advice on a DIY water top off system

[Douglas]

I would perfer to go to a resevior, then have it pumped, when needed into the sump. I've heard that having your RO unit directly hooked up to the sump, is a recipie for disaster.(just what I've read, don't know for a fact) I don't really have a lot of room above my sump. I have the abilitly to hide it, in another room close to the tank. So I'm looking for ideas for containers, floats, and pumping units, within a reasonable cost. Doug