My tests showed 8 hydros were not quite enough for each pool. With 12 have had a decent surplus. I occasionally toss a tablet in and take out half and feed it to one of my working pools. I just set up a stack 3 levels high on each side (and 'behind') feeding the pool on that side. Do need to remember to drop a world anchor though. I moved mine no realizing the portal stays active... but the hydro do not without an anchor. So portal is closed (pools drained) until I need it again.
Good point, I always forget about dang world anchors ha ha