I've used it but it comes back, my nitrates and phosphates are high in this tank. It just isn't set up properly. I plan on tearing this tank down and setting up a 240 butmy basement isn't ready for it yet. I just don't want to tear this one down to set up a90 to tear that one down for a240 so i'm just dealing with it lol. This had ahob skimmer and that's about it. No sump, macro algae,etc.
I really never pay attention to the clam but was looking at it tonight and happened to notice the larger hole. It's mantle is huge and always out but thought I would all because someone else had a hole and their clam died not too long ago. I don't remember the exact details or pics but do remember the post
It was mine and that one had a hole in a spot were it shouldnt have. Your clam looks fine. Since you are dosing your tank and changing flow it may be stressing the calm. They say when the clam opens it mouth more it is stressed. It will subside when conditions get back to normal. Other than that it looks great.