I've been using one for a few months now for my 75
gal tank with no issues at all,...just get the biggest one you can that'll fit under your tank,....I put my reactor in the middle section and my return pump in the last section,....also buy an extra pair of the filter socks or two,,..they get gunked out pretty quick, that way you can put in a clean set when you do your weekly
pwc while you're cleaning out the other ones ( soak 'em in a pail of water with some bleach, hose'em off good and then air them out for a few days)... Hope this helps, Dary