25gal Starfire

[Delphinus]

Carbon and biopellets are two independent things. Biopellets are a place for bacteria to colonize that feed off nutrients. It's like adding a bunch of live rock in your tank except they fit in a nice small reactor. Carbon on the other hand remove organics (not just nutrients) which can cause things such as yellowing of water (water always looks "polished" and "clear" after changing carbon) as well as impeding the growth of certain corals (some organics may not necessarily break down into ammonia/nitrite/nitrate and thus might not otherwise be skimmed or metabolized out of the system).

Basically I think carbon should still be run regardless whether you add pellets or not - there isn't really any overlap between the two. Biopellets and GFO on the other hand ... there might be an overlap there.

HTH