It looks like a heavy infestation of bubble algae. The tank has lost its balance with that much algae, you need to correct the algae situation and get the tank back in balance. Deal with the algae first, then make the corals happy.
Alk IMO is too high, and nutrients are too high, especially with all that algae if you still show high nutrients then the water is too nutrient rich. Toadstools like higher flow.