[kien]

Being in Yellowknife your house must be fairly sealed up for a good portion of the year. Curious, what form of ventilation do you have? This is yet another variable that is different from some other people. Not too many reefers in Yellowknife I dont think. There is typically a major in house CO2 spike during the winter months especially for cold weather climates. The skimmer could have been keeping O2 and CO2 in the tank in a fragile balance, but once it was gone, the scale tipped in the wrong direction.

Sure, a lot of people can get away with not using a skimmer or not having to point their powerheads at the surface, but those same people may not have the same environmental challenges that your tank might be faced with being in Yellowknife. Again, there are so many variables from one tank to the other that you can't always say, "hey, well, Fred over there has the exact same tank as me and he doesn't use a skimmer, so I'll be perfectly fine without one too". "And hey, Joe over there doesn't point his power heads at the water surface, so why should I??" We all know the hobby doesn't work that way. It may very well be that your tank needs more aggressive oxygenation and gas exhaust than other tanks.