Either really considering they will not push 500 or 700gph. 500 may be safer, I have a mag drive 1800 gph pushing mine t'ed off of course, but it's flow is set by the choke points at the 3/4" unions
the 20 inc hfilter is big enough to run the 500 gph.. i'd extend the tubing as far down as possible though![]()
get a sponge with bigger pores, something like aquaclear sponge.Agreed with the inside tubing length... as far as the sponge goes at the bottom of the tube, should i just wait and see how my co2 is dissolving or just go ahead and do it...i dont want to restrict any flow by it getting clogged up eventually?