How to Clear Up a Cloudy Fish Tank
A cloudy aquarium can make it difficult to enjoy your fish tank. In this article, we explore the many reasons why your aquarium may look hazy and how to clear up the murkiness as quickly as possible.
You will first need to pour some tank water into an empty plastic cup or bucket. This will let you examine the water’s color and cloudiness without interfering.
1. Particles in the Water
The cloudiness in water is usually caused by excess food, fish waste, dirt substrate, and other miscellaneous materials. Small pieces of substrate can float in the water column when you set up a new aquarium or plant your plants. The powder usually settles or is collected by the filter within a few days. However, if the problem persists after a week you might need to make multiple large water changes or thoroughly clean the tank.
Rinse the substrate
until all the silt is washed away.
Setting a schedule for aquarium maintenance is a good idea if the aquarium hasn’t been cleaned in awhile. This will allow the water to remain clean and clear. It is highly recommended that you use an Aquarium Siphon to clean and change out the water. (Read this article for a step-by-step guide on how to use a gravel vacuum.)
Also, don’t forget to clean the filter once every month. The filter can be compared to a trashcan that collects garbage. It can no longer absorb particles from water if it becomes full. To remove the accumulated debris, squeeze the sponge filter or gently wash the filter media in old tank water. (Remember that after you clean your tank and filter, the water may remain cloudy for a couple of hours until the filter has a chance to re-gather the floating specks.)
The foods you feed could be the reason your aquarium has murky water. Messy fish foods (typically the kinds that contain very few binders) can turn into dusty fish poop that breaks apart very easily in the water. Instead, feed “cleaner”, foods such as frozen bloodworms or live foods. These will be gobbled up quickly, and then turn into more cohesive fish waste.
Keep eartheaters and other bottom feeders in your aquarium as they can stir up the substrate while searching for food on the floor. If they perpetually cause cloudiness in your aquarium, you may need to add more mechanical filtration to scrub the water. Any type of water filtration that strains out the debris, such as a coffee filter, is called mechanical filtration. Mechanical filtration is made possible by the use of sponge, undergravel, and hang-on back filters. You can add a prefilter sponge on the intake tube to protect it. The coarse sponge pads will catch larger particles. A fine poly pad will trap smaller particles. (Fine poly pads are not reusable and should be replaced when they become clogged with gunk.) Additionally, you can improve water circulation with power heads to eliminate any dead spots in the aquarium and make sure any loose particles get sucked up by the filter.
Finally, water clarifiers can be used for clearing up water that has become cloudy due to debris. They contain a special clay or chemical that bonds with suspended debris particles, causing them to clump together so that they get caught by the filter more easily or settle to the substrate. Water clarifiers stick to the particles to make them larger, so cloudiness can often look worse before the filter can collect all of it.
2. Bacterial bloom
If the tank water looks almost like diluted milk, and there are no visible particles in it, you might have a bacterial bloom. When there’s an excess of nutrients in the water and not enough beneficial bacteria to consume it all, the bacteria colony compensates by rapidly reproducing. This rapid population growth makes the water look like someone put a spoonful in the tank. (Read our guide to the aquarium nitrogen cycles for more information about beneficial bacteria.
When there isn’t enough beneficial bacteria in the aquarium, or when a large number of fish are added to it suddenly, bacterial blooms can occur. It can also occur when a large portion of the beneficial bacteria has been killed or removed. This could be caused by overcleaning of your tank water, changing too often or using medications that aren’t safe for beneficial bacteria.
Do nothing. Don’t add a UV sterilizer or do lots of water changes to remove the haziness; this just makes the bacterial bloom last even longer. Instead, wait for the water to clear up over the next one-two weeks as the bacteria starts to reestablish itself.
3. Green Water
Cloudy water can also be caused by bacteria. You may have an algae bloom if your tank water has a green tint or looks like it is full of peas soup. Green water is caused by tiny, free-floating algae and is actually very good for raising baby fish. It is a great food source for fry and prevents larger fish from preying on them. It can block light from reaching your plants and prevent you from looking into your aquarium.
Too much light combined with too many nutrients can cause green water. This is commonly caused by excess food, fish waste and fertilizers. Green water, like bacterial blooms can’t be removed with fine filter floss or huge water changes. To kill algae, it is recommended to do a large water switch, turn off the aquarium light, wrap a blanket around your tank for 7-10 days, then do another large water changes. Green water can survive without much light so make sure that your aquarium is completely darkened. You should be careful as your plants could suffer from this lack of light. Also, the dead algae can create an ammonia spike that harms the fish or causes another green water bloom from the excess nutrients.
We recommend that you get a UV sterilizer instead of the blackout method. Green water is easy to treat so you don’t have to buy a large one. The UV light actually alters the structure of the algae’s cells so it can’t reproduce. Once the algae has been sterilized you can perform multiple water changes to remove any remaining green water. Your water will soon be clear again.
4. Brown Water
When your tank water has a brown tinge instead of green or milky white, it’s often caused by tannins – an organic compound naturally found in catappa leaves, driftwood, and other botanical materials. While tannins can often be used to keep and raise certain species of fish in blackwater environments (e.g., to keep them alive), most people prefer to keep their aquariums filled with clear water.
If you aren’t adding more tannins to your water, manual water changes may be able to slowly remove brown water. The tannins can be removed faster if you have new driftwood. If these approaches still don’t work, try using chemical filtration – such as activated carbon in a filter bag, carbon pads, or Seachem Purigen – in a hang-on-back or canister filter. Activated Carbon can build up tannins and toxins over time, so it must be disposed. Purigen, however, can be reused and can be “refreshed” with bleach to remove any impurities.
5. Cloudy Aquarium Walls
The problem could be in the aquarium walls. Make sure the main viewing panels are clean by using an algae scraper to scrub the inside. Then, wipe the tank’s exterior with an aquarium-safe cleaner. Acrylic aquariums require a scraper that is safe for acrylic. Finally, the glare caused by lights around your aquarium can sometimes look like haziness, so try adding an aquarium background either on the inside or outside of the tank.
You aren’t sure how often to clean your fish tanks? Check out our free guide that teaches you what kind of water change schedule is right for your aquarium!