How To Get Crystal Clear Aquarium Water

An aquarium always looks best when the water is 100% crystal clear. But achieving this can be elusive, especially if you are a novice aquarist. Imbalances in the water chemistry, algal or bacterial blooms, dissolved organic carbon, and inorganic particulates can all reduce water clarity. 

How to get crystal clear aquarium water, and maintaining it, requires a few different approaches. Keep reading for details on those factors and learn what you need to do to keep your tank sparkling clean!

Why Is My Aquarium Not Crystal Clear?

Cloudy or discolored aquarium water is almost always due to an imbalance in the tank’s water chemistry. A crystal-clear aquarium means that all the bacteria, algae, micronutrients, and carbon are perfectly in balance.

If your aquarium filter is not powerful enough, you do not clean the filters often enough, or you over-feed the fish, waste levels in the water get too high. Excessive amounts of ammonia, phosphates, and nitrates lead to bacterial and algal blooms in the tank. 

Green aquarium water means that there has been an algal bloom. Green water will not harm the fish, but it makes an aquarium look awful. 

If the water looks cloudy and grey, it indicates a bacterial bloom. This is not dangerous for the fish, and the water should clear up on its own over time. However, if the water remains hazy, it indicates a more serious issue. 

Tea-colored aquarium water is due to higher levels of dissolved organic carbon or tannins. Again, this is not harmful to the fish, but it may not be the desired aesthetic for your tank. 

If the water looks cloudy with a grey or brown color, the problem is often due to inorganic particulates in the water, like clay. It can also be caused by high levels of phosphates, silicates, or iron. 

How To Maintain Crystal Clear Water In An Aquarium

The key to keeping aquarium water crystal clear lies in how well you maintain your fish tank. Neglecting regular maintenance practices is sure to cause cloudy, discolored water. 

To keep aquarium water nice and clear, you must do the following:

  • Clean the tank once a week or, ideally, bi-weekly. 
  • Do frequent water changes. 
  • Equip the tank with a good filtration system that is powerful enough for the size of the tank. 
  • Avoid over-feeding your fish.
  • Test the water regularly.
  • Prevent nitrate and phosphate levels from getting too high.
  • Keep lots of healthy aquarium plants.
  • Add snails and shrimp to the tank to eat excess algae and organic waste. 
  • Use a fast-acting water treatment.
  • Use a chemical flocculant or clarifying treatment. 

The Issue Of Murky Water In A New Aquarium

When you start a new fish tank, it is normal for the clarity of the water to change in the first few days. The water may look clear on day one, but by day five, it is cloudy and grey. 

It is totally normal for the water in a new aquarium to get cloudy. In a brand-new tank, there are no established groups of microorganisms to balance the mineral and nutrient levels in the water. 

It takes time for beneficial bacteria and microbes to colonize the tank. Once their populations in the filter media have grown enough, they start removing ammonia and nitrates from the aquarium water. 

The process of establishing beneficial nitrifying bacteria in a new tank is called cycling. It takes a month to two months for the cycling process to happen naturally. 

The best thing to do to clear up the water in a new aquarium is nothing! You just have to keep the aquarium filter, pump, and heater running as normal and wait for the water to clear up on its own. 

How To Get Crystal Clear Aquarium Water Naturally

There are commercial products you can add to aquarium water to make it clear, but before resorting to those methods, it’s better to try some natural ways to clear the water first. 

The best natural ways to get crystal clear aquarium water are:

  • Add lots of beneficial plants to the tank
  • Keep fish, snails, and shrimp that are algae eaters
  • Add activated carbon to the filter media.
How To Get Crystal Clear Aquarium Water

Aquatic Plants

How to get crystal clear aquarium water involves keeping lots of the right kinds of aquarium plants, as they’re beneficial for keeping the water chemistry stable. Many aquatic plants absorb ammonia and minerals like iron from the aquarium water. In this way, the plants help to prevent blooms of algae or bacteria. 

The most beneficial plants to have in an aquarium are Java moss, willow moss, Java fern, hornwort, Amazon sword, water wisteria, Sagittaria, ludwigia, rotala, anacharis, and anubias. 

Algae-Eating Organisms

Giving your aquarium its own clean-up crew is a great way to make tank maintenance easier and keep the water clear. There are loads of organisms that feed on algae and organic debris in a fish tank. 

The best algae-eating fish and freshwater organisms to add to a tank are bristle nose pleco, Siamese algae eater, Chinese algae eater, twig catfish, otocinclus catfish, platys, mollies, guppies, nerite snail, mystery snail, Malaysian trumpet snail, cherry shrimp, and Amano shrimp.

Activated Carbon

Activated carbon is excellent for removing toxins and waste substances from water. Adding activated charcoal to your aquarium filter is a good way to naturally boost water clarity. 

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Water Treatments For A Crystal Clear Aquarium

There are loads of products on the market for improving the clarity of aquarium water. Clarifiers, AKA flocculants, bind to microscopic bits of debris, algae, and bacteria in the water so that they can be filtered out. 

Clarifying agents work very quickly. Some will turn aquarium water crystal clear in just an hour! 

These treatments do not address the root cause of issues with water clarity. They are like a band-aid – they’ll conceal the issue in the short term, but the underlying problem remains. 

The best water clarifying treatments to use are:

  • Aqueon Water Clarifier – this product is incredibly fast-acting, and it is safe for fish. It will not help with major bacteria or algae blooms, but it will help to clear up slightly cloudy water.
  • Seachem Clarity – this product works in both freshwater and saltwater tanks. Note that there may be a waiting period before you see the full effects.
  • API Accu-Clear – it is safe for fish, shrimp, and snails, and it works quickly to clear up murky water. 

Best Aquarium Filter For Crystal Clear Water

A good filtration system is the most important thing for crystal clear aquarium water. There is no such thing as over-filtration when it comes to aquariums! 

For crystal clear water, you need three different types of filtration:

  • Mechanical filtration – physically traps and removes visible particles of dirt and debris from the water. 
  • Biological filtration – beneficial microorganisms and enzymes process waste and organic debris, removing it from the water. 
  • Chemical filtration – activated carbon removes odors and toxins from the water. 

You get aquarium filtration systems that incorporate all three of these types of filters. They are the best for water clarity. 

You also get UV aquarium filters. These use UV light to kill algae, bacteria, and other microorganisms. These UV filters are a bit pricier, but they are well worthwhile as they are excellent for water clarity. 

Aquarium Maintenance For Crystal Clear Water

Keeping the water in your fish tank crystal clear takes work. Incorporate all the following in your aquarium cleaning schedule for perfect water clarity:

  • Vacuum the tank substrate weekly to prevent the build-up of physical waste.
  • Do small water changes frequently to stabilize the water pH and reduce nitrate levels.
  • Clean the sponges and filter media in the aquarium filter regularly to keep the filtration system working properly.


There are several options for how to get crystal clear aquarium water. You may want to try water treatment products, or natural solutions such as plants and certain organisms that eat algae. Investing in, and maintaining, great filtration is also advised.

Scheduling regular cleaning of your tank, water and equipment will also help you achieve a crystal clear aquarium.

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