How to Uncloud a Goldfish Tank

Never pour the water from the pet store into your tank. You could introduce bacteria and parasites.
i Goldfish image by hannahfelicity from

Goldfish are entertaining to watch and, as far as pets go, easy to care for. When the tank turns cloudy, however, it's frustrating for the beginning fishkeeper to know what to do. Cloudy water can be cleared up with a little patience and kept at bay with simple routine maintenance.

Causes of Cloudiness

thenest article image

goldfish image by martin schmid from

In order to determine the cure, you need to first figure out the cause. Cloudiness can be caused by any number of culprits. If the water is a greenish cloudiness, it's an algae problem. If it is foggy or looks like you are looking through a frosted glass, it's a bacteria bloom. If the tank is dirty, the cloudiness may appear grayish or yellowish. Each of these causes has a specific remedy.

Specific Remedies

thenest article image

Water lilies at the flower market image by Stéphan SZEREMETA from

If you think you may have an algae problem, there are several things you can try. Purchase some algae-eating fish or snails who will eat the algae on the sides of the tank and keep it clean. Try scraping the algae with an algae scraper, and purchase algaecide chemicals. Make sure the tank is not in direct sunlight. Add a UV light if the problem does not resolve. If the problem is bacteria, add a broad-spectrum antibiotic such as minocycline, available in pet supply stores. Be patient, it can take weeks to clear up, but it will work. If the problem is from a dirty tank, change the filter and perform a 20 percent water change; then add a water clarifier containing aluminum chlorohydrate and polyelectrolytes to help clear the water.

Unclouding the Tank

The best advice for unclouding a goldfish tank is to make sure the filter is clean and allow it to run. This is especially true if you have just sent up your tank as it is normal for the water to cloud after a few days. It will stabilize itself. Water clarifiers bind particles floating in the water, allowing them to fall to the bottom or get caught up in the filter. Microscopic particles of uneaten food is fodder for bacteria, which causes cloudiness. Water clarifiers help remove the food and waste products and keep bacteria at bay.

Water Changes

It is essential you perform 20 percent water changes on a regular basis. How often this needs to be done depends on the size of your tank, the number of fish you have and whether or not you have a decent filtration system. If the tank is cloudy due to overstocking or overfeeding, perform a 20 percent water change every day until it clears up. Doing so will remove the nutrition the bacteria relies on and it will soon die off. Do not change more than 20 percent, no matter how impatient you feel. Doing so will stress out the fish.

Tank Additives and Best Practices

If your tank continues to become cloudy, try adding some aquarium salt (see label for dosing directions), water conditioners or an anti-algae product on a regular basis. Be careful not to overfeed your fish; remove any uneaten food after 10 minutes. Keep your tank out of the sun and perform routine water changes. With regular maintenance and vigilance, you should be able to enjoy your goldfish tank without the hassle of dealing with cloudy water.

the nest