How To Clear Cloudy Water In Your Fish Tank

By: Chewy EditorialPublished:

How To Clear Cloudy Water In Your Fish Tank

You’ve always wanted an aquarium. You see those shows on TV where they set up a huge, beautiful tank in under an hour and think, “It’s gotta be easy, right?” So you head off to the local pet store, buy a tank setup and head home. (If you go to a good store, they won’t sell you fish, just the tank and all you need to go in it.) When you get home, you follow all the instructions that the shop clerk gave you and set up your first aquarium. Everything looks perfect, like the beautiful tanks you see on TV, and you can’t wait to add fish. You get your fish and after you carefully follow the shop clerk’s directions to float the bag and add some water to “acclimate” your new charges, you add them to the tank. You dump some food in and admire your handiwork. All is good. Or so you think.

The tank looks great the next day when you feed the fish in the morning. You head off to work or school and look forward to coming home to your beautiful, new aquarium. You’ve heard horror stories from some folks about how hard aquarium keeping can be, but yours looks beautiful so they must have done something wrong. Obviously, you’ve got a wet thumb! That evening, you return home and notice a bit of gray cloudiness in the water. Maybe it’s just your imagination. You feed the fish, turn out the light and go to bed.

The next morning, there’s no mistaking it. The water looks like a gray rain cloud has descended into your tank. You call the shop. They may tell you about something called “new tank syndrome.” Or they may try to sell you a bunch of things to fix the problem. The quick fix seems to be the way to go. You buy this and that potion and add them to the tank. It may even clear up for a day or two, but then the cloudiness comes back with a vengeance. You go to an online forum or chat-room. Someone suggests a water change. So you perform a water change. You clean out the filter, just in case. Things seem to get better, and then get worse again.

Ah, now you see why so many folks just chuck it all and sell the tank at a garage sale. But not you; no, you want to figure it out. What the heck is going on? What is this cloud and where does it come from?

Cloudy Aquarium Water

Cloudy water is probably the single biggest complaint of new aquarium owners. It seems to mysteriously appear and mysteriously disappear almost overnight. Usually the water takes on a grayish to whitish coloration. Most often, it is just a thin haze, but in really bad cases it can get so thick that you can’t see the background. Usually, it appears on the second or third day after setting up a new tank, and it disappears all on its own in a week or so. Sometimes, we play around with things and prolong the cloudiness, extending it for weeks or more. It seems like the more we play around with the tank, the longer it hangs around.

The cloudiness is actually a bloom of microscopic life: bacteria, protozoans (single-celled animals) and micrometazoans (microscopic multicelluar animals). It is basically the same thing that fish breeders call infusoria. They cultivate infusoria as food for newborn fry. It’s great food for newborn fish, but not for a display aquarium! The color and extent of the bloom varies from tank to tank, because the exact composition of microscopic critters is unique to each tank (even two tanks sitting next to each other) depending on which critters were added, what food is available, what microscopic predators arethere, etc. When you add water to your tank, you add a chlorine remover. Chlorine is added by the water company to kill any microscopic life in the water, but now you’ve removed it and these diminutive life-forms can start growing again. You add fish, which come with some microscopic life in their water to give this new microscopic community a kick start.

In addition, you start adding fish food, which the fish eat. That then becomes waste, which also goes into the water. There is always uneaten food, too. The microscopic life now has a food source and begins to multiply. At this point there is little to consume this microscopic life or to compete with it, so it just goes on a population growth spurt and fills the tank. Slowly over the next couple of weeks, the filter bacteria become established and begin to break down the waste products, eliminating the food source for the microscopic critters. As this happens, the free-floating microscopic life reaches critical mass and collapses. Some microscopic critters will remain, but unless something goes out of balance (say a fish dies unnoticed or you feed too much), they will remain at healthy, limited levels in the tank.

Treat and Avoid Cloudy Aquarium Water

So let’s explore how to clear cloudy water in your fish tank. First off, it may seem counterintuitive, but the best way to treat that initial burst of cloudy water is to let it go. It looks worse than it is. If you let the natural cycle complete itself, the cloudiness will go away on its own in a few days to a week or so. As long as the fish aren’t gasping at the surface, they’ll be fine. Only feed a little bit, every other day, until the cloudiness is gone. Make sure the filter is running properly, but do not clean it unless it is not running properly. The best way to defeat cloudy water is to avoid it in the first place. Fortunately, this is actually easy. Five simple steps can avoid cloudy water, new tank syndrome, and all of the other maladies associated with poor water quality. Follow each step, and you’ll be a successful aquarist.

1. Be Patient

The most important thing is to be patient. You have to realize that an aquarium is a glass box full of living things, and no living thing is instant. Patience is sometimes difficult for us to achieve in this world where we can talk instantly to someone on the other side of the world, or call up a Web page in a billionth of a second. Fish, invertebrates and other aquatic life, including filter bacteria, require time to become adapted to their new home and begin to grow. If we try to rush the natural process of establishing a tank and immediately stuff a new tank full of life, things will go wrong. When something like a bloom of cloudy water happens, first try to figure out what happened, and then, once you figure out what went wrong, correct it. Don’t just start adding chemicals and cleaning things. That might set the establishment of your bacterial colony back and actually prolong the period of cloudy water. Be patient.

