The bigger the better... I think a 10g would be a bit small to fit everything in it but it would work. A 20g works well if there's room. You could buy a per-built one or build your own. I personally have always built my own.
You can still run the canister filter... just make sure you...
Yah, a while back I got sidetracked with life... lol... so I resigned as a moderator, thanks for noticing :). I like this place to much to take away from it by being an inactive mod. There is a great group of mods here still though.
They run off of a siphon... but there is a Airlifter Vacuum Pump that can be hooked up to help prevent siphon breaks. A pump is placed in the sump/refuge under the tank to push water back to the tank. The only way you get a flood is if the siphon is broke when the pump continues to run... it...
I know this is going to sound strange but try lowering your water level a bit. If you can get away from filtering the water before the refuge it would be better. Lowering the water level may make the bubbles surface before entering the refuge.
I don't see any reason it wouldn't work... but other manufacturers make 60" fixtures... or you could look into a canopy. I used to run 2-400w MHs w/ 2-110w VHOs over a 60" tank using a canopy.
A 55g with LR can handle a LOT more than a 12g. Meaning things such as molts will have little to no impact on the water quality. In addition the cleaners will be more abundant and should make short work of molts and anything else they can find to consume...
I'd test the water from the LFS. I agree with acrylic51 but that seems to me to be a dramatic difference... with the calcium being at 450ppm... unless there was an imbalance to begin with.
So you do not add anything?? how about water changes... what salt are you using?? Do you know the calcium and alkalinity readings of your newly mixed saltwater.