Wow, that was stupid of me.

[digital-audiophile]

So I fed the tank last night around 8:00 as I do every night, and per usual I turn off my power heads so the fish can enjoy their meal.

Well without thinking I turned off the lights in the basement and headed up to upstairs. I go down at 6:00 this morning to peak in the tank and realize that I forgot to turn the powerheads back on.

The tank spent ~10 hours with only the return from the sump providing oxygen (I have it thriottled back to ~200G/hour) Eveything seems to be fine, and the fish that I can see in their sleeping spots look OK. The actinics come on at 10:00 so I'll get a better look then.