Stain

So I have this white non moveable stain around the floor of my pool that is about 2 ft wide around the edge. Any ideas??? I have tried citrus acid( worked a bit)  I am attempting jacks magic stain test kit to see what type of stain it is.   Help!!! Oh and my phosphates were at 1000 also.

Test your water to see where your total alkalinity is at.  If it’s very high (above 170) it will cause white, sticky staining (especially along the edges or in the deep end).  If that is indeed the problem, add a half gallon of muriatic acid, let it mix in overnight, then aerate your water (ideally using a submersible pump or fountain feature, but you can also just have a bunch of kids splash around a lot).  Then keep repeating the process until your TA is under 100.  The aeration process is necessary to bring your pH back up because adding muriatic acid will bring both the TA down and the pH.  The white stain should start to recede slowly day by day.  It won’t happen all at once.  You can buy muriatic acid at Lowes or Home Depot for about $9, but wear gloves and goggles when handling it; it can damage your skin pretty easily.