PO4x4 Comparison with Traditional GFO


We were given a bag of the new PO4x4 phosphate remover from our pals at Aquarium Specialty, and after a trying it out for several weeks we are finally comfortable with developing an opinion on the product. To start out our review, we wanted to compare the PO4x4 with a more traditional media like granular ferric oxide (GFO), and we found the differences to be fairly significant. Instead of being an iron based flake-like material, the PO4x4 is actually a spherical synthetic polymer. It is said to not leach phosphate back into the aquarium like GFO and claims to consume up to four times the phosphate. While these claim are fairly difficult to test with general aquarium products, we were able to see how nicely the media played with our media reactors.

We placed the PO4x4 media into a Phosban 150 media reactor and fed it with a Maxi-Jet 400 powerhead. This is a very common setup for aquarium keepers to use and we felt it would be a great tool to test with. Upon inspecting the media prior to filling the reactor, we felt the individual grains were too small for a single layer of the filter sponge provided with the reactor. Improvising, we took the sponge that normally sits in the top of the reactor and made a double layer at the bottom. Despite some of the granules still falling into the sponge, the double layer did keep them off the bottom of the reactor for the most part while also still allowing ample water flow through.

The media seems to be very light in the water flow. By that I mean it gets easily agitated and can stay suspended in the water. This proved to be a slight issue, especially since we relocated the top layer of foam to the bottom of the reactor. When trying to adjust the flow and setting the reactor up for the first time, some of the media did manage to escape through the outlet. It happened once again after doing some maintenance in the tank when the foam pads clogged, forcing them to move up the reactor and dumping all of the PO4x4 beads into the sump. This caused the tank to become a little cloudy, but that cloudiness disappeared shortly after the loose media was siphoned out of the sump. Since those two minor incidents, which were entirely our fault due to not having the proper reactor setup, we haven’t experienced any issues.

The one thing we really liked about the PO4x4 is the fact that it doesn’t crumble and break apart when tumbled, a common issue with GFO. As can be seen in the video above, we had a decent amount of flow through the media, causing it to tumble rather violently in some spots. The media doesn’t clump together at all, but does have a tendency of clogging up larger pores on foam sponges. Additionally, the media seems to do a pretty good job of removing phosphate.  We don’t have exact numbers, but judging by the decreased presence of nuisance algae and improved coral growth rates without changing many other tank parameters, we can say without doubt that it does remove phosphate.


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