I use carbon in my mixed reef system as a precaution to hopefully remove any toxins released by my softies before they can harm my SPS. I've been using the Aqua-Tech stuff from WalMart. I just got back from buying 4 9oz bottles for $5.88 each. I thought that was a little high so I checked bulkreefsupply and they have three different products: Lignite, Bituminous, and Premium ROX 0.8. Has anyone used either to compare?