Tricky air leak


Jul 11, 2013
So my pool has been operating perfectly for many years, and I’m fairly well educated on pool knowledge and DIY fixes. I’ve opened and closed my pool for years and tracked down and fixed many problems including air leaks, and priming issues.

So with that in mind, I decided to help a friend open their pool in the house they bought. 15x30 inground gunite pool with single skimmer (no main drain), two return jets plus slide, broken Heater, Hayward 1.5hp super pump, and Hayward 3600 de filter. Pool is ancient and although it was properly closed, it looks like the previous owners didn’t keep track of stuff, and there was a lot of stuff missing.

Opened up the de filter before starting the season and there was ripped grids, so we replaced all of them with a new set. The heater is long broken, so it isn’t set up, but the return lines are still plumbed through the heater. Opened up the pool, set everything up, and the pump primed immediately. Filter pressure is pretty high however at 20-22psi however I think that’s partially due to a way overpowered 1.5hp pump on a single skimmer with 1.5” suction line. You can feel how intense the returns are so I’m sure it’s grossly overpowered.
We replaced the gasket on the pump lid, and checked the union pre pump with shaving cream and I see no suction leaks before it goes underground.

However, after priming the pump, and getting everything flowing, you can still see noticeable air intrusion in the pump basket with air bubbles coming out of the returns. Bleeding the airout of the top of thefilter does make a noticeable change in the amount of air coming out of the returns, but within 10 minutes it goes back to bubbles out of the returns again.

To top it off, the pump is losing its prime and increasing pressure over the course of 4ish hours to the point of having almost no water coming into the pump, and no pressure on the returns.
Shutting the pump down for 10 minutes, then turning back on, and everything goes back to normal until it starts the 4 hour cycle again and back to no flow.

Suction leak between skimmer and pump underground? Going from filter to recirculate did seem to decrease the amount of air strange enough though. But I’m not sure if it’s just me noticing something that’s really not there and my mind playing tricks on me. That wouldn’t make sense.

oh also pump leaked from the housing when we first turned it on, but a few tightening turns of the wrench on the 4 mounting bolts sealed the leak up immediately so I think it was just loose