WTF - Here is one for more before I call it a day.
Now that your cell and circulation tank are under a vacuum, adding water to the tanks is simple since no pump is needed. Do what I do:
Get a fuel injector from a junkyard for 5 bucks. It is nothing more than a little valve. Use a 555 to drive a 2N3055 to pulse it on and off every second so you don't destroy the vacuum. It only lets a small amount of water in at a time.
The circulation tank should be slightly above your cell so water drains down into the cell and the gas bubbles up into the upper section of the circulation tank. The circulation tank is the place you add water. A float sensor to enable the 555 or a mechanical float valve from a toilet may also work just fine.
Place a splash barrier between the pump inlet on the bottom of the circulation tank and the pump outlet above the barrier. It could be low density foam or SS mesh.
I drew a diagram a while back and I will post pictures in a few days once my domain name is hidden behind a proxy register. Keeps the crazies out of my yard.
