The Fish Keeping & Aquarium Guide.

Best Phosphate Remover For Freshwater Aquarium

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What Is Phosphorous?

It is an organic element present in all living or organic matter, including underwater animals and your fish food. When these animals, plants, and other organic beings die and decay, phosphorous turns to compounds called phosphates.

Best Phosphate Remover For Freshwater Aquarium

Phosphates might disturb your water quality and thereby your fish health. It is why you want to reduce their levels in your aquarium.

The best and the easiest way to get rid of phosphates is to change the water. That said, there are now modern technologies that aid your phosphate removing process quickly and safely without needing to change the water.

These products are effective, easy to use, and improve your water health.

1) Seachem PhosGuard

Phosguard by Seachem is a product that effectively removes phosphates and silicates from both freshwater and saltwater.

It comes in the shape of tiny spherical pellets, thus having the ideal hydrodynamics and high surface area with increased porosity to absorb phosphates from aquarium water.

For the best results, you should rinse the product before first use and let your tank water flow through the product. For best results, you should place them in a way as to increase the water flow through the pellets. Take care to see the product itself does not roll and tumble as you let water flow through it.

You could use a filter-bag to place PhosGuard in it for easier maintenance. You can then place the PhosGuard where the water flows. Seachem PhosGuard works by employing fast-acting alumina oxide to absorb phosphates from the water. Since alumina oxide is fast-acting, it is sufficient to use the material inside a media bag or canister filter, or box filter.

The product works like a one-way-absorbing medium, unlike an exchange resin. It does not release anything into the water and thus is an excellent filter that causes no contamination. No phosphates or silicates are releases into the water.

It is easy to remove, dry, reuse until it is permanently exhausted.
The recommended dosage of PhosGuard is 85 mL (1/3 cup) for every 400 L (100 US gallons) of freshwater.

Keep in mind that although it is necessary to filter phosphates, a rapid drop in phosphate level is stressful to invertebrates in your water. It would be best if you, therefore, were careful not to overdose PhosGuard.

For the same reason, it should not be used in phosphate buffered freshwater since PhosGuard would remove the buffer of the water until it saturates.


  • The filter media is durable and effective against phosphates.
  • It is suitable for both freshwater and saltwater aquariums.
  • The spherical shape is ideal for absorption.
  • It can use until exhausted without any additional steps.
  • It can use in many types of filters.


  • It is expensive as compared to other products.

2) Fluval ClearMax Phosphate Remover

Fluval ClearMax is a resin that filters chemical compounds in water that support the growth of phosphates, nitrates, and nitrites. It removes algae in aquariums and prevents algae’s recurrence because removing phosphates means no possibility for algae to grow and thrive.

It also reduces terrible odors in stagnant water, makes maintenance more manageable, and keeps the water healthy for fish.

Fluval Clearmax comes with three media bags of 100g each. It is simple to use, just placed in the filter. The resin will then absorb all the unwanted compounds from water as it flows through the filter and keep the aquarium clean and free to breathe for your underwater life.

One such filter is sufficient for up to 27 gallons of water in both freshwater and saltwater conditions.


  • You can use it in the filter and the tank directly.
  • The material comes in media bags, easy to handle.
  • Absorbs without releasing residues into the water.
  • Absorbs phosphate and nitrate from water, which is its prime goal, very effectively.
  • It improves the health of the fish and the cleanliness of the water.


  • It can cater to only 27 gallons of water per filter.

3) D-D Rowahos Phosphate Remover

The D-D Rowahos Phosphate Remover is suitable to use as a filter media. It makes it extremely easy to use. You only insert it into the filter, where also the media goes.

Alternatively, it is possible to use a media bag in the filter, but the ideal way would be to use the material by inserting it into a media reactor. It might cause additional costs, but it is worth the added efficiency.

RowaPhos is one of the best phosphate absorption materials in the world and does nothing to your water. It does not leach back or contaminate water in any way while filtering for phosphates. For this reason, you don’t have to remove it after the media is exhausted immediately. It will still be inside the water without causing harm.

The product is easy to use and effectively removes both silicates and phosphates under both fresh and saltwater conditions.

Other such components deliver 30-40% phosphate removal efficiency by their weight, but RowaPhos far surpasses these numbers. It remains effective also in lower concentrations and has a high holding capacity.


