I got this timer from HomeDepot ($19 Intermatic DT17 7Day Digital Programmable) and I set it up to run 1 minute per hour during the night pumping in a kalwasser mix. I hooked it to one of the "Toms" water pumps ($14 at LFS) and has worked like a charm. Just adjust the minutes to compensate for amount needed.
I just started using a 2 liter bottle so that I could not overflow the thank. I have 3 float switches but decided to try and make this work without them (simplicity). I now have 3 float switches I do not need.
EDIT: I already know how much my tank evaporates each day. I top off with Kalwasser at night to keep PH up. With my jug a ways from the tank, it only adds about 2ounces per minute.
I am going to get a second timer to top off during day with straight RO/DI to keep level just a bit more stable. Guess this is my twin dosing system
