who's all using it and how do you like it? Im interested too.
What's GFO?
I notice a alk drop when I add new gfo, that could be part of the sps tip burn you will see if you add too much initially other than dropping the phosphates too quickly. I also had problems with carbon dosing, seemed like the acros flesh was getting thinner as they became very sensitive to alk swings and lighting.
Hows purigen work for you? I run gfo and carbon.