The Best Biopellet Reactor (2024 Buyer’s Guide)

A saltwater aquarium
Dr. Mollie Newton
Published by Dr. Mollie Newton PHD| Senior Editor
Last updated: May 14, 2024
Review Process and Evaluation Criteria
We conduct hands-on testing for all the products highlighted in our reviews and guides. Through anonymous product ordering and involving an independent team of testers, we gather direct experience to offer recommendations backed by data.

The best method to ensure safe levels of nitrates and phosphates in a saltwater tank is by utilizing a biopellet reactor alongside biopellets. The accumulation of these substances can result in significant issues in saltwater reef tanks – an issue you may or may not be aware of. However, what’s crucial is understanding that it can negatively impact your fish and corals.

When I initially started my saltwater tank journey over a decade ago, this was something I was unaware of, which led to my first reef aquarium being a complete disaster. Thankfully, I’ve learned a lot since then, and I now use biopellets in all my saltwater tanks. However, choosing the right biopellet reactor can be a bit confusing as you’ll need to consider things like the volume of your tank.

Article Summary

  • Biopellet reactors are used to maintain safe levels of phosphates and nitrates in saltwater tanks, which can be harmful to fish and corals if present in excess.
  • Recommended biopellet reactors are the Two Little Fishies Phosban Reactor, Aquatop Media Reactor with 95 GPH Pump, OCTO 2.5 Inch Media Reactor, Accel Aquatics BioPellet and Filter Media Reactor, and Marine Minimax Pro Series Media Reactor.
  • While not mandatory, using a protein skimmer alongside a biopellet reactor is recommended to remove bacterial waste produced by the reactor.

Don’t worry if you’re unfamiliar with this device, I’ll be going over the best biopellet reactors on the market so my prior misfortune doesn’t happen to you and enable you to decide on the right one for your fish tank.

On to the Reviews…

Top Pick

Two Little Fishies Phosban Reactor

This biopellet reactor from Two Little Fishes is ideal for tanks up to 150 gallons in volume as it can hold up to 200 grams of pellets or media.

Top Pick: Two Little Fishies Phosban Reactor

One of the best biopellet reactors to use for your fish tank is this one from Two Little Fishies as it’s both reliable and relatively affordable. It boasts a compact design, so it won’t fill up too much space.

The chamber can accommodate up to 200 grams of biopellets or media, making it a great pick for aquariums up to 150 gallons in volume. I really like how easy the biopellet reactor is to set up – the inlet and outlet 90-degree fittings can rotate to allow for a simple installation process.

As much as I like this biopellet reactor, the top lid on the device is quite flimsy and difficult to take off. This makes cleaning the interior a little challenging.

In addition, the fittings at the top can struggle to hold your tubing once the interior is filled with water, which can make it sometimes leak (especially if you hang it on the edge of your sump).

However, this occurs infrequently, so I don’t think it’s a huge problem – the device comes with a warranty, too!

I’d recommend placing the reactor inside your sump so you don’t end up with a mess to clean up if it does happen to leak.


  • Dimensions: Not specified
  • Weight: Not specified
  • Maximum Tank Size: 150 gallons


  • Compact design
  • Ideal for larger tanks
  • Easy setup
  • Inlet and outlet can be rotated


  • Cover is a little flimsy
  • Can be prone to leaking
Best Value

Aquatop Media Reactor with 95 GPH Pump

This high-quality biopellet reactor from Aquatop is both one of the most reliable and affordable reactors to purchase on the market.

Best Value: Aquatop Media Reactor with 95 GPH Pump

If you need a reliable and good-quality biopellet reactor with a low price point, you can’t go wrong with this biopellet reactor from Aquatop. It features a reverse water flow design, which prevents water channeling through your pellets/media and increases its efficiency.

The biopellet reactor can be used externally by attaching it to the side of your tank or inside your sump. It’s suitable for tanks up to 75 gallons in volume.

The reactor offers a stress-free setup to save you time as it comes with everything you need to get the unit up and running, including a pump, ring cover, necessary plumbing, and intake and output tubing.

You can adjust the water flow of the pump for up to 95 GPH (gallons per hour) too.

