Blue star polyps and Xenia dying, but others are good. No clue

[leokan]

Here is my parameters change history:

I suspect corals stint each other so I just added activited carbon for few day and no improvement.

 

[Jake_the_reefer]

I've heard kenya trees chemical warfare can be nasty but I've never seen it that bad so I'm not sure. I've never ran carbon in my 20g and I have a very large Kenya tree near my other softies

 

[leokan]

I've heard kenya trees chemical warfare can be nasty but I've never seen it that bad so I'm not sure. I've never ran carbon in my 20g and I have a very large Kenya tree near my other softies

my Kenya tree is weak too, only until I changed water 3 days ago it become better. So I guess Kenya tree was the victim of something else.

 

[S&SReef]

Do you have urchins? Pencil urchins will eat it right up at the base.

 

[leokan]

Do you have urchins? Pencil urchins will eat it right up at the base.

Nope, I had before, but it dead.

 

[Pntbll687]

It is probably the lack of nutrients in the tank. From personal experience, I had xenia melt away when nitrates fell below 10ppm. From your chart, it looks like that is what is happening.

 

[tankstudy]

It's probably the prolonged exposure to low level amounts of ammonia. Some softies can handle the low presence of ammonia but if you leave them long enough in it, they'll melt. It looks like your ammonia has only recently hit zero.