What is this junk?

[Pete polyp]

I thought it was dinoflagellates and have treated it as such with no luck. It's killed almost all fish, sps and snails in the tank. Hydrogen peroxide and chemiclean had no effect. Lights out for a week made it disappear just for it to come back the next time the lights are on. I'm currently using a uv sterilizer and it also seems to have no effect. Is it in fact dinoflagellate? It grew into a hairy mat on the glass and sand which I have cleaned up and don't have pictures of. There's also a little bit of cyano here and there, mostly growing on corals. It's not acting like any cyano I have seen before because it's not really spreading everywhere. Just on a couple of the corals. Zoanthid and lps (chalice specifically) don't seem bothered by it at all and are growing well actually. I'm about it pull out all my hair over this mess.

 

[KJ]

DIATOMS:

Diatoms are just a natural things that happens in a new aquarium and will normally will subside with in a few weeks to a couple months.


ID: This Algae normally forms on the sand, glass and rock work of a new tank. It has a variety of colors from a dark reddish color to tan, brown and green. On a lot of occasions there will be oxygen bubble's trapped in the algae from photosynthesis.

HOW TO CONTROL IT:
Medium to strong flow across the sand bed and rock, and watch the amounts of Silicate being added to the system ( top off water and water change purity is the main cause for silicate being introduced to the system )

NATURAL HERBIVORES:
Astrea snail, Turbo snail, Tangs, Trochus snail, Almost all blennies.

 

[Pete polyp]

It's not diatom. Diatoms don't grow into a mat 6"tall