I am a new pool owner (2 years, see details below). First year was fine. This year, gray blotchy stains have appeared esp at deep end but apparent throughout pool.
Water tested neg for copper and iron; have been adding Blue Stuff every week.
Stain expert recommended by the pool company diagnosed 2 problems: (1) manganese stains;
(2) "improper startup" leading to plaster not hydrating properly (I don't know what that means). Stain expert wants to do a 3-week treatment that he says will fix everything without draining the pool.
If I have manganese in my water, how would I know?
Is there an additive that chelates manganese?
What did I do wrong to cause "improper startup"?
And, does this proposed treatment make sense?