Talk to your well driller to see if there is a way to keep water pressure in the house (and fill the bladder tanks) AND run a goodly volume of water to the pond at the same time. If he says yes, please let me know how to do it.
Is the 70 gpm based on the pump(s) rating, or actual water pumped?
I'm putting 25 gpm into my sand soil dug pond now, and all it will do is keep the level the same - it can't raise the pond level any. If I want water pressure in the house, I have to shut off the water to the pond. I'd get as close to the 70 gpm limit as you could.
