detailed clam/light question

I have a 56 gallon column which is 24 tall, just like a 90 gallon, but its not as long left to right. My hood has a single 175W MH, while I'm sure that's enough for lower end brown clams, would it be okay for a blue clam like a Troch? If 175 isnt enough should I go with 250 or 400 ? I have no supplemental actinic or anything, but I could add some T5ho white or blue but I dont see it making much difference with the MH being there.

 

i dont think that would be enough lighting. i think 250 would be your best bet. but im no expert on lighting for clams. what is a troch clam? never heard of that kind.