So during my regular weekly maintenance I noticed that the pump had a decent amount of air at the top. I went through some standard checks. I made sure the skimmer was clear, the water level was good. I tried to isolate the main drain and skimmer and the bubbles remain. I was afraid that I had a leak on the suction side (I’ve had it before with no loss of water in the pool.). My kids wanted to swim the following day and I turned on the heater. The next morning I noted that the heater wasn’t getting sufficient flow (and stated as FLO). The pressure gauge on my sand filter really didn’t move from the low end. From reading about the low flow to the heater made me try to backwash the filter. When I did it did come out dirty . After rinsing and returning to filter the air disappeared from the pump and now it fills completely. Could there be a reason why this happened ? Aside from me needing to look into my sand filter and pressure gauge any rationale for the air bubbles with a dirty sand filter?