Skip to main content

How to clear cloudy aquarium water in a few easy steps and make your fish happy

When your aquarium water is cloudy, you'll have to do some sleuthing to find the cause

Fish tank with healthy bubbles coming out of filter
Ja Crispy / Shutterstock

No matter how talented an aquarist or fish parent you are, you’ll probably run into cloudy aquarium water at some point. Maybe your filter breaks unexpectedly or one of your fish has tummy problems, and you wind up with a tank so murky you can’t see through it.

If you walk in to feed your fish and stumble on cloudy aquarium water, don’t panic. While a good tank cleaning will probably be necessary, it’s even more important to discover the underlying problem. We’re here to show you how to clear cloudy aquarium water and keep your fish safe from filth.

Cloudy aquarium with fish
Maverick Ace/Shutterstock

What does the color of my aquarium water tell me?

The first step: Figure out what’s wrong with your water, which means determining what color it is. This will give you more information than you think, as the shade will often hint at the deeper cause. You don’t need to hold up a paint-matching card or anything, but see if you can identify the hue. Would you describe it as more white, green, or brown? Each of these discolorations stems from something different and indicates a separate issue. Then tackle the problem by getting to the source.

Mother and son looking at aquarium
Westend61/Getty Images

Why is my fish tank water cloudy white?

Surprisingly enough, white aquarium water often means to leave it alone. Yup, this tint sometimes tells you that your tank needs to stabilize. In fact, too many water changes can actually spark cloudy water, which is frequently the result of a bacteria bloom. The good news is that as the tank cycles through, the bacteria and other dissolved nutrients will find a balance and the cloudiness will clear.

Recommended Videos

However, white water sometimes comes from other issues. To find out, test your tank and see if the chemicals and nutrients are out of whack. In that case, a conditioner can straighten out the problem. The one exception: If you recently put in new gravel and the water gets cloudy instantly, you didn’t rinse the stones enough. You’ll probably have to pull everything out and give it a good cleaning before returning it — and, of course, change the water again.

Hand cleaning tank with sponge
Sergiy Akhundov/Shutterstock

Where did all the green come from in my fish aquarium?

This one’s usually pretty easy to figure out. Most of the time, when your aquarium water is green, you’ll see an abundance of algae. Unfortunately, the tricky part isn’t getting it off but keeping it from coming back. When your algae is blooming, it means something else in your fish’s home is not quite right.

First, try adjusting the lighting. Like all plants, algae lives on sunlight, and your tank lamp or natural sunlight exposure could be encouraging the green water. You also need to run your full testing kit right away, since algae growth could indicate that your nitrate or other levels have gotten off. If your tests consistently come back out of range, make sure your tank is clean enough and that you’ve removed any dead plants or animals.

Hand holding a pH testing kit next to an aquarium
M-Production/Shutterstock

What does yellow water mean for the fish in my tank?

Yellow water gives the easiest diagnosis: Your tank is dirty. If your water looks yellowish or brownish, your filter is probably not up to snuff. First, do a thorough clean of the tank, including removing items like gravel and accessories for a scrubbing. Then, take apart the filter and examine it carefully. Some models have replaceable pieces that easily swap in and out.

Otherwise, you may need to invest in a new one — and don’t forget that adding fish might mean you need a more powerful system. Keep in mind, too, that no amount of filtration will make up for an overcrowded tank. Think about an upgrade to make more space, especially if your fish have grown or recently had babies who now have precious little room to swim.

Girl adds food into her aquarium
Dora Zett/Shutterstock

Why is my aquarium cloudy and won’t clear?

No matter the color (or the underlying conditions), you will almost always want to do three things to clear up your water:

  • Run a water test
  • Check your filtration system
  • Do a partial water change or maintenance clean

If you’ve gone through these steps and nothing seems to work, you’ll have to dig into your tank issues a little deeper. First, take a look at your own behaviors, especially how much food you provide during meals. You shouldn’t see any extra flakes floating around long after your fish have finished their meal. Next, pay even more attention to your swimmers and their habits, including the bathroom ones. Last, reach out to an expert, either by calling up your local store or posting pics to a forum.

Diagnosing your aquarium issue isn’t rocket science. With a few glances at the dirty aquarium and a couple of testing kits, you’ll get it back to beautiful clear water in no time. Bear in mind, many tank problems are invisible and don’t affect water color or clarity, so check your pH and nutrient levels frequently, even if everything looks good to the naked eye. Aquarium health means fish health, and keeping their home tidy will go a long way toward keeping them happy.

