fifteen year old 16 k gal gunnite pool S Louisiana no major problems over years since Katrina when had to empty / refill. have spots on pool floor which are not of black algae origin. Have submerged self long enough to scrap the spot surface and unlike upsetting b. algae spots the 1 inch diameter dark spots do not budge. Difficult to see from distance only when standing above in pool. Do these sound like permanent stains?
Stains on pool floor
- Thread starter 63john
- Start date
Rub a trichlor pucks on one for 5 or 10 minutes. Then rub or let a Vit C tablets on one for 15min to a few hours.
If trichlor works it is organic, if Vit C works it is metal.
If trichlor works it is organic, if Vit C works it is metal.
Could be rebar bleeding through. Sometimes when it is really close to surface you will start to see rust around spots. Many times it will just be black and continue to get larger over time