I have some ro/di water that I stored in my salt water mixing vat, approximately 15 gallons, which is loosely covered. It has been in the container for 3 weeks. I opened the container and it seems to have an oily or dirty residue on top of the water. Storage area in a closet off of laundry room/ furnace room.
Any ideas what it could be? Can it still be used safely?
Any ideas what it could be? Can it still be used safely?