Can someone help me figure out why my pool pump does not prime without me doing certain things. Before I explain, this is what my pool looks like: ~18k gallon pool and spa with Pro-logic system, T-Cell 15 chlorinator, variable speed pump, DE filter, solar heater and gas heater, Clear 03 water purifier (UV doesn’t work), muriatic acid feeder, and dedicated suction side automatic floor vacuum. In addition, there’s a separate single speed pump for the water features. These were all installed by previous owners and I'm new to owning a pool. The DE filter recently had a complete cleaning and backwash. The pump basket and skimmer basket are clear of debris. So my system is set to start circulation in the morning but when the pump goes on, it does not prime (there is no flow) and the DE filter pressure is near zero. In order to get it to prime, I have to switch the Pro-Logic setting to spa and open the air pressure release valve on the DE filter until water starts to spout. Then I close the release valve (with pressure about 12ps) and change the Pro-Logic setting back to pool. It works fine the rest of the day. But the problem is I have to do that manually every day. I suspect air may be getting into the system but I’m not sure where or if that’s even the problem. Please help. Thank you.