[Wombii]

I don't know if it's relevant to you, or if you've already considered it, but I stumbled upon some older notes. I originally wanted to use a gear pump that could run both ways, and considered using one way check valves. The most basic would be to have side A be monitor and draft with opposite one ways and side B to tank. Running the pump one direction would spray water from the tank and the other direction would fill the tank. There are one way check valves on ebay down to 1mm now. Might save you some solenoids if it works.