HQI for clams?
I don't think so,
Just MH and LED.
As for Meowzer, how big is that clam?
I don't think your light is doing anything for it. Ive been wrong before...but everything Ive read backs up my top statement. Clams under about 1.5" cant photosynthesize well and need to be fed nutrients, larger than 1.5" they feed off light from MH and LED...but Ive never heard of them feeding off HQI,VHO,T5's...anything else.