Unresolved Everything is dying! Please help!!!

Everything in our 90 gallon tank is dying. We can't figure it out. Took water samples to the aquarium store for them to test and they can't find what is wrong either. I do water changes frequently. Feed the corals 4-6 times a week as recommended on the bottle, and still! It's really freaking us out to be losing so much and watch our money going down the drain... literally.

Things that are dying, and doesn't make sense cuz if it was a bacteria, wouldn't it just affect certain species, and not all?

Gorgonian (Dying)
Christmas tree coral (Completely dead)
Bubble coral (Doesn't open anymore, just makes really small bubbles)
Star polyps (Went from about 200 to about 50)
Red yuma mushrooms (Had about 10 on the rock, most are dead. about 3 left)
Purple yuma mushrooms (Starting to look like the red ones)
Green hammer coral (doesn't open fully anymore)

 

What kind of lights do you have and are the bulbs good? Also whats your tanks params. Mushrooms in general are pretty hardy so it must be something pretty serious going on for them to be dying.

 

If you feed 4-6 times a week, it is likely excess nutrients. How often do you do a water change? What did the LFS test for?

 

I have an 8 bulb t5 light set up. I don't know all the proper terms for them. Lights only stay on 8 hours a day.
What are tank params?

I use marine snow. Following the directions it says to feed every day. I usually skip a day.
I do a 10 gallon water change every other week.
They tested for ammonia, nitrate, salinity, and kh? Said everything was good.

 

We need to know the parameters such as Ca/Alk/Mag... Nitrates, SG.

Relying on the LFS to provide accurate values is a huge gamble.

Any images of the tank or affected corals would be of assist as well.

 

Might test copper just in case.

 

My LFS is a great place, but their test kits are AT LEAST 10 years old. Never trust a test you do run.... unless its a lab.

 

Said nitrate was 2, ammonia was 0, and salinity was great.

Photobucket for some reason wont let me post the pics right now, so here's the link to the page. It's the first 4

Fish Tank pictures by xbbox - Photobucket

 

The store here just opened up a few years ago, but the 2 that run/own the place have been in the fish scene and working with salt water tanks for quite a few years. Both pretty knowledgable. We talked to the 3 places around here before buying anything and the other two places just want to get you in, sell you something, then kick you out. This place here is great. Wont sell you anything if your tank isn't doing good or if they know something is sick in the store they won't sell it. They actually care about the customers.

 

It is a beautiful tank, that must be very frustrating.

When corals start to die and fish remain healthy the first thing to rule out is swings or issues with Ca/Mag/Alk.

I can not stress enough the importance if getting your own test kit and monitoring those levels.

What salt mix are you using and water source.