When I did a rip clean on my tank (13 gallons) I ended up getting a cheap dollar store serrated knife to scrape the algae off the rocks. Then I treated the spots with peroxide. My algae wasn't nearly as bad as this but my tank was dying. Corals looked sick and I was about to throw in the towel. Rip clean saved my tank from crashing.
This was 3 days after the rip clean.
All I did was:
* rinse the sandbed until crystal clear.
* scraped algae off with a dollar store knife and peroxide treated the spots I scraped.
* Cleaned the tank/equipment with vinegar and then rinse with RO water
* Put in brand new water
Now I have other issues right now but my corals for the most part are happy and I am upgrading to a different tank soon.
It's still a rats nest but I can get enjoyment out of it now.