The tank was actually drilled in the bottom. It is a 1 inch bulkhead, so the hole drilled acommadates that. A plumbing company has offered to give me a 17 inch piece of 6 inch pvc, so I am going to cut it in half and try to use that. Thanks for the advice on the air hole size. I have experience with saltwater tanks, and have had success with only HOB filters. This will be my first try at a sump. I had a 125 gallon FOWLR and a 29 with some softies and I shut them down a little over a year ago to go back to school for nursing. But I can't go without a saltwater tank any longer, so I wanted to crank back up the 29 gallon and try to do it right with a sump. Right now I have a 20 gallon long with a HOB filter and I want to move them to the 29 gallon. I am going to use a mag 3 that came off of my aqua c urchine skimmer, do you think this will work. I am a little nervous and intimidated about trying to use a sump, so wish me luck. Any advice is appreciated and I will post pictures of the process if any one is interested. I think I did a pretty good job on building my own sump, for a girl. Of course I did cut my hand open trying to take one of the glass dividers out that I put in the wrong place.