Please Help - - - - I think Im losing my corals

So my tank is 3 months old, and ever since I started adding corals, I've never really been quite satisfied with how they look. I've noticed that at first, my favia started slowly bleaching, and I just thought it as acclimating to my lights. But then I bought an acan colony, a chalice frag, an acro frag, and a zoa frag about 2 1/2 weeks ago, and they slowly became more unimpressive.

Two days ago, I noticed my acro frag was starting to bleach at the base. Seeing as acros are more difficult, I was thinking maybe RTN/STN. But then I come home tonight and it seems that overnight my chalice frag is almost half bleached!

Looking at the big picture, it just seems all my corals are either slowly bleaching or just not thriving. Even my torch coral, although plump and healthy appearing, has a head that appears bleached (while the other two heads look good, for now)

So here's my tank:

25 Gallon cube (18" square)
Reef Radiance DM-155 LED light (http://reefradiance.com/dm-155e.html)
10 Gallon sump with Chaeto
No skimmer

Here are the vitals:

Salinity - 1.025

Ammonia, nitrite, and nitrate - 0

Calcium - 320 (I know, low, will replace)

Alk - 4.5 meq/l

pH - 8.2 (taken just minutes after lights out)

Live stock

2 x True Perc Clowns
1 orange spotted goby
Emerald crab
Pistol Shrimp

I was running my lights originally at about 50% on both channels, but I emailed Reef Radiance and they recommended that I turn them down to about 30-40% and slowly bring it up.

So right now I'm running both channels at 30% with the lights hanging about 10"-12" above the waterline?

Part of me is thinking this is a lighting issue? I cant really think of anything else? Really kind of discouraged at this point.......Ive been way too patient for results like this : (

 

Here are some before ad after pics

Favia When I first got it and now:





Chalice then and now:





Acro then and now:

 

FWIW, the other livestock is fine................shrimp, crab, snails, and fish are all pretty happy..........

 

In thinking the alk/ca is quite imbalanced. What are you using for salt and how often do you do water changes? Dosing anything?

 

I use a DIY two part, salt is instant ocean. Was thinking of switching to reef crystals for the magnesium, but I wanted to get advice from here first.

But the alk is good right? It's just the calcium is low?

 

The alk is above the upper limit by a small amount. Do you use the two part ca/carbonate/magnesium? I think you should be ok with io or reef crystals. I use reef crystals and always have to add some mg. Ca and alk usually come out about right with rc.
Here are a couple articles that may help clear up the balance of the three:

http://www.reefkeeping.com/issues/2006-06/rhf/
http://www.advancedaquarist.com/2002/11/chemistry

I found the second article particularly helpful and I refer back to it frequently.

I'm not saying the is what's causing your corals problems, it's just the only thing I can see from the info

 

+1 to ^^^

Also, what is your phosphate level? High or low phosphates can be detrimental, especially for stony corals. Stunted growth and slow bleaching are prime indicators. A reading of 0.03 is optimal.

 

I would stop dosing two part. Water changes are enough for you at this juncture.

First, test your magnesium. If it's below 1350, get it to 1350.

next, I would bring alk below 4, closer to 3.5.

Lastky, I would get calcium above 400. I keep mine around 425.

 

I going to do a WC today and see if I can get the alk down. Ive never tested for phosphates, so I don't know what to say there.

Does anyone think this could be a lighting issue? Should I increase the intensity?

 

I don't. I think it's a water chemistry issue. Can you test your mag?