Guys I am having with one of my returns to pump number 2. I have one pump that takes water from pool and the attached spa and pushing it through the filter. Then another one that just has a pipe comming in and going back underground. I am fairly certain it has to do with the spa. I have to main returns in the pool and two more in the spa (each has 2 pipes under it). There is very little water comming into that second pump, comming in slowly but water is clear so i dont think there is a crack in the pipe? the pump comes on when i turn it on but there is hardly any water in it. I rarely used it in the past but was always full of water (usually just circulated it a few times in a season to keep algea from growing in it). any ides what it could be? clog or maybe air stuck in it? I can take picture of equipment if needed.