I've had a 10 gallon fuge on my 72 gallon bow front for 8 years and it does fine. I put a plexiglass divider wall in it with a deep sand bed, mangroves and chaeto on one side and a U tube siphon tube on the other to return it to the sump. I have it lit with a simple 100 watt equivalent CFL bulb. It grows chaeto just fine and because of the lower spectrum, it also grows hair algae as well which is good because it doesn't grow in the tank at all.
IMO having your chaeto tumble is nice, but overrated. Just as long as you have it and keep it thinned out as it grows, you will be fine. Mine doesn't tumble but it still grows.