Button coral and Lobophyllia retracted

Question

Lobophyllia  

Button coral   Hi

I have button coral and Lobophyllia that have retracted.
They use to be open but suddenly they retracted.
I have no clue why.

I check the levels of MG, KH, CA, Nitrite and Phosphate every week and I am using dosing pump for KH and Mg.
I do water change monthly almost.

Here is the levels in my aquarium

Phosphate 0,25mg/L
Nitrite: 0,5mg/L
KH 7,7 dKH
Mg 1410 ppm
Ca 500 ppm
Salinity 1,025
Temperature 25c
Good water circulation
I use active carbon + de*nitrate in the external filter (have no sump)

I am using LED light (http://www.aliexpress.com/item/120cm-48inch-4ft-programmable-controlled-led-reef)

My Aquarium is 350L = 92 US gal
2 years old.

I send some pictures of the aquarium.
I can only send 2 pictures.
Tell me if you want more pictures that show the placement of the corals in the aquarium.

Any idea?

Regards.

/Oualid

Answer
Hi Oualid:

From your description and images, it would be hard to form an exact cause as to what's happening in your aquarium. It seems that you're doing everything right in regard to maintaining a healthy aquarium.

My best guess is the Green Frogspawn Coral (Euphyllia paradivisa) that I noticed in the image with your button coral is to close in proximity to these corals, causing them stress. Frogspawn coral need plenty of room, and should be placed far away from other corals.

I wish you luck with all of your future saltwater aquarium endeavors.

Regards,
David