I got black stains when we opened pool.I think fertilizer got in the pool.How can I remove it?Thanks

ajw22

Gold Supporter
TFP Guide
Jul 21, 2013
18,093
Northern NJ
Try vitamin C (ascorbic acid) on it. Most fertilizer blends have iron compounds in them as a micronutrient.

CVS or Walgreens or grocery store - Vitamin C tablets (1000mg per tablet....skip the rose hip flavored one ;) ). Crush up a bunch, put it in a nylon and let it sit on the spot. If it’s iron, it will lighten up