Pump Issues

[Kronk]

I glued all the PVC together and fit the softpipe section onto the barbs with a heat gun and ty-wraps. Any easy ways to check for air leaks? I left the pump off for a few hours and there was no moisture on any of the connections.

I do have a 90 right off the end of the pump for the intake but how would this allow air into the lines?

I am starting to think its the pump... it is pretty old by the looks of it and they sell new O rings online so I am thinking that O ring is a seal that keeps the air out which is failing. It would be a bummer if it was the pump cause its the second one I have bought for this tank. The first was a Q1 3000 which was way underpowered. Might get a Q1 6000 if I cant find a fix in the next week or so, JL has it onsale.