Sorry to hear about all your troubles, it gets really hard to be in this hobby sometimes. When faced with a situation like yours I would determine everything that is different between frag tank and display. It's normal to make assumptions based on experience but don't, remove, inspect every piece that is not the same as your frag tank, carefully. With everything you have done, been thru it has to be something that is NOT the same as your frag tank, only thing that makes sense. Again, if any doubts or as a double check, swap the piece of equipment from your display to your frag tank and vice versa. If the problem moves, bingo! You found it. Good luck. P.S. Some very toxic metals may not be part of a Triton test but be in these new super magnets.