Unfortunately, the pump included with this reactor is a little restricting as it lacks power, so you may need to use a stronger pump to ensure the device will function properly.

That being said, if you have a basic setup and that doesn’t need ample flow, I think the provided pump will be sufficient!


  • Dimensions: 3.25” x 2.5” x 15”
  • Weight: 0.16 oz
  • Maximum Tank Size: 75 gallons


  • Low price point
  • Reverse water flow design
  • Easy to install as comes with all necessary equipment
  • Water flow on pump can be adjusted


  • Included pump isn’t the best quality
Editor’s Choice

OCTO 2.5 Inch Media Reactor

The Reef Octopus Media Reactor is one of the best biopellet reactors in terms of quality and effectiveness. It comes with a wide range of equipment compared to other reactors, including tubings, fittings, and a pump!

Editor’s Choice: OCTO 2.5 Inch Media Reactor

If you can afford to spend a little extra on a biopellet reactor for your fish tank, I fully recommend the Reef Octopus Media Reactor as it’s super high quality and reliable.

It can be used either externally on the side of your tank or internally inside your sump, making it very versatile. The Reef Octopus reactor is suitable for tanks up to 150 gallons in size, making it one of the best biopellet reactors for large setups!

I really appreciate the good selection (over 3!) of accessories you get with this reactor, especially when compared to other reactors – some don’t come with a pump or tubing!

It comes with all the necessary equipment you need to get started, including a pump with a max flow of 95 GPH, tubings and fittings – the only thing you need are the pellets!

However, the Reef Octopus Media Reactor doesn’t have the quickest installation process as it can be a bit difficult to set up. On the plus side, once you’ve finished assembling the device, it’s easy to use and works flawlessly for an extended period of time.


  • Dimensions: 14” x 10” x 4”
  • Weight: 2.55 lbs
  • Maximum Tank Size: 95 Gallons


  • Excellent quality
  • Comes with a good selection of accessories like tubings, fittings, and a pump
  • Ideal for large setups


  • Can be difficult to assemble

Accel Aquatics BioPellet and Filter Media Reactor

The Accel Aquatics Biopellet Reactor doesn’t need a super powerful or pricey water pump to be effective as it is able to create a strong enough flow on its own.

Accel Aquatics BioPellet and Filter Media Reactor

Another one of the top biopellet reactors on the market is the Accel Aquatics Biopellet Reactor, which provides superior performance without the need of a high-flow water pump – just a basic pump will do the trick!

The reactor features a unique flow accelerator inside the body that allows it to create a strong flow to churn the pellets and keep them suspended. It also has an inverted conical base that stops media and pellets from settling at the bottom of the reactor.

It has a large capacity (up to 300ml), so it can hold plenty of pellets or media. Bear in mind that this reactor doesn’t come with tubings or a pump, so you’ll need to purchase these separately. I personally use the Jebao DCT-6000 Marine Water Pump for my saltwater tanks.

In addition, the reactor is a little bulky in design, so this is something to keep in mind if you don’t have a lot of space or would prefer a more compact device.


  • Dimensions: 10.1” x 6.6” x 6.5”
  • Weight: 2.02 lbs
  • Maximum Tank Size: Not Specified


  • Unique flow accelerator design
  • Can hold a large amount of media or pellets
  • Conical base to stop pellets or media from clumping


  • Doesn’t include pumps, fittings, tubing, etc
  • Device is a little bulky

Marine Minimax Pro Series Media Reactor

The Marine Minimax Pro Series Media Reactor is one of the top biopellet reactors for a nano tank or aquarists with limited space due to its compact design. Better yet, these reactors come with energy-efficient pumps that can also have their water flow adjusted.

Marine Minimax Pro Series Media Reactor

Last but not least is the Innovative Marine Minimax Pro Series Media Reactor. Due to its small footprint, it’s one of the best biopellet reactors on the market for nano tanks.

It’s made from high-quality cell cast acrylic for durability and comes with a bracket so you can attach it to the side of your tank or place it inside your sump. It can hold up to 150 ml of pellets or media, which is a decent amount for small saltwater setups.

