I've never heard of off-gasing. Is that something to do with residual chemicals decomposing in the water? It's made to be in fish tanks so I'd hope they took that kinda stuff into consideration but you never know. I do like the way the bubbler is set up to make the front wheel spin...
The tank is the wife's thing. She's got a few mollys, some neons, scum sucker (that's what I call him) and another couple that I can't remember. We're going to replace the clown loach that died a couple months ago once the water settles back down from the cleaning.