I'm having some difficulty with maintaining stable GH and pH in one of my nano tanks due to the seriyu stone used in hardscape. So, though I really didn't want to go this route, I'm considering purchasing yet another piece of equipment. Anyone have any recommendations on an RO unit? Does it need to include DI? I have going two 6 gallon and one 12 gallon tanks so the output does not need to be large. My greatest consideration is ease of use. I would like as close to "plug and play" as possible.