I've seen these spots many times. Very common on warmer pools, dirty filters, poor circulation, short pump run times...the reasons go on and on. It is what it is. Black spots with a squishy surface that will burst and turn green when you rub them with your finger. Unfortunately my fingers don't go three feet down into the pool and here in lies my problem. One of the pool gurus will call them diatoms and have a specific online course for treating this but I've already taken their advanced chemistry course and I don't think I'm up for throwing money at mickey mouse courses who's accreditations disappear after a few months only to be replaced by another unrecognized qualification. Bottom line is, I have about five pools which I see this regularly in and I need to compile a strong attack plan to be able to deal with the issue and be able to deal with my customers' concerns.
Any help from the usual suspects is always appreciated!
Any help from the usual suspects is always appreciated!