Aquarium Fish

Biopellet Aquarium Filter

Biopellet aquarium filters are one of the more recent new products to hit the market for saltwater aquarium keepers. The manufacturers claim that these pellets will reduce the level of nitrate and phosphates in your aquarium. Why do hobbyists want reduced nitrates and reduced phosphates? Primarily to keep nuisance algae from growing in their tanks and because nitrates and phosphates can negatively impact the growth rates of some corals.

How do they work? Well, basically the manufacturers claim that these pellets provide places for bacteria to grow which consume nitrates and phosphates. As the bacteria multiply and grow they consume the carbon in the biodegradable pellets. Kind of cool huh? Supposedly, these bio degradable polymers were first used in sewage treatment plants.

Saltwater reef keepers have utilized a carbon dosing regimen called vodka dosing for years. The problem with vodka dosing is that you have to do it all the time! With biopellets you put them in a reactor and they will slowly dissolve over time. About the only maintenance you will perform on a daily basis is to look at the reactor and make sure the pellets are tumbling correctly. So, running with the pellets is less time consuming and potentially less error prone than vodka dosing.

As these catch on, more and more manufacturers are making them. As of June 2011 here are some of the brands available:

  • Two Little Fishies NPX
  • Sea-slug Phosballs
  • Warner Marine Eco bak
  • Brightwell Katalyst
  • NP (the original and first pellet manufacturer?)
  • Reef Dynamics NOPO
  • Aqua Vision Aquatics
  • Reef Octopus Bio Spheres
  • ATB HQ

These pellets are made to be used in a fluidized filter. The Two Little Fishies Phosban reactor is an ideal first choice for many hobbyists to run them in because it is inexpensive and readily available. There are other reactors (reef octopus, warner marine, brs, geo, nextreef, etc) out there and they can be quite costly but some of the more expensive models come with added features that you don't get with the TLF reactors. However, for our purposes the TLF reactors will work just fine.


biopellet reactor biopellet reactor screen

To test them out I started with a phosban 150 reactor made by two little fishies. You can use a maxi-jet 1200 power head to pump the water thru the reactor. The reactor comes with a nozzle to let you adjust the flow of water entering the reactor. To set up the reactor here is what I did:

  • soaked the pellets in RO water for about 2 hours. I had heard that this would prevent them from clumping and floating in the reactor.
  • while waiting for the pellets to soak I added the mesh screens to the red plates of the reactor. I am not and do not recommend using the sponges that come with the reactor. They will clog up too fast and really limit the flow.
  • tested my water for phosphates using a hanna digital phosphate checker and tested my nitrates using a Salifert test kit.
  • slowly and carefully added them to the reactor. You have to cover the middle tube of the reactor so you don't get any pellets in it.
  • cut your rubber tubing to the lengths you need and hook up your power head to the input line and direct the output line to the protein skimmer (very important) so that your skimmer has first crack at the water exiting the biopellet reactor.
  • plug in the power head and slowly open the valve on the reactor to slowly let water enter it. Doing this slowly will help keep the pellets toward the bottom of the reactor. You are aiming for a tumbling action for the pellets.

For the pellets I picked up one bag of the Two Little Fishies NPX and one bag of the NP Biopellets bags. I wanted to see the differences in how the different brands would tumble in the reactors.


  • Pellets not tumbling? If your pellets are not tumbling but your valve is all the way open you either have too many pellets in the reactor or you need a more powerful power head.
  • No noticeable decrease in algae growth? Make sure you have enough pellets for a system your size and that you are directing the output to the skimmer before it re-enters the tank.
  • pH decreasing? Probably due to the influx of bacteria - is your protein skimmer pulling out the gunk the reactors are producing. Is your skimmer powerful enough?
  • Algae growing in the main tank? If so, are you directing the reactor output line to the skimmer first? Are you using enough pellets?
  • Cloudy water? Could be attributed to a bacterial bloom. Give the system a couple of days to stabilize before doing anything drastic. Things should settle down over a couple of days and the cloudiness will go away. If it won't go away make sure you are doing all of the other things mentioned above and maybe slow the flow thru the reactor or even remove the amount of pellets you are using.
  • Not getting good results? Nitrates and/or phosphates not going down? Have you given the pellets a long enough chance to work? Leave them running for several months. It takes time for these pellets to really start working and for your tank to stabilize.

How much is this going to cost?
A 500 ml bag costs around $40 dollars. Manufacturers recommend 250 ml per 50 gallons. I would not put more than 200 to 300 ml in a TLF 150 reactor in order to get the pellets tumbling nicely so you will need multiple reactors. Lets use a 120 gallon for an example:

Using multiple TLF 150 reactors
  • Need 2 bags of pellets in order to run 750 ml of pellets on the system per the mfg recommendations = $80
  • Need 3 reactors @ $40 a piece = $120
  • Need 3 maxi-jet 1200 power heads to run the reactors = $60 (3 x $20 a piece)
  • Total comes out to about $260.

Using one TLF 550 reactor
  • 2 bags of pellets = $80
  • TLF 550 reactor = $60
  • 1/2 inch ID power head to run the 550 = $60
  • Total comes to $200 and you have 1 reactor in your sump

The only problem I had when using just the TLF 550 reactor was the flow rate. I've used both the 150 and the 550 and totally prefer several 150's over one 550 due to the better tumbling action of the pellets in the TLF 150 reactor.

biopellet reactors in sump hoses going into protein skimmer tumbling biopellets

I have been running these pellets since January 2011 on a 120 gallon tank that is very heavily stocked for a reef tank. I also feed my fish and anemones very heavily twice a day. I can say without a doubt that these biopellets are working very well at keeping my nitrates and phosphates at very low levels and my tank has little to no algae growing in it. I test my water weekly and my nitrates are always nil, while the phosphates fluctuate between .03 and .08 ppm on the hanna meter. Before the introduction of the pellets the hanna meter would display phosphate readings double and triple what I'm getting now. I do a quick wipe down of the front and side glass about twice a week with the mag-float. The gunk collected in my skimmer is gag inducing and some of the nastiest looking, smelly stuff that I've seen my octopus skimmer pull out of my tank. The sps frags look phenomenal and have great polyp extension. Saltwater hobbyists all over the net are reporting similar success stories. Time will tell, but these pellets just might be the biggest thing since the protein skimmer for reef tank keepers.

Happy Reef Keeping!

By : Mike FishLore

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