarium water.
  • Remove excess food from the substrate. They make special vacuums that can make this job easy.
  • Clean Your Glass. Use fish-approved cleaners, a scrapper, or anything that removes biofilm such as specially made products like these.
  • Maintain Your Filter System. Refer to your model’s user manual for cleaning is important and will give you everything you need to know. Just think a clean filter, equals a clean tank. This will improve the state of your beneficial bacteria.
  • Cycle the Fish Tank. Typically this is a must with a cloudy fish tank.
  • Use a kit to test the water. They are fairly inexpensive and will help your fish thrive and be happier.
  • Adjust Lighting and Light Quality. Making things brighter can give your aquarium a more interesting feel. It will also help things to look less cloudy.
  • Add an activated carbon media. Helps reduce nitrate levels.
  • Use a gravel vacuum. Helps to remove uneaten food, particles, and other debris that causes bacteria bloom.

Cloudy Water (FAQS)

Why Is My Fish Tank Cloudy?

Fish tanks are supposed to replicate natural aquatic environments, and in doing so, they need a balance of nutrients, PH, and other important factors. With so many variables in play, if one goes out of wack cloudy fish tanks can result.

Can Cloudy Water Hurt Fish?

Not usually, but cloudy water can be a sign of bad things to come. Left unattended and your fish may suffer.

How Do I Make My Aquarium Water Consistently Clear?

Great filtration, maintenance schedule, and keeping your stock levels stable are the best ways of keeping your aquarium water sparkling clear. UV sterilizers are also helpful in keeping green cloudy water, crystal clear. Throw in a carbon filter to keep tiny particles contained and nitrate levels completely safe.

Does A Filter Clear Up Cloudy Water?

Filters work hard at clearing up your water. It is the main function of a filter system. Filter systems do have the ability to do so, and new filters need to cycle through a tank a few times to catch up, which could be a cause of the cloudy water. Even in an established aquarium, a filter system can do the job. You should however investigate the cause of the cloudy water before relying only on a filter to clear things up.

A Clear Tank Is Possible

In conclusion, don’t freak out if your fish tank becomes cloudy. There are several ways to fight back, and after about a week of scrubbing, cleaning, and learning, your tank will be just fine and your fish healthy.

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