Why do I have cloudy fish tank water? Complete Guide - Swell UK

Cloudy aquarium water affects so many fish tanks. Here are some of the issues that cause it:

New aquarium gravel

The most common cause of cloudy aquarium water in new fish tanks is the gravel. When aquarium gravel and sand is brand new it will contain some dust. All new fish tank gravel and sand should be washed vigorously in a bucket, with tap water, until the water runs clear. If gravel isn't prewashed before being added to the tank, when you fill it with water, the water will go cloudy.

The solution

Always give aquarium and sand an extra long rinse when bought new. You'll rarely get it completely free of dust, but you can deflect water through a kitchen colander or onto a dish when you fill the tank, disturbance and cloudy fish tank water with be lessened. Plug the filter in after filling and water should clear of dust within 24 hours. Fine filtering materials like filter floss will aid mechanical filtration and speed up the clearing of the cloudy water.

If it still won't clear you can use a flocculant. Flocculants cause tiny particles to clump together into larger lumps, sinking to the bottom or being removed more easily by the filter. 

Aquarium bacterial bloom

If it's not the gravel, the cloudy fish tank water may not be from tiny particulate matter. It may be bacteria bloom. Bacterial blooms are common in new aquariums less than six weeks old, when the biological balance is not fully established. Millions of tiny bacteria may be present, but it may be loose in the water column, instead of in biofilms inside the biological filter. The result is a cloudy aquarium which won't clear, with no apparent cause.

The solution

Ensure that your filter is large enough for the aquarium its running, and that it has a biological media chamber. Test aquarium water to ensure that no ammonia or nitrite is present (indicative of an immature aquarium,) add a flocculant, and some filter starter. If ammonia and nitrite is present, stop feeding, add an ammonia detoxifier, some filter bacteria, and change some water to relieve the stress on the fish.

Uneaten fish food

Most fish foods shouldn't make the fish tank cloudy but some oily, protein rich foods can. Uneaten foods often cloud water too, and uneaten food is often a sign of overfeeding or excess food, or that the fish are sick from disease or bad water quality, and are off their food. 

The solution

If the food is clouding the water, try a suitable food from another manufacturer. If the food is usually ok but is clouding when left uneaten, remove it with a net or a gravel vacuum. Test water to ensure that it's ok, and observe your fish for any signs of disease. If water parameters are adverse, perform a water change and add some beneficial bacteria. Ensure you don't have too many fish.

Dead aquarium fish

A dead fish, snail, shrimp or rotting plant can cause cloudiness in the water. Dead fish corpses break down very quickly in tropical fish tanks and if they are sizeable, or a few have died at the same time, the result can be polluted water. 

The solution

To fix cloudy aquarium water, lift up ornaments and decoration to search for any dead fish, and if you find any, remove with a net. Test the water and if ammonia or nitrite is present, do a 50% water change, and add some filter bacteria. 

Fuzzy aquarium driftwood and bogwood

There are many interesting types of wood now available, although some can develop a fungal growth when first submerged, and cloud water.

The solution

Pre-soak the wood in a separate tank or bucket until the wood sinks, and there is no further sign of fungal growth. Wood can be boiled to kill off any live fungus before being placed into the tank water, and activated carbon will help to remove any staining and cloudiness. After a few months, all fungal growths should stop, due to the last remaining nutrients in the wood, soaking out into the water.  

Cloudy Water is something all fish keepers experience at some point. Resolving this can be difficult, but luckily Swell UK has a variety of products available to help resolve this concern. Cloudy water treatments and filter bacteria are the best recommended methods to provide an easy resolution for any water-based difficulties you may experience. See our product page to shop around for items we have available.