You had that clam for 2 1/2 years in a tank and there is barely any coraline on the shell? :scratchch
Yes, that is true. I've been using just 400 watt 10,000K bulbs without supplemental actinic lighting for many years. A couple of times a year, the clam shell get's scrubbed to remove the algae, mojano's and other critters that were resident on the shell. When I had the actinic lighting, there was alot more coralline on the shell. There is an MTC ProCal that I use to maintain the calcium for the 400+ gallon system.