I have clams in my 30 gal with 4xT5. So far they seem content...well opened with good mantle exposure. I had one in my tank with halides and it shrunk away to nothing..there are aptaisia in the tank and I wondered if they irritated it. Anyway when I got others I put them in the T5 tank. What are early signs of them not thriving? If they decline I could move them to the halide tank.
I agree that success is based on the test of time and 5 months isn't much time
They are laying down new rings of shell so I hope that is a good thing.