Okay, newbie here. Just got my tank set up (150g w/ sump, 600 gph overflow, 600 gph return pump (yeah I know, need a bigger one), 3-4" sand bed w/plenum, 70lbs. base rock, 88 lbs live rock). Just starting to cycle and work all the kinks out. I drilled a small hole about 1/2" above the end of...