Brand? I suspect activated carbon is one of those things manufactured by maybe two or three companies and distributed under hundreds of brand names kind of like refrigerators. Not a chemist, but what is activated carbon other than processed coal/charcoal? Not very complex to manufacture I'd say. Forgot what they do to it to make it 'activated'. My criteria for carbon is the size, shape and price. Since I don't have a sump, when I do run carbon I put it in a mesh bag in a canister filter. Therefore, I prefer the slightly larger stuff so none escapes through the mesh into the system.

Good point Mike!

the stuff that's always on-sale at Aquagiant.

is it ok to run carbon all the time or should you do it periodically?