How to Clear Up a Cloudy Fish Tank
A cloudy aquarium can make it difficult to enjoy your fish tank. In this article, we explore the many reasons why your aquarium may look hazy and how to clear up the murkiness as quickly as possible.
First, pour the tank water into a cup or bucket that’s solid white inside. This will let you examine the water’s color and cloudiness without interfering.
1. Particles in Water
The cloudiness in water is usually caused by excess food, fish waste, dirt substrate, and other miscellaneous materials. Tiny bits of substrate might float into the water column, for example, when installing a new tank or setting up aquarium plants. The powder usually settles or is collected by the filter within a few days. However, if the problem persists after a week you might need to make multiple large water changes or thoroughly clean the tank.
Rinse the substrate
Till all silt is gone.
If the aquarium has not been cleaned in a while, then setting a regular schedule for tank maintenance will help remove the excess waste so that the water remains consistently clean and clear. To clean the aquarium substrate and change the water, we recommend using an aquarium siphon . (Read this article for a step-by-step guide on how to use a gravel vacuum.)
Also, don’t forget to clean the filter once every month. Your filter is like a garbage can for collecting waste, and when it gets full, it can no longer collect particles from the water. Use a sponge filter to get rid of the accumulation. Keep in mind that water can remain cloudy after cleaning the tank and filter. The filter will then have a chance of re-gathering the floating specks.
If you regularly clean your aquarium but still have murky water, it may be caused by the foods you feed. Messy fish foods (typically the kinds that contain very few binders) can turn into dusty fish poop that breaks apart very easily in the water. Instead, try to feed “cleaner” foods – such as live foods or single-ingredient, frozen foods like frozen bloodworms – that will get gobbled up quickly and turn into more cohesive fish waste.
If you keep eartheaters and other bottom feeders, they tend to stir up the substrate as they search for food at the floor of the aquarium. If they perpetually cause cloudiness in your aquarium, you may need to add more mechanical filtration to scrub the water. Mechanical filtration refers to any type of filter that physically removes debris from water. It is similar to a coffee filter. Hang-on-back, canister, undergravel and sponge filters all help with mechanical filtration. For a customized filter, you can use a prefilter sponge to cover your intake tube. To catch larger particles, you can also use a coarse sponge pad and a fine poly pad. (Fine poly pads are not reusable and should be replaced when they become clogged with gunk.) Additionally, you can improve water circulation with power heads to eliminate any dead spots in the aquarium and make sure any loose particles get sucked up by the filter.
Water clarifiers are also available to remove debris-laden water. These filters contain a chemical or clay that bonds with suspended particles. This causes them to clump together and get caught more easily by the filter or settle to the substrate. Water clarifiers stick to the particles to make them larger, so cloudiness can often look worse before the filter can collect all of it.
2. Bacterial Bloom
Now if you’re looking at the tank water in a white cup and it looks like diluted milk (with almost no visible particles), you may be dealing with a bacterial bloom. The bacteria colony reproduces rapidly when there are too many nutrients in the water, but not enough beneficial bacteria. The water looks like someone has poured milk into it. (For more information on what is beneficial bacteria, read our guide to the aquarium nitrogen cycle.)
When there isn’t enough beneficial bacteria in the aquarium, or when a large number of fish are added to it suddenly, bacterial blooms can occur. It can also happen if a significant portion of the beneficial bacteria is removed or killed – such as by repeatedly changing large volumes of tank water, overcleaning your filter (especially if it hasn’t been serviced in many months), or using certain medications that are not safe for beneficial bacteria.
It is easy to do nothing. Do not add UV sterilizer to the water or make many water changes to get rid of the haziness. This will only prolong the bacterial bloom. Wait one to two weeks and the water will slowly clear up as the bacteria rebuilds itself.
3. Green Water
Cloudy water can also be caused by bacteria. An algae bloom is when your tank water turns a dark green color or your aquarium appears to be full of pea soup. The algae bloom is tiny and free-floating and can be very beneficial for raising fish. It is a great food source for fry and prevents larger fish from preying on them. Unfortunately, it also prevents you from seeing into your aquarium and can potentially block light from reaching your plants.
Green water is often caused by a combination of too much light and too many nutrients (often coming from excess food, fish waste, and fertilizers). Green water is not able to be removed with fine filter floss, large water changes or even giant water changes. Since algae requires photosynthesis to make food, some people recommend doing a large water change, turning off the aquarium light, wrapping a blanket around the tank for 7 to 10 days, and then doing another large water change afterwards to take out the dead algae. (Green water can survive off very little light, so make sure the aquarium is completely blacked out.) Be careful with this method because your plants may suffer from the lack of light. The dead algae can cause ammonia spikes that can harm fish and other green water blooms from excess nutrients.
We recommend that you get a UV sterilizer instead of the blackout method. You don’t need a huge one to treat green water. The UV actually changes the cell structure of the algae so that it can’t reproduce. Once the algae has been sterilized you can perform multiple water changes to remove any remaining green water. Your water will soon be clear again.
4. Brown Water
Tannins are an organic compound found in catappa leaves and driftwood. This is why your tank water may have a brownish tint instead of being green or milky-white. Tannins are often used to keep and breed certain fish that prefer blackwater environments, but most people prefer to keep aquariums with crystal clear water.
As long as you don’t add any additional sources of tannins, manual water changes can gradually remove brown water. You can speed up the removal of tannins from driftwood by boiling or soaking it. These methods may not work. You can try chemical filtration, such as activated charcoal in a bag, carbon pads or Seachem Purigen in a hang-on back or canister filter. Activated Carbon can build up tannins and toxins over time, so it must be disposed. Purigen, on the other hand, is reusable and can be “refreshed” with bleach to remove the impurities it collects.
5. Cloudy Aquarium Walls
If you don’t see anything in your white cup of tank water, it could be the aquarium walls causing the problem. Make sure the main viewing panels are clean by using an algae scraper to scrub the inside. Then, wipe the tank’s exterior with an aquarium-safe cleaner. Make sure to use an acrylic-safe scraper to avoid micro-scratches. The glare from lights can cause haziness in your aquarium. You can add an aquarium background to the tank’s interior or exterior.
Are you unsure how often your fish tank should be cleaned? Our free guide will show you the best water changing schedule for your aquarium.