mac1215,
I don't know how long your tanks been running, but with your parameters and the death of extremely hardy fish, I could only imagine the source as being the problem. Unfortunately, some suppliers still purchase cyanide caught fish without knowing it. This can almost guarantee death after being transfered 3 or 4 times. Ich is not a terminal disease. Fish don't die because of it. I can't say this often enough, but your dealing with salesman. Don't get suckered into impulse buying. Try researching more natural methods of filtration. Not just reef websites, but nature websites. Remember, there are no protein skimmers or UV filters in the ocean. If you went the algae filter route, you can easily attain stability with a 125.
'The mob is easily lead.'