Long overdue update but wasn't going to add anything til I figured out the ulva situation.
Ended up cooking some KP aquatics rock for almost two months and took everything out, scrubbed the tank with vinegar, peroxide and ran all the equipment in a citric acid bath for hours. Rinsed it all in ro water in refilled the tank with fresh saltwater. Took maybe 4hrs from draining the tank and catching the fish to putting the fish back in and regluing corals. Very happy I went that route as 10 days later evertyhing is growing good and coralline is coming back on the rock after being in total darkness for months.
Tank looks pretty bare and need to add some more corals soon. Did pick up a small flame angel yesterday which I know will outgrow ther tank and is a risk but so far it eats like a pig and has stayed away from corals and if he goes rouge on the acans I'll live with it. Need to scrape the back glass and do a waterchange but wanted him to settle in so will update with pics by the weekend when the tanks all cleaned up.