autotopoff.com sells float switches that can control anything electrically for a good price. That would work well for the top off.
For the RODI
system, you can install float valves to shut off the "good" water, and a auto shut off valve that will also shut off the waste water line (you need both or the waste water will just keep on running).
I have a similar system to what you are talking about set up, but I put my containers up high so I can just gravity feed to the sump for PWCs and to the ATO container for top offs. Do you already have an ATO container setup?
Here is how mine is setup:
Containers are 12 gal
water containers, and I installed bulkheads on the bottom with hose barbs.
Each tank has 2 holes I drilled in the top sides: 1 for the float valve that shuts off the RODI
system, and the other is just a bulkhead with a hose that goes to the drain, installed above the float valve, in case of failure (so the water will just run to the drain in the event of a shutoff failure, instead of on the floor).
All parts besides the RODI
unit I got at Grainger.
For my ATO container, I just used an RV water storage tank, 10 gallons
, and in aqualifter hooked to a float switch installed in the sump.
I spray painted it black to match my speakers and aquarium cabinet, so you can hardly tell its back there. Since I painted it black it is impossible to tell how much water is left, so I added a float gauge to tell me how much water is left and tell me when full during filling.
All in all, it takes me about 10 minutes to unwind the 30' hose, fill the ATO container, pull 10 gallons out via a few buckets and a siphon, and run SW
back into the tank for replacement. All the RODI
stuff in the laundry turns off automatically so dont have to watch it too close. I just turn it on at night and turn it off the next night. I just have a 3 way valve to determine which tank will fill.
Hopefully that might give you some ideas...