What is wrong
 

The problem - I am losing corals slowly but surely. I have lost 3 different montys a procilapora, blue tip stag, horn coral, and green digitata. They all seem to bleach out. I have a colt coral that turned dark purple and none of his polyps are out, not sure if he is dying. Other corals that seem to be fine are favia, bubble, frogspawn, xenia, zoos, and duncans. None of the corals were large, mostly frags.The fish all seem to do fine but my rose bubble tip has shriveled up and disappeared.

Water Parameters:
PH 8.0
Nitate 10
Nitrite 0.1
Ammonia 0
Alkalinity 100
Calcium 440
Phosphate 0.25
Magnesium 1220
Salinity 1.0245
Temp 78-81

I am using RO/DI for my top up and regular water changes, not dosing anything. Using an eco plus 633 skimmer and a phosban reactor.
Have two double ended 400 watt 14000K metal halides set 8 inches off surface for 7 hrs a day.
Circulation is 10 times through sump plus 22 times in display.
Cant seem to grow macros in the sump chaeto doesn't die but doesn't grow either, I used miracle mud at initial setup.
The tank is over a year old.
Does anything stand out that could be the cause.

Did you aclimate them to your lighting? Do you have UV sheilded glass for hqi. Maybe you fried them. Nitrates could be lower but no big deal.

If the bulbs weren't shielded wouldn't it be likely that the fish would be affected??

Just wondering...do you run carbon? Has your tank been like this from the get go or just recently?

are you sure about your Alkalinity ,100 seems wrong, what are you testing with ?

400W is a lot of light and if you're having bleaching problems that would certainly be my first guess too. Try moving your lights up further, moving some coral down more, perhaps cut back on your photoperiod and remember to slowly acclimate coral by starting it off low in the tank.

You're magnesium is also a little on the low side and your phosphate and nitrate are a little high. Detectable nitrite is also really toxic. I'm assuming you mean Alkalinity 10.0 dkh?

A picture is also worth a thousand words. Do you have one of your tank/setup that you could show us?

Parnold I think I know you, you've been to my place and bought a lot of those frags off of me a few months ago didnt you?

Alkalinity seems quite low. If the "100" alkilintiy is in mg/L.

Alkalinity is typically reported as mg/L as CaCO3 (Calcium Carbonate) by Hagen test kits. This can be converted into milliEquivalents per Liter (mEq/L) by dividing by 50.To convert mEq/L (milliequivalent per liter)to dKH multiply by 2.8. To recap the conversion for the three units is: 1 meq/l = 2.8 dKH = 50 ppm CaCO3

so your 100 mg/L divided by 50 = 2 mEq/L
2 mEg/L times 2.8 = 5.6 dKH....quite low, I would bring it up to at least 8 dKH or 145 mg/L and the sps should stop bleaching.

Probably means 100 ppm which is around 5.5dKH. I think that is a little low.

Nitrite should be 0 you have 0.1 which would explain stony coral not doing good.

What is wrong
 

My lights are Hamilton, came with glass shield, dont know if it is UV shield.
I do run carbon.
Alkalinity is 100 mg/L tested with Hagen
I did start corals off low moved them higher after a week, I will try raising my lights to 12 inches off surface and cut back to a six hour time.
I thought the magnesium might have been low. Using aquacraft Meerzsalt and have since heard it is low in mag, have also noticed the coraline is not growing so much which I read is a sign.
Whatcaneyedo - it is me. The frags I got from you were not the only ones I lost. After seeing your coral I am pretty sure it has nothing to do with the specimens.
Will try retesting the ones of concern
What would be the best way to raise the Alk and Mag?