Help identifying strange algae

[Baldy]

Hello all,

Maybe im missing something in all my reading, but i am having a hard time identifying this type of algae. At first i thought it was red HA, but im starting to doubt that now.

Its really strange. It seems to only form in the morning on the sand and rock low in the tank. its deep red, almost maroon in color. Ive tried moving flow around to get at the areas more, but it doesnt seem to help anything. The really strange thing is, that after a couple hours in the morning, it starts to disappear. its mostly gone by the evening, aqnd doesnt start forming again until the next morning. This has been going on for a while now and its driving me crazy.

All parameters are in check as far as i can tell. last tests were 2 days ago: ph 7.8, alk 8, mag 1250, calc 410, temp 78, sg 1.025, nitrates 0, phos 0.01 on my hannah checker. I have a 75 gal tank with a 20g sump, using a tunze DOC 9006 skimmer, running carbon and GFO. All i have for tank inhabitants are 2 clowns, foxface, matted filefish, flame hawkfish, and solar fairy wrasse.

any help?