cunfused about how many types of GFO? 2 or 4?

Ralph ATL

Formerly mysterybox
I was always under the impression that there are only 2 types of GFO, pellet and granular, however Warner Marine & bulkreefsupply both sell a HC (high capacity) version, and ROWA is darker & moist. So how many types are there? I use the HC, it seems to be a little more efficient.


Premium Member
There are a number of types from at least a couple of manufacturers, and some aquarium companies post-treat their products.