Looks like cyanobacteria (red slime algae) to me. Check your water parameters, get your nitrates and phosphates as close to zero as possible, increase the water current and circulation in your tank, and if you're overfeeding, cut back.
nitrates are 0, phosphates are at 1.0 ppm, which they have been for a while. flow is decent. could use another good powerhead. i have a canister filter that pumps 185gph and one powerhead that makes 190. maybe the cyano will choke out some of the hair algae:D
i almost forgot. my ph had crashed in the last week. it went from 8.3 to 7.8 since i tested last weekend. do you think the lower ph may have allowed the growth? i also had to add calcium last weekend for the first time since my tank has been set up. do you think the calcium additive could have lowered my ph? i am using seachem reef advantage calcium.
Reef Advantage will lower your calcium.When I was having to add calcium to my 30,I would have add buffer to bring the PH back up.
AS for low PH causing cyno,it is a possiblity.