[Cranky When Wet]

OK, now I'm getting a handle on the oxygen exchange question... Perhaps it really doesn't take much to keep a saltwater tank oxygenated. I was looking for known numbers but now that I think of it....

I run a 900 gallon Shubunkin pond in my back yard and every spring just plug in a not-too-fancy pump that only pushes 600gals per hour...

It is just enough to keep pond/filter circulating with water surface agitated ever so slightly and the water (thawed out, semi-stagnant, slop from last year) is always fresh n' fish ready in less than a day... hmmm... could it be thaaaat simple?

And yes, Calgary has extreme (can go as low as -40C) cold some days with fluctuations that boggle the mind during winter... I definitely would go for insulating sides of tank because of our wacky weather patterns but am no longer considering covering top of tank... even if my corals shrink in the cold LOL!

Sooooooo... that's good news for nano keepers... you don't need a monster gen' to keep things going... just have a good pile of batteries on hand and you're good to rock... or, roll a couple small waves sporadically!

Thanks everyone for sharing!

Bunny