just hook your pond pumps to fsih tank floats. i have a old system that used bathroom toilet floats there totally adjustable for height if you by the new style and no big floats any more on them.
sound so me like what you should be doing is a deep water system with just air stones in it and no pumps its the best system by far and almost no faluire possiblity. just use plastic totes i like the 30 gallon ones. cut a piece of foam that is 4 inches thick to fit in the tote and hole saw spots for net pots to fit in the foam. drop in one $9 wally world fish air
pump and now your plants are floating so teh water level is always perfect and you just add water as it needs it to keep it full.
You just cant get a bad grow out of this system.