I have a black algae problem. It has been getting better but the black little spots (1/4) inch will not go away.
This is what I have done:
1. Shock to 50 FC
2. Brushed with stainless steel brush
3. Emptied 30% of water from pool.
4. Ran to pump 24 hours for two days.
I am getting very frustrated but what should I do? Should I shock back to 50FC?
The details about my pool: PLASTER 30K NONE SALT WATER POOL IN GROUND /PH 7.4 CYA 80 /CURRENT FC 25/ ESTIMATED WATER VOLUME IN POOL IS ABOUT 18K GALLONS.
I thank you so much for any advice,
George from Claremont California.