From what I have been told, all GFO is made by just a couple companies in the world. Most GFO is used for aresenic removal in potable water supplies, and is sold under a product name Bayoxide E-33. The BRS GFO is supposed to be the same stuff as the Rowa, but without the cost associated with being a Deltec product. I stopped using the Rowa product and started with the BRS stuff after learning it was the same thing, but a lot less expensive. From the BRS Website:
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We purchase our Granular Ferric Oxide (GFO) directly from the manufacturer allowing us to offer it for a fraction of the cost. This is the same material imported from Germany for the aquarium industry. - - GFO is primarily used to remove phosphates from your aquarium but will remove arsenic and heavy metals as well. By removing phosphates GFO aids in algae control and will encourage faster coral growth. - - High Capacity GFO is our premium GFO and comes with several distinct advantages over the other GFO's. HC GFO is able to remove roughly twice as much phosphate for the same volume of material. This means it will last longer and require less maintenance. The particles are extremely hard and even better then the Pelletized GFO at reducing the effects of water abrasion. HC GFO works very well in both a reactor and filter bag. If you are going to be using a filter bag with your GFO this is the preferred product.
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Edit:
Schwaggs;669388 wrote: I agree that the granular is messy and gets everywhere. I dump as much as I can get out into a plastic bag (recycled bag from the LFS) and take the reactor into the back yard and use the hose to rinse all the left over granules and rinse out the foam pads.
I use a single BRS Media reactor for my GFO, and I had the issue of fines getting into the sump. You can have the GFO reactor dump into a second container, then the water overflows into the sump, and the fines stay in the second container, since they are heavier than water and sink. I use a 50 micron filter bag and that catches all the fines, and I just rinse the bag out every once in a while.
Another option is to put the GFO reactor inline with a carbon reactor and have the GFO reactor output pass into the carbon reactor, where the GFO fines are caught in the carbon reactor