Years and years in the hobby and I finally came face to face with dinoflagellates (Dino). What a (insert expletive) mess this algae is.
How I tackled the problem 8)
I first noticed micro bubbles on the sand bed and some brown algae, so immediate reaction...panic. My parameters are spot on and I over test my systems weekly even though I can usually detect swings in chemistry by just looking.
After some research I self diagnosed the problem as dinoflagellates -thanks internet images-
First reaction race to marinescape and buy DinoX, second action kills the light source in my tank, turn off reactor and blackout aquarium for 3 days.
In the end, I didn't dose DinoX I just blacked out the aquarium. Lost 3 snails :-( , everyone else was fine including the corals.
I'll be using UV, blues and white varieties for a week and then will introduce reds and greens back into my spectrum to ensure the pest stays away.
DON'T GIVE UP WHEN FACED WITH DINO! ;)