Reef Tank issue, understanding ATI ICP Test Results

[Exus]

This is a reef display tank at my restaurant. We've been having a LFS do bi-weekly servicing on this tank for a number of years now, but recently, after their servicing, we've noticed fish dying left and right. The LFS says nothing was wrong and wouldn't do anything about it, so I decided to do a ATI ICP test. Here are the results. I've only just started to study reef aquariums due to this incident, so I don't exactly know where to look for issues. Can you guys help me understand? What could be killing our fish and making our soft corals close up?

We've corrected the salinity and dKH to around 35ppm and 8dKH since that was something we noticed from using testing kits.

This is the results we got today from water we sent in 2 weeks ago, we've been doing water changes every few days since we didn't know what is wrong with water until now. We have an RO-DI system for water top-offs.

 

[MnFish1]

Can you give a little more information? how big is the tank?
What is in the tank?
Has any other fish, etc been added before the deaths?
Is it possible someone (a customer) - put something into the tank (this happened recently at an LFS near us)?
Any other changes?
Any Coral?

As to the test - did you verify the salinity and DKH in the tank (i.e. was it the same) as the ICP test? - ICP tests do not directly measure these things.

Second - your phosphorous (again - not sure how they are measuring phosphate with an ICP test) - is high. It seems to me the rest should not cause fish to die left and right - unless they did not prepare their last water correctly?

Third - what maintenance are you paying for? Because a tank with a salinity of 28 and an alkalinity of 5.4 is not being maintained that 'well'. Alkalinity acts to prevent swings in pH - and yours is low - meaning some problem could be magnified (i.e. a fish death, causing ammonia, etc and then a cascade of deaths. Do you happen to know your pH, and other chemicals that are done with your test kit (not the ICP)? Your maintainence company shoudl have records (if they are maintaining the tank). A salinity of 28 - equates to 1.021 specific gravity - which is really not a problem for a fish only system.

 

[Exus]

Can you give a little more information? how big is the tank?
120 Gallon Tank, with substrate and rocks, may be closer to 90 Gallon.

What is in the tank?
A variety of leather corals. Before adding new fish, only a lone clownfish survived.


Has any other fish, etc been added before the deaths?
No.

Is it possible someone (a customer) - put something into the tank (this happened recently at an LFS near us)?
The tank is right by the front desk, so it's unlikely someone would put something in there without us noticing. It's also fairly tall, so kids wouldn't be able to reach the top.


Any other changes?
No

Any Coral?
A variety of leather corals.

Last week, after a number of water changes and all standard water tests came out normal and after using a carbon filter for a week, I put in 10 new fish, 7 of which died since. The fish were fairly small, around 1 to 2 inches.

I'll do another round of water tests later today and will post results here.

I'll try to address the phosphate and phosphorus issue, but is there anything else I should look at?

 

[Exus]

My test kit results from today:
pH 8.0
Ammonia 0 ppm
Nitrite 0 ppm
Nitrate 0 ppm (probably because of how few fish I now have relative to tank size)
Calcium 380
dKH 7
Phosphate 0.25-0.5 ppm
Salinity 35 ppm

This was right after a water change, so I plan to check pH and dKH again tomorrow, before using buffers.