I've been battling algae for some time (three weeks). The pool was merely cloudy upon opening. I shocked, and upon the pool clearing, I maintained an FC level of between 3-4 ppm. The problems started after a week straight of heavy wind and rain.
I've confirmed that the pH, alkalinity, and FC levels are properly held for eliminating algae (mustard algae, at that) based on my CYA level (45 ppm). I have tested once per hour from 7:00 am to 11:00 pm (I don't work during the summer) and adjusted as necessary. I brush four times per day, minimum. The pump and filter haven't stopped. I added DE to the filter thinking that it would help catch algae spores better than sand alone. Lights and steps have been removed and brushed at least once per day. Starting Monday of this week, I DOUBLED the amount of Chlorine recommended by the pool calculator, while maintaining my brushing regimen. Still, every morning, I see tan sand-like deposits on the bottom (not just in shady areas, but all over the pool). When I disturb these with a brush, they immediately explode into little brown cloud and leave a thinner, darker deposit that needs more vigorous scrubbing.
I've spent $300 on bleach and muriatic acid. I have not tried a phosphate remover as they are not available in my area, but I could order one if it would help.
Otherwise...at what point does it become acceptable to go nuclear? Thanks in advance for the help.