Why is my Aquarium Cloudy? Why is my Aquarium Green?

Is your Aquarium cloudy or green and you don’t know why? Well we are here to try and help you with that. It isn’t uncommon for an Aquarium to be clear one day and the next for the water to look cloudy, milky, and possibly even green. Most of the time these issues are not major and can be solved with a little time and effort. Sometimes it may take a little more drastic measures such as moving the tank to correct the issues.

We’ll start with one of the most common issues – Green Water. This one is usually a pretty simple issue, too much light, nutrients or both. Green water is essentially just water full of algae. The algae needs two things to really thrive – light and food. The food is almost always going to be present unless you are diligent with weekly water changes and keep your nitrates very low. If you do not keep up with water changes the nitrate level in your tank (which is basically the end result of fish poop, leftover food, decomposing plant matter etc) will rise and Algae will feed on it. The other thing Algae needs is light, many fish tanks are placed near windows and this is a perfect recipe for an Algae storm. If possible keep the shades closed and it may solve the issue, otherwise moving the tank may be required. Too much direct sunlight will almost always grow Algae and cause some unpleasant greenery in the tank. If you have live plants in the tank it is possible for them to use up all the nutrients and thus the Algae will not thrive, however a proper planted tank is also a lot of work. So it may be easier to simply limit the amount of light. You will also have issues if you have old bulbs, as they tend to accelerate bad algae growth. You want to replace bulbs yearly as well as keep them on a timer for 8-10 hours a day maximum, anymore than that and it will also promote algae growth. If you have live plants, then you can keep lights on for up to 12 hours but for tanks with no live plants I like to limit the amount of light to give Algae less of a chance to take over.

If you have cloudy water or milky white water then it’s likely a different issue. You’re probably seeing a bacterial bloom and there is no quick fix for that really. Your tank is most likely in the cycling process and will need to settle on its own. It is most likely having a cycle because it is a new tank, this is perfectly normal. If you just added new substrate, gravel, sand, or anything similar you’ll almost always have cloudy water as well. This is perfectly normal and will usually clear up in 24-72 hours as all the fine particulates settle to the bottom. If you cleaned all of your filters recently and then it got cloudy you’ve killed off to much beneficial bacteria and the tank has re-started the nitrogen cycle. If you have fish in the tank this can be dangerous for them as the Ammonia will spike during this time because there is not enough beneficial bacteria to turn it into less harmful Nitrates. You can treat the tank with Ammonia neutralizers such as SeaChem Prime or AmmoLock or AmQuel. This will help keep the fish safe while the tank goes through its Ammonia cycle and gets back to normal. The water will be a bit cloudy during this time but it will clear up.

If you had to treat your tank with medicine of some sort for a sick fish this can also kill off beneficial bacteria causing the tank to cycle again. This is why owning a quarantine/hospital tank is suggested. It eliminates the need to treat your main tank and risk all of its inhabitants safety. You can place the sick fish into its own tank that is smaller and treat only them, you also won’t need as much medicine as you would to treat your larger display tank.

Water changes will also help in any of the above issues and are encouraged. It will not only help the water clear up faster but it will help keep the fish safe by removing the Ammonia. It will also re-oxygenate the tank as well which will help if the oxygen levels of the water are low and keep your fish happy and healthy.

If you have brownish or yellow water it can usually be fixed by simply adding activated carbon to your filters temporarily. This is often caused by driftwood leeching tannins into the water. I myself like the slightly tanned water caused by real driftwood, it is much more natural to the fish as well. However if you want that crystal clear water like the Saltwater tank pictured below you’ll either need to remove the wood or add some carbon to your filters which will remove the tannins and turn your tank into a crystal clear oasis.

If you’re still having issues after trying to above solutions feel free to ask in the comment section below and we’ll do our best to help.

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