Brown Hair Algae?

I have a problem with this hair algae that is growing on all surfaces and especially on the base rock where there is high current. I thought the stuff would grow were there was a lack of current.

The tank is 3 months old and the water parameters are great.

Ammonia-0
Nitrites-0
Nitrates-0
Ca-400
Alk-3.3
Kh- 9.3
Salifert test kits
No Phosphate test yet

I use RO/DI water and Instant Ocean salt and have the salinity at 1.025

I have 2 dozen Nassarius and 4 dozen Astrea snails, 2 Peppermint shrimp, 2 Emerald crabs and a dozen blue legged hermits.

The 2 tangs are eating the algae as well as the snails but they can't keep up with the growth.

I'm hoping this is just a new tank thing. Any ideas or suggestions?

I guess it isn't to the point of being really bad yet but I would like to not let it get out of control. I have been manually removing it and doing 10% water changes every week. Oh, I am dosing 2 caps a day of Kent Tech cb to maintain Calcium and Alk levels. No other additives and am feeding sinking pellets to the clowns once a day.