  • Very efficient cleaner.
  • Easy to use.
  • It does not leach back into the water.
  • Suitable to both freshwater and saltwater.
  • Cons
  • It requires a media reactor to perform at its best efficiency.


  • It requires a media reactor to perform at its best efficiency.

Buyer’s Guide: Why Should You Remove Phosphate?

It is natural to find some phosphate levels due to organic matter decomposition processes in the water. These might be fish excrement, old food, or even plant particles. Depending on the aquarium environment, phosphate may or may not be as dangerous. For example, in standard freshwater aquariums, phosphate is not harmful, even in large concentrations.

Without adequate maintenance, when phosphate levels rise exponentially, algae proliferates and spreads fast. Such overgrowth of algae bloom can cause the tank’s oxygen levels to deplete and harm your underwater plants and fish.

To put it simply, your fish needs plenty of oxygen. With many algae around, they will not get adequate amounts of it and will not breathe. For this reason, it is essential to keep phosphate levels in the water in check.

A phosphate level of 0.5 ppm (parts per million) is a decent level of phosphate. Beyond this, it is harmful to the water-life.

When it comes to algae, phosphate is one of the essential elements necessary for survival. However, in almost all aquariums, algae is an undesired plant, best when kept to a minimum. For this reason, it is essential to cut off phosphate levels to a minimum.

How Does Water Acquire Phosphate?

Even tap water is a potential source of phosphate. It might get its phosphate from earth minerals from underground, which is the water source. It is also possible that water treatment processes add phosphate to water to prevent the rusting of infrastructures such as pipes and containers.

To check if your tap water contains phosphate, you can use a water conditioner to test a sample tap water.

Another possible source of phosphate is grocery store fish food. If you feed this to your fish, it might contain additional phosphates added as preservatives.

Overfeeding also causes phosphate overdosing in water because decaying food is a known source of phosphates in nature, produced when organic components break down.

Carbon filters might also cause high levels of phosphate in water because they release these components. However, many manufacturers have designed modern filters to prevent phosphate leakage into the water, so your filter might not be doing this.

To sum up, the following are possible sources of phosphates in water:

  • Dead and decaying of plant and algae.
  • Dead and decaying of animals, like fish.
  • Uneaten fish food.
  • Fish faeces.
  • Carbon filter media, if not designed to prevent phosphate leakage.
  • Tap water.
  • pH and kH buffers in the water.
  • Salts in saltwater tanks.

How To Maintain Low Levels Of Phosphate In Water?

After having filtered for the proper phosphate levels in the water, it is your job to maintain the tank such that phosphate levels remain low. Here is how to do it :

  1. Ration the amount of food: Since decaying food is a significant component in phosphate production, cut back on the amount of food and how often you feed the fish. Most adult fish survive on a pinch of food a day, which is not much. Make sure to clean the tank of any food that the fish refused.
  1. From food source: Since phosphate is a preservative, it is present in store-bought fish food. It helps to choose brands of fish food that have lower phosphate levels.
  1. Water Source: In many cases, tap water already has a phosphate level of 1 ppm. If this level is high, get an alternate water source for your aquarium. Treat tap water before using it.
  1. Change water frequently and regularly. Change about 10-15% of the tank water every week. That way, you will reduce the phosphate levels by discarding water saturated with unwanted compounds.
  1. Keep your tank clean: Clean your tank and rid the walls of any debris and algae of avoiding phosphate build-up. Vacuum the floor for uneaten fish food and other organic decay material.
  1. Choose the correct filter media: Make sure that your carbon filter is treated or that you have a carbon filter designed not to release phosphates into your fish tank.
  1. Avoid water treatment unless necessary: Unless you must, do not treat water. For example, when you add buffers to alter pH, change hardness, or condition the water, the compounds added contain phosphates. Be careful while choosing your water products and select the ones with the least amount of phosphate.


To conclude, it is not possible to completely rid your water of phosphates. It is because organic phosphates will convert to soluble orthophosphate. Once dissolved, separating phosphate components from water is very difficult.

However, with a diligent maintenance schedule, you can keep your organic phosphate levels in check and keep the water of your fish tank healthy.

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