well frogspawn maybe, there not that difficult to keep but the clam...no, not unless you want to spend your money of a jewl of the sea that might and probably will die in such a small tank. MH, so what? Im keeping sps and clams under 8T5s (432ww) in my main reef tank BUT i am upgrading to 3 175ww MHs in the very near future, the lights at the moment are just enough and your MH is a small one at that... i have a little nano with a 75ww MH and i tried to keep sps unsucsesfully and i would say that clams are just as hard if not harder to keep healthy. Dont do it man... the water quality is just not stable enough... and dont take the thing about the lighting above my main tank the wrong way, its not enough light and im upgrading very soon.
Just my .1c