Would appreciate it if someone can id this brown growth. New to reefing so not sure if it's dyno, diatoms or algae. 13.5 gallon cycled without lights using semi-cured live rock from a buddy and some live sand. The tank was cycled for 16 days using pure ammonia and Seachem Stability. Zero ammonia and nitrites with a reading of .25 nitrates when I added 2 clowfish 3 days ago at which point the lights were turned on, thanks.