so here is my 75 G. sump design. i'm running a Magdrive 1800. and my return line is 2" PVC. i am heating the tank with two 300 Watt heaters. the open part of the sump will be used as a grow out for new fish, and growing plants...and my wet/dry area has 2000+ bio-balls, lavarock, and some sponges. so i've got a questions. should i be using a filter sock? and for those of you that do, how offten do you have to clean it out? thanks