The strontium is nothing to worry about. But that iodine -- wow. Not sure how to address aside from water changes (which would take care of the nickel, too). Any idea how the iodine got that high?
Triton cannot reveal what form it is, and iodine can be in many (iodide, iodate, and various organics, for example). So one cannot easily know how to reduce it, or if it is even needed.