hey you did good acting early on the algae, we should kill it, restoring a no algae fine looking rock.
the alternative is a complete take over taking months to undo.
lift out the rock
take a kitchen knife and scrape it off roughly like a dentist scrapes plaque and we bleed a bit heh
scrape the algae off the rocks, avoiding other non target areas, this is why we use a knife and not some random dip. we are on-target gardeners in the bulletproof nano reef. there are less bulletproof ways to reef admittedly...but none will beat this cheat method that's a fact
after you have cheat scraped all the algae off the rocks and rinsed the areas in saltwater, dab peroxide from a bottle on the cleaned spot.
rinse it off again, saltwater only, and set the rock back.
that's how you cure rock from algae so that it doesn't take over. its not about messing with the water and then waiting to see what happens.
we do your sand later, work this one lets see outcome
there are 57 different ways to handle algae, this is the one I use because I can tell you when it will be fixed, how it will look after, and without fail that it will not have algae after that cleaning round. how fast it grows back ranges tank to tank. we're concerned with taking back current ground. growback planning is for the clean condition.