What am i missing ?

[Stormhaven]

Trying to help a friend.
All Lps slow recession and death within two weeks .
Same for sps STN .
Potassium is low and so is mag .
He will be adjusting today .
No3 5
Salinity 1.025 double checked with two refractometer.
Tank has been running for six months.
No pickers of coral .

Lighting par on average 200-250 Hydra 26s.

Possible contaminants?
Icp didn't detect high levels of metals .
So I'm at a loss .
Any ideas.
Thanks Guys

 

[bluprntguy]

Alk?

 

[KrisReef]

Based on OP,
Water circulation, oxygenation, (low/zero Phosphorus ?)
PAR?
Top off method?

Hope these guesses help.

 

[Stormhaven]

Alk?

Steady 8.5 as nothing grows.

 

[JCOLE]

Calcium looks low as well. Is he dosing?

 

[Lonely reefer's]

What did he changed before this happened
Sometimes corals shows signs of stress later on

 

[Fishfinder]

PO4?