Mine seemed fine since its not close enough to get any turbulence or effect any of the light over it with the magnet. I just didn't know if it has any nutritional value.
When you clean your glass with a magnet it fills the water. At that point it goes in 1 hole and out the other. I was wondering if it had any value to the clam.
When I use my magnet cleaner it creates a cloud of powder which I imagine the clam could filter out; that being said I am skeptical that this provides any significant benefit to the clam. IMO good lighting, stable chemistry, and well fed fish should be all you need to have a happy tridacnid.