i'm taking care of some of the tanks at my school and i've exclusively used flourish and turface as a plant substrate. how does eco-complete work? i can't even run a python around it b/c i find it's too finely grained. I'm having a little trouble growing plants and while I realize it could be for a variety of reasons, my question is if you need to replace eco-complete after a while. I think the one in the tank is about 2 years old.