We took our kids on a Disney vacation and I left my sister some prepared food in tupperware for her to feed them on Sunday. This was last weekend. I fed the fish on Friday, no food Saturday, she fed Sunday, no food Monday then we came back on Tuesday. What I found is that the sunset hygro had algae near the tops and the tops seemed to be dead. The anacharis was covered in algae and the tops of my sunset hygro carpet were all covered in algae. Nitrite and ammonia at zero, nitrate between five and ten. Fifty five gallon with 2.5 wpg and dual DIY setup. Now, I noticed that the co2 was dead when I got back but I am at a loss to figure out what happened. I have since trimmed back all of the algae infested areas but am curious if you guys may have an idea of what could have gone wrong.