Please excuse my ignorance as I am a first time pool owner, having bought the house in March 2009 (the pool was installed in 1983). I've noticed that there seems to be a lot of air build-up in the filter, the pump basket is only completely full of water when running at very high speeds, and often (though not always) I'll see bubbles coming out of the inlets, ranging in size from tiny (i.e., Champagne sized) to ping pong ball. I can't see any other problems with the system but based on what I could glean from searching this forum, it doesn't seem like a good thing.

The pump is a new Intelliflo VF that I had installed in April due to concerns over operational costs. To be honest, I don't remember if I was having the same issue with the existing pump (I think so but am not 100% sure). The pump basically runs 24 hours a day at about 1600 RPM, which is enough to turn over my 19,500 gallon pool once a day. If I run the pump in vacuum mode, the much higher rate of flow will fill the pump basket with water as I would expect to see in a closed system (again, I'm new to all of this...). But after I switch back to the default rate, the water level in the pump basket will slowly drop down to around the top of the opening from the basket to the pump interior (it's possible that it goes even lower but I'm not sure).

There certainly seems to be a lot of air build up in the filter. If I check once a day, it'll take something like 10 - 15 seconds from when I open the manual air relief valve until I get a steady stream of water shooting out. Wait 3 minutes and try again, and there will be a lot of air hissing though the wait time before steady water is a lot shorter. I can also hear what sounds like air gurgling in the heater.

From what I've read, the culprit would appear to be some sort of suction side leak. But I have found absolutely no evidence of any sort of water coming out of any visually accessible components. I've lubed the seals on the basket cover and the filter dome without any sort of change. I've tried spraying water on the pump to see if there are any obvious entry points but I think it would be hard to know if water was indeed being sucked through some sort of opening. I can't hear any obvious hissing going on. Water loss in the pool seems to be about right given that I live in a very hot and windy environment and given that there is so much air built up and\or flowing into the pool that an undetectable underground leak seems unlikely (at least I hope so).

My questions:

1) Is this something I should be concerned about?

2) Is it normal for the water level in a pump basket to be only about a 1/3rd full when running a variable speed pump at a low speed?

3) What might be the likely entry points for air entering into this supposedly closed system?

4) What tests should I perform to figure out the extent and source of the problem?

Thanks for any help you can provide!

Nick

Palm Springs, California