Hello fellow hobbyists. I need some help and I hope anybody here can help me. It is the very annoying LOUD gurgling noise problem with my overflow filtration system. Tank specs: 187 gallons with one overflow into a sump with a 5 box type filter (a filter system with 5 separate compartments of water) with 2 drainage pipes Pump is 900 GPH Einheim (spelling) pumping back out from one hose/pipe system. FINDINGS: the gurgling noise is coming out of the air intake HOLE of pipe # 2 (see diagram below). I attached a picture of the current configuration and some solutions I already tried including: 1- Attaching air intake hose (3 ft) into air intake hole for pipe # 2. Gurgling noise stops, but pipe 1 stops working, so the sump only has 1 pipe draining instead of 2 pipes (which is a requirement). 2- Lowering the ball valve so that only a little water flows out from the sump back into the tank. Gurgling noise stops. Both pipes 1 and 2 works and drains water. BUT, the pump is overtaxed because backward pressue is being forced back into the pump because the ball valve is almost 90% closed to only allow a little water back into the tank. This broke my first pump after 2 or 3 days. So, adjusting the ball valve does not solve the problem. It will only break the pump after a few days. Also, the GPH flowrate will be so low as to make the fish tank become unhealthy. I need at least a 4 or 5 times turnover rate for the fish tank filtration system. What other solutions are there to this annoying problem? I have tried asking my local saltwater fish store for help and the fish tank seller for help. No one has been able to help me. The manager of the store is on holiday, so I have to wait 2 weeks. I want to solve this problem now, with the help of this forum and the participants. I sincerely appreciate any comments, help, or tips you can give me.