It is a tricky problem:
With truly zero nitrate+phosphate, corals will starve.
As zero nitrate/phosphate levels rise, corals are happy, but so is Algae.
If you are nitrate limited (0 nitrate, but not 0 phosphate), you get Cyano problems.
So generally:
1: Lower phosphates with GFO/etc, so you are more phosphate limited than nitrate limited.
2: Lower all nutrients in general. Carbon dosing, water changes, etc. Many methods.
3: Manual removal of as much algae as you can.
4: Snails, hermits, and perhaps a lawnmower blenny as herbivores.
Yes, snails cannot keep up alone, but with 2+3+4, they should be able to.
With truly zero nitrate+phosphate, corals will starve.
As zero nitrate/phosphate levels rise, corals are happy, but so is Algae.
If you are nitrate limited (0 nitrate, but not 0 phosphate), you get Cyano problems.
So generally:
1: Lower phosphates with GFO/etc, so you are more phosphate limited than nitrate limited.
2: Lower all nutrients in general. Carbon dosing, water changes, etc. Many methods.
3: Manual removal of as much algae as you can.
4: Snails, hermits, and perhaps a lawnmower blenny as herbivores.
Yes, snails cannot keep up alone, but with 2+3+4, they should be able to.