Seek candycanes advise on this he breeds clams. I have seen clams under t5. I have a clam that came from t5s and was under t5 with me for a short while. Its under mh now and is very happy. I have heard alot of people with why why not to use t5, sometimes its ok sometimes not. It depends on the clam its self, the water parameters, location, type of fixture. Candycane knows all the technical mumbojumbo as to lighting needs.