Air In Lines

[mikepell1966]

I admit it, I'm new at pools. I have been in the HVAC/Plumbing trade my entire life so I think I have the basics. First of all I am fairly confident I don't have a leak, as water loss has never been an issue. When my runs, water level in pump is always full, except for a "hiccup" every once and a while. If I'm watching the pump, I notice the water level drop slightly in the sump area, then come right back up. If your at or near the pool, you can see or hear an air bubble come out op the pool supply outlet on the wall. Everyone says leak, but if I don't loose water, where's the leak. On boilers, you have air scoops in the system. Sometimes instead of relieving air in the system, they are faulty and don't leak but siphon air in. I know a pool doesn't have the same thing, but where is this air coming from?