Whats this?

This algae (I think) is popping up pretty quickly on my glass, like when I clean it, it's back a day or 2 later. Light brown in color, this is the best pic I could get of it. Can anybody tell me what it is/how to get rid of it?

Tank is: 90 gallon FOWLR, 30 gallon sump/fuge, fuge has 3" sand bed with LR/rubble/chaeto, skimmer. No sunlight hits the tank, I have two T5s, on antic and one white HO (not sure on temp, bought it used)

Thanks!

 

how long has the tank been up? livestock? lighting schedule?

 

Bought the tank used, it was set up live for 2+ years when I bought it. Tore it down, took everything including 95% of the water with me, and set it back up and kept everything alive. That was about 2+ weeks ago. So, previous owner had 2-3 years, I've had about 2-3 weeks. Lights are on 10 hrs/day. Fish and inverts seems happy.

 

Look like my back wall. I always thought they were pods, am I wrong? I hope mine (and yours) are!

 

im not sure because they are so small, but if you say its brown and its coming abck as quick as you wipe it and judging by the shape, im tempted to say its the start of a dinoflagellates bloom.

Can say for certain tho.