Biopellets For Aquarium: How They Work and How To Use Them

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Dr. Mollie Newton
Published by Dr. Mollie Newton PHD| Senior Editor
Last updated: April 11, 2024
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Whether you’re beginning the cycling process for your tank, or have been grappling with ammonia-related problems for a while, biopellets may prove to be the answer to your difficulties. Through a mix of practical testing, study, and experimentation, we’ve crafted the perfect guide for you. Keep reading to see our evaluation of the best products, and to comprehend how integrating biopellets into your routine could be advantageous.

Article Summary

  • Biopellets are a natural carbon dosing approach used by aquarists to help lower nitrates and phosphorus, limit algal growth, and promote the growth of beneficial denitrifying bacteria, resulting in a faster nitrogen cycle.
  • They can be used in both freshwater and saltwater tanks, but adjustments to lighting and water quality monitoring may be necessary.
  • The use of biopellets may require increased coral feeding, and water flow should be carefully controlled in a bio reactor.

What are biopellets?

What do biopellets look like
What do biopellets look like

A natural carbon dosing approach used by aquarists to help lower nitrates and phosphorus and limit algal growth. They are packed food for beneficial de-nitrifying bacteria. Thus, they encourage colony growth leading to a faster nitrogen cycle.

Are biopellets worth it?

If you have a high bioload (many fish in your aquarium) or a skimmer where much protein-rich matter is sitting for a long time we recommend biopellets as a way to better maintain your tank and assist in nitrate reduction.

What are biopellets used for?

When added, biopellets act as a nutritional source for denitrifying bacteria. The addition is necessary because aquariums are considered closed systems, in other words the only food available is the type that is already present.

Oftentimes nitrogen and phosphorus are easily available through fish excrement but carbons are a limiting factor in colony growth. The addition of biopellets eliminates this limiting factor and allows more development.

Do bio pellets work?

Not only do they work to reduce nitrate, prevent algae blooms, and increase your skimmer capabilities they also produce clearer water and increase the overall health of your aquarium.


Part of an excellent filtration system is having a good pump.

What do biopellets remove?

They don’t remove anything per se, rather they provide nutrition for denitrifying bacteria to grow.

Do biopellets remove nitrates?

No, biopellets contain a large amount of carbon, a limiting factor in beneficial bacteria cultivation. The addition of biopellets encourages development, which then removes nitrates by transforming it into nitrites, a usable form of nitrogen for your fish and plants.

How long does it take for biopellets to work?

Following the addition, you should see consistent conditions changes in 4-8 weeks. This time is spent establishing a bacteria column.

Bacteria grows quickly so you should add 25% of the recommended amount to your reactor or else you run the risk of your colony overpopulating. If your bacterial colony grows too large there will not be enough nitrogen and phosphorus in the tank to support it.

Biopellets vs GFO’s

GFO Reactor
Granulated Ferric Oxide

Granulated ferric oxide (GFO’s) are another common solution to adjusting your water parameters and are similar in equipment requirements (a reactor is needed). Where biopellets decrease nitrates the addition of GFO decreases phosphates.

Using a GFO reactor is more common in a reef tank where high phosphates are a common issue. However, the dust can be toxic to fish which is why it is important to have a good reactor.

How to use biopellets

You should first read the instructions of your suggested brand. Measure the amount instructed (25% if it’s your first time using them in a tank), and insert them into a media reactor. The reactor should then be installed into the pump and the flow adjusted.

The water flow output should be enough that the pellets are tumbling moderately fast. This prevents biofilm from forming and increases the amount of time between media changes. After installation, you have the option of adding a dose of beneficial bacteria. If you’re cycling a tank we recommend this method to speed up the cycling process.

Leave the biopellets in your tank and allow them to slowly degrade over time. In 6-12 months you can add additional products to the reactor.


Never remove biopellets from your tank, once they have grown a bacterial colony on them, removing them could crash your biological system.

Things to consider: Biopellets benefits in the reef tank

While biopellets can be added to freshwater and saltwater tanks, there are some specific things to consider when adding them to a reef tank.

Should I use a protein skimmer?

If you use a protein skimmer the addition of biopellets could lead to increased skimmer performance. To effectively incorporate this one-two system add the reactor right before your skimmer, this will allow biofilm, algae, or dead bacteria distributed by the output to be stopped before the general tank. However, you shouldn’t add full pellets to your skimmer as the flow will likely not be high enough.

How much bacteria should I add?

Even after your aquarium is fully cycled you should continue to dose with bacteria. This will help replenish colonies that have begun to die and add diversity to your tank. The amount you use depends on tank size.

How do biopellets affect tank lighting?

After a few weeks, you will begin to see clearer water. While this is a good thing you might need to lower your lighting to control algal blooms. Additionally, you should reduce the light as your corals will not be able to adjust to the increased light penetration quickly.

Why is alkalinity important?

Be sure to consistently monitor your water quality. The addition of biopellets can potentially cause a lowering of aquarium pH (making it less alkaline or acidic) due to the increase of CO2. Since alkalinity is easy to dose using soda ash we recommend fixing this first and seeing if it remedies the low pH.


If you start to notice your corals have burnt tips it’s a sign that there’s low alkalinity.

GFO & GAC what do they mean?

Granulated Activated Charcoal
Granulated Activated Charcoal

You probably will not need to continue adding granular ferric oxide or granulated activated charcoal because pellets will prevent water from becoming discolored themselves.

Should I feed my corals more?

You will likely need to increase how much you feed your corals, this is because the bacteria that grows on the surface of the pellet is so efficient it will start eating your coral food.

How high should my water flow be?

Your pellets should be housed in a bio reactor that is specifically rated for a certain gallons-per-hour. If this flow is obstructed the water could become toxic for your aquarium. The reactor is necessary equipment when it comes to biopellets.

How many biopellets for aquariums?

You should add a dose of 200mL of biopellets per 50 gallons of water. If it is your first time add 50mL per 50 gallons of water or 25% of the recommended amount.

Biopellet Suggestions

Our top three products were chosen for their effectiveness, ease of installment into your reactor, and price point. Regardless of what you decide they will all help increase the health of your tank.

Kolar Labs Metabolix Biopellets

A trusted name in aquarium chemicals, kolar labs has an all natural product made from corn that comes in a wide range of sizes.

Kolar Labs Metabolix Biopellets

This product can be combined with others in the kolar lab family or with outside products. With excellent quality control on materials and detailed instructions these are an excellent purchase for your fresh or saltwater tank.

TL Reefs Premium

If you’re looking to get the most bang for your buck this product is for you.

TL Reefs Premium

An all natural solution for nitrate control in your tank.

Continuum Aquatics Reef Bio Pellet Fuel

The use of biopolymers gives this product its strength, and requires a smaller dose than other products.

Continuum Aquatics Reef Bio Pellet Fuel

Not only is this product strong, but it also boasts a timed release ensuring that your bacteria will have the best success possible.


In conclusion, the addition of biopellets can be beneficial to the overall health of your tank, keep nitrate levels in check and lead to less overall maintenance on your part.

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