Everything is dying from some white film

[prisse67]

My tank is almost 5 years I’ve been growing coral and everything has been so healthy. Perimeters are in check, except the alkalinity Doser keeps messing up so it did drop to 5.5 but I slowly raised it to 7.8 now. This weird white stuff engulfed my brain coral. It wiped out my hairy mushrooms and is attacking my candy cane coral. My Trochus snails are dying and so are the bristle worms. The only things that don’t see to bothered are the fish and some zoas. I attached pics maybe someone has seen this.

 

[ISpeakForTheSeas]

Can you get some more pics under white lighting? ID'ing stuff like this can be really tough under blues.