Well, I got a new 29 gallon (for free!), and I'm trying to set it up cheaply. Or at least relatively cheaply. I was wondering if, as a substrate, i could do just plain potting soil, topped with about two bags of eco complete I have from previous tanks. I've never used potting soil before, but I've read somewhere it can be done, and I was thinking the eco on top might help keep it from dirtying up everything all the time. Any advice, experience, or thoughts would be appreciated. Thanks.