Tank crashing

[George]

At first glance at your parameters, ammonia at 0.25ppm is high. It's at a deadly level to some sensitive fish and inverts (including corals). A few dead SPS won't cause that high of ammonia. Do you have any other fish missing or dead?
A mass water change should be done if it hasn't been done already.

Originally Posted by apexifd

While I was on holiday, there were few sps colony those started dying. As soon as I am back I have done a 40% water change. Hoping that I will flush out whatever thats killing my sps. And I have also added tlf 150 running carbon.

Here's my parameter
Sg 1.024
NH3 0.25ppm
NO2 0.25ppm
NO3 10 ppm
Phosphate 0.07 pm
Kh 9
ca 440
Mg 1450

I am suspecting the higher nutrient level comes from dying sps and not having the skimmer running for 2 days(setting up a new one)

What else could cause my sps to die?? Btw it looks like brown jelly when they are losing their flesh.