I have an old commercial pool with a surge tank where all the equipment, water feed, etc are in a room located about 30 feet from the pool. The tank seems undersized, not sure, but the water level sinks about 12-15 inches when the pump is turned on and will fluctuate approximately 4-6 inches based on a clean filter till it needs cleaned. The tank is round, about 20 inches in the inside diameter. See similar attached diagram.
I previous tried an old style toilet valve with the rod and float. It would not stay stable and overfilled often not matter how many adjustments. The water level in the tank just fluctuated too much. I don't think the fluid master style valves will work.
The pool has a drip edge system and needs to stay very consistent.
[attachment=0:3kc4nzve]Typical Concrete Storage Tk.jpg[/attachment:3kc4nzve]