Maybe I found our leak (pic) Help!!

[matt4x4]

Hi Andie,
I gather it's an IG pool, not sure if that's been asked.
If your main drain is plugged successfully and you suspect the filter to be the cause of the leaking, then with your equipment off, you would not get any drop in water level on an IG pool.
If it's an AG pool however, you would get a drop in level, one way to test that is to shut off flow through the system, either by turning the shutoffs (if you have some) off or by plugging the skimmer and return. If the level continues to drop, it is not your equipment.

Somehow, I feel your problem does lie with the so called "main drain" that is supposedly plugged off.

[AndieP]

It is an old IG pool....23,000 concrete/plaster. We are losing water both with the pump on and off but we lose more with the pump running. Last night (over about 8 1/2 hrs) we lost about an inch and half. The skimmer was intermittently sucking air this morning

Would plugging the return jet and skimmer and turning the pump off and measuring water loss tell anything? I haven't done that yet. I am beginning to think that the filter is not the problem. I am getting very discouraged. And on top of that I'm having trouble getting the water to stay clear.

I guess I should just call a pool place to come out.

Again, thanks for everyone's help.

[opsman]

Before you go and call the pool place, plug each of the openings. I recall you have two, a skimmer and a return. I am still unclear as to what you have in the bottom. I suspect you have a main drain that may have been plugged because of a leak. Try to plug your lines off and see if the problem is there.