The guy asking check for copper below you is the exact reason i said something. I asked for an expert and i got you…. shooting down an idea because it doesnt fit yours…. Arguing over a simple idea to which i asked him to do NOTHING to his tank. I didnt tell him to take drastic measures and simply brought up an idea. Just because you joined in 2014 id consider older members with more knowledge but trying to shut down an idea for no reason ruins your credibility.
As for tds, certain metals with negative side affect can ruin corals as i stated. There is also an absorption status, if you take only beneficial metals or anything that goes into tds and bump it to 1000 ppm it doesnt matter whether everything is in acceptable ranges, shrimp for some reason are overwhelmed and it created an environment where they cant live. Id imagine that all creates share a somewhat similar balance. Ya know like how us drinking to much water can kill us

too much of a good thing is almost aways bad whether you say so or not. So he can check his tds and ya know if could be through the roof or super low. He can also take away that some of that may be from magnets and can check those as well for an signsof rust. Remove it and see if things improve over time with water changes.
Anyways im done with this whole situation with you and i wish luck to the guy or gal with the tank.