2. Seed With Good Bacteria

The next most important thing is to start off by seeding the tank with good bacteria to get the natural processes going. You can buy prepackaged bacterial cultures that are added to the tank. You can also buy gravel that is pre-seeded with bacteria and other life-forms to give the tank a kick-start. You can add live plants, which do double duty because they act as a natural filter of sorts and are covered with healthy microscopic life that will serve as a foundation for the tank’s microscopic community. You can add a handful or two of gravel from an established tank, a piece of rock or driftwood already covered with plants and microscopic life, or a filter pad from an established tank. Personally, I always keep a few extra sponge filters running in established tanks. That way when I want to set up a new tank, I just move one of these extra sponges to the new tank, and it is good to go. Some shops even sell pre-seeded filter pads or wheels that are ready to go.

3. Perform Regular Filter Maintenance

Maintaining the filter is probably the most overlooked aquarium task. Filters are designed to support your tank’s inhabitants, and many manufacturers rightly call the filter a “life support system.” Follow the manufacturer’s instructions on maintaining your filter. You can have the most expensive, high-end life support system for your tank, but if you don’t keep it clean and in working order, it will fail. Even an old-fashioned, inexpensive box filter that is regularly maintained is better than the latest high-tech filter gadget that gets ignored.

Set up a regular schedule and maintain your filter. The slightest slowing of flow should be investigated and addressed immediately. Failure to do so could mean cloudy water or, worse, death for your fish.

4. Do Regular Water Changes

This is usually the most intimidating task of all for new aquarists and is probably the second most overlooked maintenance task after cleaning the filter. Yet today changing the water can be the easiest of all maintenance tasks with a device that hooks up to the faucet. In the wild, fish are always getting water changes as new water flows in from upstream or is added due to rain. The best rule of thumb is to change as much as you can as often as you can. Some breeders change up to 90 percent every day. That’s a lot, but you get the idea. For a lightly stocked tank, 25 percent every week is fine. Some aquarists stretch it out to every other week, but that is pushing it. Water changes are the easiest way to maintain good water quality and can be done in a matter of minutes. Water change time is also a great time to get a close-up view of all of the aquarium’s inhabitants. Take advantage of water change time to poke into every nook and cranny of the tank to make sure everything is OK.

In my opinion, one of the greatest inventions ever in the aquarium hobby is the water-change device that hooks up to a water-powered pump at the faucet and allows you to drain water while vacuuming your gravel, then allows you to fill the tank back up with a simple flip of a switch on the pump. No hauling heavy buckets, no spills, no drips or mess. The Python No Spill Clean And Fill aquarium maintenance system is an excellent example. Now several other manufacturers make a similar device, including Aqueon and Lee’s.

The only things to watch out for are that you test the temperature of the new water you are adding so that it is close to your tank’s temperature and that you add an appropriate chlorine remover when doing this! Chlorine removers are instantaneous and no harm will come to your fish. Change as much water as you can — 20 to 25 percent once a week is a good rule of thumb. With one of these water-change devices, you can change half the water in a 55-gallon tank, while vacuuming the gravel, in less than half an hour.

5. Stock & Feed Lightly

Probably the things that kill more fish than any other mistakes a beginner makes are adding too many fish to a tank too quickly and feeding too heavily. All of the “rules” that I’ve ever seen for stocking an aquarium address how many fish one can cram into a tank. I’ve never seen a rule that says something like “only put a few fish in your tank.” Sit by a body of water in nature. You won’t see fish stacked on top of one another, and you won’t see all kinds of different fish in the same area. Don’t do that in your aquarium, either. A few groups of fish well planned out and tastefully added makes much more of an impact than a huge mishmash of fish all stressed out and piled on top of one another. They’ll live much longer and be much happier.

Realize that fish are not mammals. They do not need to eat two or three meals a day. Their bodies aren’t designed to handle that much food. Feed them lightly once a day, and give them one or two fast days a week. Many times in the wild fish will only eat a few times a week when they come across food. Many predatory fish only eat once or twice a week, or less.

Due to this scarcity of food in the wild, fish instinctively eat as much as they possibly can any time food is available. If we feed two or three times a day, every day, that is way more than their bodies can handle, and it leads to all sorts of health problems. Maintaining water quality is one of the most important and most misunderstood things with which a new aquarist has to contend. When you follow these five simple steps you will be able to sit back and enjoy your own relaxing, beautiful, underwater scene right in your own home.

Mike Hellweg is a master fish breeder, author and speaker. He is active in local and national hobby organizations and runs a fish hatchery.

Featured Image: LexyLovesArt/Thinkstock


By: Chewy EditorialPublished: