Here are my thoughts as to why the algae got so bad in the frag area and was not present to speak of in the rest of the system. First of all, the small yellow tang that I had in this area disappeared shortly before the phosphate spike caused the Algae to start running rampant, and I don't think I had enough snails and other critters to handle the load. The main display has two tangs and a large angel that are constantly picking at the rocks.
Secondly, between my work schedule, a new baby, and my other hobby, I didn't get down to look at that section very often this fall. In fact the Phosphate spike probably went unnoticed for a couple of weeks as I got a little lax in my testing regimen. The lights on the frag tank are also on a reverse cycle of the display tank lights so I am almost never home or awake when they are on.
Finally, I discovered that there was a lot of detritus trapped under the piles of live rock in that section. I normally take everything out and clean that whole section out two or three times a year, but it had been a while since I had gotten it done.
All of this created "the perfect storm" in this section of the system IMO, and caused the situation that you saw above. A lot of if is my fault, and I shared this part of my journey so that hopefully it will encourage everyone to keep a diligent eye even when life gets busy. It could have been much worse.
Top downs to come later this afternoon.
