Blue Hornets losing green ring

[Tavero]

Hi,
I've bought these Blue Hornets a month ago. At first they we're really bright. Now I've observed that the characteristic green ring and skirt is getting duller and duller. On two polyps it isn't even visible anymore.
My Rainbow Incinerators also got duller but at least they kept all of their colors...for now
What can be the reason? Light? Water? Is there a way to get the colors back?

My water param

Ca 430
All 8.5
PO4 0.25
NO 3.0
Ph 8.4
Temp 24C

I am dosing PO4 and NO3 right now because I've lost several frags due to low nutrients.

 

[Absolutely Fish]

If you are dosing iodine be careful I’ve notice mine doing the same thing when I overdosed lugols

 

[Tavero]

If you are dosing iodine be careful I’ve notice mine doing the same thing when I overdosed lugols

I've stopped dosing iodine one year ago because i didn't have a testing kit and also couldn't see any benefit. I mean elemental iodine isn't even bioavailable.

It seems like i do have a decent amount of light. I never measured par, but after buying some streched out magicians they lost their long stalk and are now flush with the reef plug. Maybe putting the hornets into the shade?

 

[Grossman90]

Happens. It will come back.

 

[Absolutely Fish]

I've stopped dosing iodine one year ago because i didn't have a testing kit and also couldn't see any benefit. I mean elemental iodine isn't even bioavailable.

It seems like i do have a decent amount of light. I never measured par, but after buying some streched out magicians they lost their long stalk and are now flush with the reef plug. Maybe putting the hornets into the shade?

It decould be a lighting issue. Zoas can be very funny. I have some that do awesome then start to melt and others that we’re doing crappy start doing better. Could be a nutrient issue. When all else fail I always say do a few water changes.