Hello! I am a brand new salt water pool owner (in Canada) and trying to quickly get up to speed on how to manage a pool (and two busy little boys). I've had the pool about 1 month now and no major issues except for a very slow but increasing build up of this white/cream stain in a strip around almost the whole pool, right at the point the vertical walls starts to slope down or meet the floor. I have the water tested weekly at the pool store and the only continuing issue is high Ph (7.8) so I'm regularly putting in a PH- product but haven't gotten it below 7.6 yet. Chlorine levels are on the high side but good. Hardness was low and we added Calcium. Salt was low and we've added 6 bags of salt so far, 1 more to add.
If I try to scrub the stain in one spot for a long time, it seems to lighten slightly but I can't get much force using the pool brush from above the surface. I admit that while I've been vacuuming every week, I haven't been brushing the sides regularly. It's not slimy at all, maybe a bit gritter but mostly just feels the same as the rest of the liner.
They tested for metals in the last water test based on what I told them about this and it came back negative. Any ideas what I'm dealing with? I poured in a bottle of a scale remover around the edge yesterday but didn't do a thing (or do I need to wait longer?).
Thank you for any help!!20150821_142406.jpg