Hey guys. My name is Kasey and I joined this forum with hopes that someone can help me kick start my aquarium. I recently moved to Hawaii so I don't really know anyone here to help me, so here goes. I have a 60 gal Deep Blue rimless tank with a 30 gal sump. I decided to go with all hard plumbing because I really felt like it would like nice when I was done. Which it does. I did a dry run before I connected the final piece and it seemed to work fine. I connected the return plumbing to my tank, and after an initial burst of air, all I get is a trickle of water, if I am lucky. So I started troubleshooting. I installed two unions, one just downstream of the pump, the other just downstream of the check valve. I disconnected the union just downstream of the pump, rush of water, works fine. I connected the check valve, rush of water, works fine. I have a 90 degree fitting downstream of the check valve that is kind of a t fitting, it has a 1/2" connector and gate valve downstream of it that remains shut and is capped off if I am not doing water changes (all hypothetical, obviously my system doesn't work) But I did use it to drain the line down from the return line in the tank and then turned the pump on and water flows fine through there as well. I am at a loss. The pump will not put water into my tank. Every 10th time I turn on the tank it sounds like sudden rush of air through the return line in my tank, and then nothing, just bubbles. Please help.