Product Review: AquaMaxx biopellet reactor

When I first got the AquaMaxx Biopellet Reactor, I was very interested in how it worked because the demonstration unit on display showcased something unseen by other similar devices. Unlike its counterparts, this one causes the media to spin at a strong rate — the pellets orbiting a vertical riser tube provide one-way directional flow. It looked really neat, but I didn’t know how the media would do under such conditions. The reactor itself is made of acrylic and PVC fittings. The inlet and outlets are glued into place, which I personally don’t like as it forces the hobbyist to plumb it specifically to its configuration. I’d rather have the freedom to run lines as they suit my needs, but I’m quibbling over a very minor design decision. The fittings use hose barb connectors, and I used two different sizes of flexible vinyl tubing to match that connection. If you’d prefer to hard plumb it, the hose barbs can be omitted, but you’ll have to use unions with nipples to remove the reactor for maintenance.  To open the reactor for cleaning, filling or refilling, there are a six plastic knurled slotted screws that fit keyhole slots. Using a flathead screwdriver, loosen the screws enough to rotate the lid half an inch, then lift it off. The screw heads aren’t big enough to do this by hand, but once loosened you can back them out using your finger tips.  Within the chamber, an upper flow plate or screen keeps the pellets from flowing out of the reactor, especially if some of the float. The plate can be extracted with something thin, like a paper clip fashioned into a hook for example. Once this plate is out of the way, the reactor can be filled up with media. I’ve run three types of media in this reactor: Vertex, BioSpheres, and EcoBak pellets. None did better than the other brands, and all worked as advertised.  The bottom plate is screwed to the riser tube using two long plastic screws. Above that plate are a few stacked plastic parts that resemble fat washers, with a narrow slot traversing each one. The water pushes through these slots, creating that rotational flow that makes the beads spin.  When running a biopellet reactor, often some type of brown fuzzy growth appears in certain spots, including the upper plate. This is more than likely caused by bacteria, since the collective mass doesn’t settle at the base like detritus might do. About every five months, I’ll open up the reactor to remove and clean that upper plate to prevent obstructed flow. That’s a good time to add additional media to the reactor. If the entire unit looks like it could use a thorough cleaning, I’ll pour the remaining pellets into a container with some saltwater, and then disassemble and wipe down the entire reactor in and out.  I run the AquaMaxx Biopellet Reactor in my sump, but never had a leak to contend with. Using a ball valve from the manifold assembly, about 500gph of water flows through the reactor via vinyl tubing. The output of the reactor runs directly into the intake of the protein skimmer’s pump, to skim 100% of the reactor’s effluent. Every two weeks, I dose my tank with bacteria (Prodibio) and the sandbed stays nice and clean. The reactor has kept up well with the needs of my 400g system, as well as the 215g temporary tank that has 28 fish in a mixed reef. More about my Prodibio dosing here:…dibio-Products Filling up the reactor isn’t hard. Remove the lid, and the upper screen plate. I use a canning funnel and a large plastic test tube to avoid sending any pellets down the central riser tube.  The pellets were soaked overnight, drained, and then poured into the reactor. Because I still had some from the previous batch, these were added as well. The new media is larger and heavier, thus the older media usually floats to the upper section. In these pictures, 1000ml worth of EcoBak filled the reactor less than halfway. It was filled with RO water prior to installing it in my sump.  I’ve used this reactor for over 10 months, and twice cleaned it completely in that time. During the cleanings, the only area that I’d advise caution is the two screws at the bottom of the riser tube, as they resisted as I unscrewed and later screwed them back into place. It would be a shame to shear off a screw head, thus damaging the innards and requiring the need to order parts and wait for these to arrive. Be careful, or perhaps it would be best to run the reactor in a vinegar water solution instead so those slits in the riser’s flow section will clean out on their own, only needing a quick rinse thereafter. I’ve come to like the orbiting pellets in the reactor because it allows me to check the flow at a glance. If too much flow is injected into the reactor, the pellets appear to be more buoyant, causing them to collect near the upper plate. It would be better to use enough flow to cause them to move in suspension, but not to the point that the entire reactor appears filled to the top with media like a snow globe. If too many get trapped near the top, they may get stuck up there requiring disassembly to sink them back down. Biopellets deplete over time, and in this reactor you may not notice how much initially. Turning off the flow for a few seconds will allow you to gauge how much has been consumed by the bacteria, and replenish as necessary. For example in the following pictures, the left image shows how much media the reactor has, while the right image implies it is more packed with pellets with the water flow on.  The AquaMaxx Biopellet Reactor is a good choice for a reef keeper seeking a carbon dosing regime. It is easy to install, and feels solid. With proper care, it should last for years. This product was provided to me free of charge for the purpose of this product review.

Marc Levenson

About Marc Levenson

Based out of Fort Worth, Texas, I've been a hobbyist for more than 13 years. I enjoy helping others via my two websites & These feature articles, pictures, podcasts, interviews and product reviews, as well as documentation of personal experience maintaining tanks ranging from 3g to 400g. I make a living selling RO/DI systems and acrylic wares (sumps, frag tanks, overflows, photoboxes), which permits me to enjoy the hobby more. I'm a member of DFWMAS and have served on the board of directors for seven years, doing what I can to encourage growth while keeping it fun. My articles have appeared in print & online, and I'm happy to be blogging on as well.
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