Sorry you’re having algae troubles but follow the
SLAM Process article exactly & you’ll eradicate the problem.
Here’s a few pointers

For a successful SLAM Process
you need to continue to
MAINTAIN Slam level fc for your cya
FC/CYA Levels as often as possible until you meet
ALL 3 end of slam criteria-
You are done when:
CC is 0.5 or lower;
You pass an Overnight Chlorine Loss Test
AND
the water is clear.
(Crystal Clear w/no algae dead or alive)
*Check & scrub every nook & cranny where algae may hide (light niches, steps, drain covers, ladder handrails, skimmer throats/weirs, etc.)
*Run slam level water through all water features & lines for at least a couple hours a day during the
SLAM Process.
*Brush & or vac daily (this breaks up biofilms that algae uses to protect itself from chlorine)
*Backwash/clean filter when pressure rises 25%over clean pressure.
You will need a proper test kit to complete this task
See —>
Test Kits Compared
After all is complete be sure to maintain fc above minimum for your cya
at all times so algae never strikes your oasis again.