Thanks Gene for posting the link. You could also check out my gallery where I have pics.
I run 2x36 watt PCs with one 10k bulb and one actinic.
As most of you probably know, smaller Tridacnas rely on feeding much more, and as they grow rely more on lighting to satisfy their needs. Regarding lighting, you must think of the amount of light energy the clam is receiving where it is placed. My maximas are inches from the PC light source, as opposed to feet in some metal halide tanks. I believe in the longrun MH lighting is ideal. I will be setting up my 180 for sps and clams within a year, but I believe my maximas would be fine for even longer than that under their current conditions. Therefore I believe it's acceptable to keep smaller clams in nanos with the intention of moving them when need requires. There are other issues beyond lighting in nanos that are necessary for keeping clams, and many people fail, only to blame it on improper lighting. I think that happens a lot in the whole hobby, when people lose corals they tend to jump the gun and blame lighting a lot, when in reality it could be many things. RTN in sps is another example.
Anyway I would only recommend keeping clams in nanos for experienced reefers. I feed heavily also. In my gallery also you'll see my refugium above. Hope that helps and feel free to question more if you like...
John