Rebekkah Adams
Rebekkah’s been a writer and editor for more than 10 years, both in print and digital. In addition to writing about pets…
Don’t kill your fish: How to prepare your aquarium before vacation
Aquarium in house with plants and controls

So you got a fish because they can be left alone for a few days, but now the time comes for your vacation and you aren't sure what to do. Do they need a fish sitter? Should you get a fancy monitoring system that connects to your phone? What's the best way to keep your mini ecosystem running smoothly on its own? The good news is, you absolutely can leave your fish when you go out of town, and it doesn't need to be too difficult - or too expensive. With a little preparation, you'll keep all of your swimmers happy and yourself stress-free.

How long can my fish thrive while I am away?
OK, first if you leave for just a couple days, as in anything less than 72 hours, you won't need to do much at all. You shouldn't have to perform water changes that frequently for most tanks and you can easily set up an automatic feeding system to ensure they get their meals on schedule. Set up a feeder before you go (and don't forget to test it while you're around to make adjustments). Additionally, in case of emergency, most fish can skip a meal and recover easily, though you should not plan for that. For longer trips or for fish tank care with special requirements, such as eating live prey, you'll need to move to the next best option: a sitter.
Do I need a pet sitter for my fish?
Lots of aquarists opt for a sitter when gone for more than a couple days. This brings a few benefits, including the ability to check on the tank and step in if something goes wrong. A friend or neighbor can also do spot cleaning and feed more difficult fish. You do need to ensure that whoever winds up taking care of your fish knows how to do so. The last thing you want is to hire someone who overfeeds the animals or clogs the filter - both of which can be deadly to your aquarium inhabitants.
How should I prepare my fish for my vacation?
First, schedule a partial water change for a day or so before you depart. This way you don't need anyone else to do it and you can rest assured that your housing will stay reasonably clean with the proper filtration. Speaking of which, check every part to confirm that nothing needs changing or replacing and that you've removed all the detritus. Use conditioners as necessary and perform a water check right before you go. If you only go for a short while or if you have an experienced sitter entering your home daily, that's really all you need to do. But if you don't have a human in place, you can instead rely on digital communications to protect your underwater life.

Read more
This is why your saltwater aquarium needs live rock in it
Saltwater aquarium with live rock.

Ask any saltwater aquarium enthusiast what they love about the hobby and their eyes light up as they describe the amazing colors and shapes of their saltwater fish. Many also express pride in successfully creating a closed and balanced ecosystem inside their home where fish and plants can thrive. One of the best ways to do this is to include live rock in a saltwater aquarium, according to experts at ARC Reef, a state- and federally-licensed facility that promotes sustainable aquaculture.
What exactly is live rock?
Live rock is the name given to rock and reef structures that act as hosts to marine organisms living on or within the rock. According to marine life experts at ARC Reef, live rock is usually comprised of calcium carbonate but it can be made of many different materials including synthetic substances, concrete, and dead corals. It serves as the foundation for natural coral reefs in the ocean and makes a wonderful foundation for home aquariums, according to ARC Reef experts.

What does live rock do for a saltwater aquarium?
The microorganisms on live rock, including hundreds of species of bacteria and plankton, feed on algae and fish waste which helps maintain a natural healthy environment inside the aquarium. Beneficial bacteria, sea urchins, snails, sponges, and purple coralline algae are just a sampling of the life you might find on quality live rock, say experts at ARC Reef. These could be visible on the rock at the time of purchase or might emerge over weeks or months after placing the rock in your aquarium.

Read more
These 3 fantastic fish make the perfect tank mates for your goldfish
Goldfish in aquarium.

Watching a community of fish peacefully swimming inside a colorful aquarium isn’t just interesting and fun, it’s also good for your health. A study published in the Environment and Behavior journal found that viewing aquariums led to noticeable reductions in blood pressure and heart rate. It also revealed that the more fish in the tank, the longer people watched, and the better their moods.

While aquarium hobbyists can choose from a huge variety of fish, the humble goldfish remains one of the most beloved. Many hobbyists start out keeping goldfish and eventually look to add other varieties of fish to the tank. Read on to learn about three fantastic fish that make great tank mates for goldfish.

Read more