I know very little about the RO/DI systems to be completely honest. I have read before it wont take the salt out of the water so I wanted to ask a few questions. Can I cycle tank water through one on a schedule? I am sure I could plump in a pump for optimal pressure and just have it feed back into my sump but is there a benefit from doing this say once a week? If so I would assume I would need to supplement the water? Would this affect anything or is it worth doing?