What you are saying makes perfect sense. What test kit are you using to get to 2ppm? That is the only thing I kinda struggle with as far as the measurement goes. There is little difference between the 5 and 0 ppm reading on my kit. And, my wife will not let me spend the bucks on a probe
I am really graspin at straws on this one. The only thing i can figure enviromentally is the nitrates. And, the only thing that appears to have been having an effect on the clam. Im wondering if it is a life stage thing... It is after all the biggest of all my clams. Perhaps it's needs have changed. I can't find any solid info. I have a maxima that's spots (you know the patchs of different colors in the mantle, i call em spots) has gone white. The rest is still as purple as ever that is why I think it's different then the squamosa situation it's far more difuse and faded over all.
It almost looks like colmunaris (sp) on freshies.... Im considering a fresh water dip and or antibiotics. Waiting to see what happens.