ok, so i've been working on ridding this pool of green algae for 2 weeks and now i have black algae spots at the bottom. it's a plaster 11,000 gal. pool with a cartridge filter. i've kept it at shock level for a few days now, i also had to add stabilizer and baking soda to raise the alkalinity. i took som pics...
100_1311.JPG

100_1312.JPG

100_1313.JPG
thanks for the help