The Cobalt Aquatics E-X-T GFO filter sponge is a new chemical filter from Cobalt Aquatics with phosphate remover built right in. Filter pads impregnated with chemical media have been around for years, but to date the mediums used have been zeolite for ammonia removal in freshwater and carbon for overall removal of dissolved organics and nitrate removers.
Granular Ferric Oxide, or GFO as it is more often called, has become the de facto method for removing phosphate from aquarium water. The E-X-T GFO filter sponge is the first material of its kind to have granules of ferric oxide incorporated directly into the sponge fibers. Cobalt Aquatics states that a single GFO filter sponge is equivalent to 15 oz. of actual granular ferric oxide, but we’re guessing they’re not making a comparison to high-performance GFO like ROWA.
Like other chemical filter pads, the best bang for your buck is always going to be to use the pure media itself while filter pads offer a level of convenience that is appealing to casual aquarists or for use in tanks with very modest chemical filtration needs. Cobalt Aquatics E-X-T GFO Filter Sponge is cut to fit their super simple E-X-T canister filter but there’s no reason you won’t be able to cut and or stuff the GFO sponge inside filters and filtration chambers of smaller reef aquariums.