Included with the reactor is a pump with a flow control – the water flow can be changed from 10 to 52 GPH. My favorite feature about the Marine Minimax Pro Series Media Reactors is that the included pumps are energy efficient as they don’t consume a lot of power!

However, the flow control on this pump can be a little finicky to use as it needs to be adjusted regularly.


  • Dimensions: 11.8” x 4.4” x 4.4”
  • Weight: 1.1 lbs
  • Maximum Tank Size: Not Specified


  • Great reactor for nano tanks
  • Compact design
  • Flow on pump can be adjusted
  • Energy efficient


  • Flow control can be difficult to use

What Are Biopellet Reactors?

Biopellet reactors allow you to adjust the water flow through biopellets, which maximizes their ability to reduce nitrates and phosphates in your saltwater tank. Biopellets are made out of biodegradable polymers, which provide a carbon source to the beneficial bacteria in your aquarium.

The bacteria, which should already be present in a cycled tank, feed on the biopellets and begin forming colonies on them. This enables the bacteria to consume excess nitrates and phosphates.

What Does a Biopellet Reactor Do?

A biopellet reactor passes water through the biopellets to increase their efficiency at reducing phosphates and nitrates. Biopellets need constant motion to work as intended, which a reactor provides.

If the pellets are left to sit in an enclosed container without water flow, hydrogen sulfide can build up, which can be extremely harmful to your fish and corals in large quantities.

Why Buy a Biopellet Reactor?

The main reason to buy a biopellet reactor is so you can safely use biopellets in your tank. As mentioned earlier, biopellets reactors churn the pellets by passing water through them, which increases their efficiency at absorbing both nitrates and phosphates.

High phosphate and nitrate can wreak havoc in a saltwater tank, particularly reef setups containing corals, so biopellets are one of the most effective ways of keeping these levels low.

Advantages of Using A Biopellet Reactor In Your Aquarium

The biggest advantage of using a biopellet reactor in your tank is that it allows you to safely use biopellets to keep your nitrate and phosphate levels low.

What’s the Best Biopellet Reactor?

The best biopellet reactor mostly depends on the volume of your tank. Larger fish tanks will need more biopellets than smaller aquariums, and therefore a reactor with a capacity for bigger quantities of biopellets.

That being said, any of the devices featured above are a great place to start as they all boast superior performance and quality.


Do Biopellets Reduce Nitrates?

What do biopellets look like

Yes, biopellets do reduce nitrates in your tank! The pellets are made from biodegradable plastic, which acts as a carbon source for good bacteria to feed on.

This stimulates them to consume excess nitrates in your tank to keep levels within a safe range.

How Often Do You Need to Replace Biopellets?

It’s best to replace biopellets every 6 months as the good bacteria in your tank will eventually use up all the carbon.


Make sure you leave the existing pellets inside for at least a few weeks so you don’t eliminate the entirety of the good bacteria living on them all at once!

Do You Need a Protein Skimmer with a Biopellet Reactor?

Although not mandatory, it’s highly recommended to use a protein skimmer with a biopellet reactor as reactors produce a lot of bacterial waste, which a protein skimmer will help remove.

Where Should I Place a Biopellet Reactor?

It’s best to place your biopellet in a sump with a protein skimmer, ideally right next to the intake of your skimmer’s pump. However, if you don’t have a sump, you can also install your reactor on the side of your tank.

What’s the Right Biopellet Reactor Installation Process?

The right way to install your biopellet reactor will vary depending on the model, so be sure to check the manufacturer instructions your device came with to ensure it works as intended!

  • Simple installation
  • Compact design
  • Great for large tanks

  • Inexpensive
  • Comes with a water pump and other accessories
  • Reverse water flow design

Best Value

  • Inexpensive
  • Comes with a water pump and other accessories
  • Reverse water flow design

Editor’s Choice

Final Thoughts

I hope this guide helped you select the best biopellet reactors for your fish tank and gave you some helpful information on these devices in general. Which biopellet reactor is your favorite one to use?

I’d love to hear your thoughts over on our social media platforms. Be sure to share this post with other fellow fish fanatics so they can learn more about biopellet reactors, too!

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