Purigen is like GAC
on steriods. Plus it does not release any toxins back into the water once it's used up.
Yes Chemi Pure is similar in it's action, but it also claims to remove any traces of copper. It also has ferric oxide which is supposed to remove silicate and Phosphates.
I figure that with the $ I have spent on livestock/corals/equipment, whts a few more bucks for some extra filtration media.
I just started using the Chemi Pure beacuse I wanted to try to get my nitrates down closer to zero (along with my weekly PWC
's). If it doesnt work..I'll try something else.