I have an IG 18x36 pool, hayward filter with hayward superpump. I have air bubbles constantly coming out of the jets into the pool. When I go out in the morning to turn the pump on after it has been off all night there is hardly any water in the skimmer. Could a bad gasket cause that to happen or could it be a crack in the pipes underground? I do lose a little bit of water everyday but haven't measured to see exactly how much. I also haven't done the bucket in the water trick to see if its evaporation but I'm thinking i'm losing a bit too much for it to be evaporating. If I put the valve to full port on either the main drain or the skimmer, I get air bubbles either way. I don't see any water leaking around the pump or filter.

The only gasket I've changed is the one on the skimmer lid and that didn't help. I haven't tried to change all the other gaskets yet. But, could a bad gasket cause the skimmer to lose water? I'm not looking forward to digging and/or pulling up concrete to see if its an underground pipe problem. Are there other tests I can try to see where air is getting in?