I am drilling holes in the top back of tank and was wondering if there is a better place to put them. I was going to run return to middle pointing up so it will give top water movement then place my 2 Korlias on the sides. Does that sound good? I was thinking of placing other one directly up back of tank vertical with the skimmer in sump. I know I should put them pretty close to top but is there a certain amount of inches it needs to be to be more sufficient? Thanks.