this simply didn't look like the Cyano that I've had in this tank before and with having diatoms and and then this I thought it might be Dino since there is no bright red or purple hue to this.
If it is Cyano then I know what the issue / cause is, the poor filtration design inherent with this tank.
And before you say anything about nutrients, they play their part. The tank is only fed every third day, 25 g of frozen mysis rinsed, the tank gets 30-40% WC weekly, and running the stock filter, chemipure blue, Purigen, along with a mesh bag of mixed gfo and rox. The sand is vacuumed every other week. (1/2 this week 1/2 next week and ect)
Newish PCs bulbs (replaced them dead on 6 months). I've even shop vaced the rear compartments and removed everything that was there and continue this once a month.
Stock wise has two clowns, a peppermint shrimp, emerald crab,urchin, Zoas,mushrooms, pipe organ, candy cane.
Water tests generally show nitrates around 8-10 and phosphate around 0-0.15.
And with no ability to install a skimmer with out compromising some system integrity, I feel it's better to allow a new larger tank with the appropriate filtration systems with new sand and some new rock to complete a cycle and move the fish, coral, and inverts to it.
I know what Cyano is caused by and how to deal with it, this didn't look like the Cyano I have dealt with before and looked like some thing completely different, hence the post.
This isn't the only tank in my charge, but it is the only tank I consitintly have issues with, that I attribute to not having sock/skimmer. Along with its significantly lower Water volume.
Edit: also 6 snails, no hermits.