Okay...Az, one last question, because I appreciate your effort on this. I want to go ahead and order the RO unit, but I want to be sure I get what I need. This will be for the fish tanks only, and not ever for drinking water. I'd want a unit that will give me about forty-gallons for when I do a water change. I'd be able to accumulate this amount of water over some days before I do a water change, so I don't need a very big unit. At the same time, I want water that will be very good for the overall health of the tanks, the largest of which is 120-gallons. So, could you tell me which manufacturer and model I should chose for these purposes? I'd be willing to spend the money for a great one like the Spectapure MaxCap-RO-DI, but I'd very much appreciate it if you could recommend something specific (even if it is the MaxCap 90 if that be the case) so that I don't do any unnecessary overkill in terms of water quality, size and or cost. THANKS again.