Fish in bad shape after adding corals and inverts

I recently obtained a fair collection of corals from a neighbor who is parting out his tank.  They were all in the same tank at his house and they all went into my tank that didn't have any corals in it, just a Green BTA that is hiding behind a big rock where I can't see it.

I have a tank that is about 26" deep (81 gallons) and for my fish and anemone I only had about 150 Watts of light using 2 T5 High output bulbs 1-50/50 and 1 full actinic and 2 36" regular T5 bulbs that give out yellow light (standard home depot bulbs).

One of the corals that my neighbor gave me is a good sized acropora frag and a large finger leather, which, as I understand, crave high intensity light, so the day after I acclimated the corals and they spent about a half day looking great in my, what I considered to be, low light, I had picked up a used 150W metal halide light to put over the part of the tank that had the more demanding corals.

That is when things started to go bad.  I was expecting that the corals would open up beautifully and bask in the bright light, but they didn't.  The acropora and the finger leather seemed to dislike the new light and promptly retracted all their little polyps.  A frog spawn that was looking great shriveled up and hid (hasn't come back out since), a small colony of poly's all closed up, and a candy cane coral promptly closed it's only polyp.  I kept an eye on the temp, which got up to the low 80's, but I usually keep it around 80-82, so I didn't think too much of it.  The next day, my lights came on together with the metal halide and ran for about half the day.  At that point the temp got up to over 86 and I started to freak out because my Flame Angel wouldn't eat anything and the corals didn't seem to be adjusting at all; the acropora and finger leather, which, as I understand it, should be loving the bright light, were looking really bad.  I checked with my neighbor to find out how long he had his fish under metal halides during the day to make sure I hadn't gone too long, and after he checked his timers, he found that his tank was under metal halides for about 9 hours a day.  I cut off the metal halides and dosed the tank with some melaleuca to help all of the inhabitants recover.  I also grabbed a bunch of ice packs from the freezer and did what I could to cool the water back down to below 82, which took about 1.5 hours.

My poor angel died last night shortly after midnight.  And now my wife sent me a text today telling me that my Yellow tang is looking a little rough: a little pectoral fin damage and what she said looks like a scar along his dorsal fin.

I tested my water last night before the angel died and the pH was just a little low and the ammonia was at 0.25, but otherwise everything was fine.  What is going on?  Why are my fish dying?  Everything seemed great until I added the metal halide light.

Of course you picked the very thing that I was a little suspicious of, but ignored because it looked like a plain old piece of glass. I had to take apart the fixture to get it in place since I had to squeeze it in a narrow spot in my hood. It only covers half my tank though, so why would that kill a fish that could move to a shady spot to protect itself?

I just found an anemone on the back side of a rock towards the front. It seems to be fine as it was on the shady side of the tank. I got a look at my tang myself and it isn't as bad as my wife made me believe. He isn't his normal gorgeous self, but he is healthy enough. He will definitely recover.

I'm thinking that I will give my tank a few days at least to recuperate before I turn the MH back on even now that I put the glass back on. So is the glass polarized or is the 1/8th inch of plate glass enough to reduce the uv exposure?

The tank they came from was about 4" deeper, but had 2 metal halides + T5's, so it should be comparable.  For now I am leaving the metal halide light off to let everyone recover for at least the next week.  I am also adjusting things to get the temperature down to 80-82 where I like it (having lived on a tropical coast for a while, I know that that is closer to the norm than 74-76 or 76-78), but with the metal halide, I might try to pull things down to 78-80 to give me a little more buffer room if things start to get out of hand.

I run my lights on a tropical day (12 hours of light), but I am planning on implementing the metal halide only during the middle 6 hours of the day (at most) to represent what would happen in the brightest part of the day.  I have already set up a schedule that will ramp me up to that by increasing the light by only 15 minutes per day to help my tank acclimate to it.

I realize that my big mistake here was that I didn't do enough research about metal halide lighting before I implemented it and so I didn't know anything about the UV protective properties of the glass.  I have already found a way to fit the glass on to the fixture in my "retro-fit" application.  I just don't think I want to turn the light back on until I get a fan to help vent the heat out of the hood and my poor little sunburned yellow tang heals up.