My cleaner shrimp died I don't know what happen I'm treating the tank with ick with a product called greenex and it says it doesn't have any copper in the medicined so I don't know what happened.
Iodine is used by Shrimps when shedding skin so as Screwloose has mentioned, if the tank is lacking in iodine then this might well have been a cause of the problem.
However, in this instance im still inclined to beleive it had something to do with the dosing of the tank that changed water permaters. This may well have caused the shrimp to try and shed its skin as they wll do this after a changing of water conditions. So maybe there is an indirect link here with iodine afterall
Calcium helps them develope a new strong shell but iodine actually helps the old skin seperate from the new soft skin when shedding. If there is a lack of iodine then the to shalles can stick whilst moulting and this will cause the shrimp to die during the moult