Reservoir size for 260 sites?!

HOW MANY GALONS?
260 3.5 INCH SITES
I GOT 2X 3200/H GALONS PUMPS
i want to hav a reservoir to pump water in the tubes

and another reservoir for the drain lines that will be pumped back in the main reservoir
so what mean 3 pumps all togeter

i got 130 misters to feed( 1 for each 2 sites)

any suggestion ?!

pic to giv u a idea of what i need to feed