greenhouse-tomatoes: DR. FICUS NEEDS HELP

Aloha:

The facts are; I have a 10 Gallon Fertilizer reservoir tank with an ordinary toilet float ball valve. In line, is an ordinary flow thru water meter. Everything has worked well until I installed a R/O System with a 4 Gallon Pressurized holding tank. Now, the pure water dribbles into the reservoir tank as the level declines by 5 or 6 ounces and the float ball drops. Because of the very low flow and low pressure the water meter does not record the flow. I have tried to replumb the system to mesure the waste water and with a little extrapolation, 4 or 5 times the pure water, try to figure how much pure water has been introduced into the reservoir tank. A cumbersome and unmanageable approach. I have yet to find a meter that records such minimal R/O flows until about $300 to $400.

Here is where you can help, I hope. What system either mechanical or electrical, I'd prefer the former can be designed that will shut off the water flow when the water level reaches the top of the tank (which of course is what occurs now) and does NOT permit water to flow into the tank until the level drops, say 3" inches or so? Then, it should open up fully to fill the tank. Here's why. When the tank is full and I PUSH down on the float ball the Pressurized water flows thru with sufficient force and volume to run the meter. All that I need is a system to stop the water flow at the top and start it again after a 3" or so drop. The best solution entitles you to lunch for two in Maui.

Mahalo Nui Loa

Dr. Ficus Hydroponicus

aka Morrie