Hello all, Quick background. I inherited a 6 year old tank about 6 weeks ago, and everything has been moving along splendidly. I went on vacation for the past week, having left a sparkling clean tank, and came back to find: 1) Green/brown stringy algae all over the tank 2) Little white stringy fibers (is this algae also?) on my acropora. A few comments: 1) A few weeks ago, I increased my feeding from 2 feedings a day to 3, since the fish seemed to eat all the food. The person that previously owned the tank (my cousin) always did 2 feedings a day, and he always targeted 1 teaspoon per feeding. 2) I filled my Eheim feeder before I left on vacation (1 week ago). It is now nearly empty. It's always a challenge to adjust the opening to get the right amount of food. If you are off by a millimeter, it will bump a massive amount of food. That being said, the volume of the feeder is 100 mL, which is about 20 tsp. So it seems like the dosing was about right. (3 tsp per day x 7 days - 21 tsp). 3) I recently started dosing 2 part solution to raise the alkalinity of my tank (which is 5 dH without any dosing, and I've gotten it up to 8 dH). However, the baseline Ca2+ concentration is >500 ppm without adding anything, so my guess is that I'm increasing Ca2+ well over the ideal zone by using the 2 part additive. I'm not sure if that's a problem. Am I overfeeding? What other parameters do I need to look at to prevent the growth of this algae? And, of course, how do I get rid of it? Is the white stringy stuff on my acropora likely different from the other algae? How do I get rid of that? Thanks everyone. The green stuff on this rock is representative of most of what's in my tank. This white stringy stuff on my acropora looks different, but seems like it would be too much of a coincidence that it happened when the other algae showed up.