Fixed a leak at the pump this spring when I noticed small bubbles coming out of the return and now the pump basket has very little air in it. However, in the last 2 weeks or so we have been losing 1/2" a day but only when running. Bucket test proved not evaporation. I dye tested and the openings in the pool itself. No water coming out of backwash line. I replaced the spider gasket last summer. The only thing about the filter, is when I turn it off I can hear air entering from somewhere. Other than that, there is no standing water anywhere around the pool so no underground noticeable leak. Any suggestions greatly appreciated.