Algae ID & help

[maron6977]

Tank is approx 6-7 months old . I have a few urchins and snails . This algae started approx 3-4 weeks ago and slowly getting worse .
Water did slip a little NO3 10ppm , NO4 .09
Also the feed line from cal reactor slowed down so Alk, Cal & Mag started to drop off . Trying to ramp everything back up .
I think ID would help me to remedy & hoping increasing mag would kill it off.