Need help with sump/fuge

[TheReefGeek]

?? dude what are you talking about? abs float valves are gravity fed, no hydraulics, no pressure and you don't need a backup system. it floats, when it needs water it opens a seal and water flows thru when it gets up to level it shuts off. there is littlerly no safer or user friendly fail safe system better that an abs float valve.

Im talking about an auto top off with an RODI unit, which a single abs float valve is not going to do. If you think it will, please explain in DETAIL.

You would need to install a hydraulic valve that triggers when there is pressure build-up in the line, and the valve closes the waste water production for you. Otherwise, when your abs float valve closes, your RODI unit just keeps on pumping out waste water.

Float valves can fail open, if anything clogs them from closing properly, then water just keep on flowing!