Hiya GongShow! Do you have any updated pics? The old pics you posted look like it is probably dinoflagellates (bacteria), and not diatoms (alga).
Your stocking choices are rather exuberant. Both of the tangs you chose (Sailfin and Hippo/Blue) will get much too large for your tank. You also have way too many fish that will get big. If you were to keep the fish you have in there now even a 180 would get cramped up!! Those two are very poor choices for a 90 gallon tank, they both get extremely large. The only tangs that should be kept in a 90 gallon tank (imeo) is a Yellow or Kole. Both stay small enough...even then only one tang in that tank!! The Foxface will also outgrow your 90. Your Blue Linckia starfish will also probably die as they don't survive well in captivity.
With the amount of large poo makers you have in there (Foxfaces and Tangs poo A LOT) this is likely the main reason you are suffering with the dinos.
I think if you rehome the two tangs and the Foxface, and let the tank settle down a bit you could be looking forward to a nicer looking tank in the New Year!
You could post up a new stock wishlist too if you would like some help choosing suitable fish.
This old list you posted is highly unsuitable:
Achilles tang (get too big, very challenging specie should only be attempted by advanced aquarists with a very large tank)
blue (gets too big)
or yellow tang
blue flasher Wrasse
pinstripe wrasse
Foxface Lo or One spot Fxface (too big)
Longnose Hawkfish
yellow Watchman Goby
Flame Angelfish
Emperor Angelfish (too big)
Copperband Butterflyfish (very challenging specie should only be attempted by advanced aquarist)
Mandarin (you would need more live rock)
maybe dwarf lionfish
two percula clownfish
Even if you took out all the fish I said would get too big for your tank, the remaining fish (not even including the CBB) would indeed fill a 90 to capacity.
Sorry to rain on your parade...
