don have problem than y ur fishes are sick then? yes, water changes might not help the fishes that are aldy seriously sick. But pls give those inhabitants that r still living a fresh living environment and replenish with required trace element. Coral will seems fine now, but it wont hold for long without replenish of trace element. If u accept others opinion and do it the way u wanted, then y still post in forum and seeking opinion and yet argue with others advices? Imagine u in a car, with all windows closed, ur buddies or whoever started to smoke non stop, will u suffocate and died slowly due to lack of oxygen and the toxic from the cig. that keep entering ur lungs by inhaling?