Corals close at night

[Alma pets]

TANK RED SEA MAX 250
SPEC
sump 150lt
Ca 425
Ma 1480
Kh 11.8
temp 25
salinity0.025
No2- 0
No3- 0
NH3/4 - 0
pH 8.4
NOW: My corals are closing every night only to open up in day time is this normal? I do a 10% water change every two weeks as well changed my tank lights.
My pincushion was open but closed up over time. Its been 3 weeks since it has closed.

The fish are in excellent condition. I am only struggling with my live coral
:headwally:



WHAT AM I DOING WRONG? PLEASE HELP

[kevin21]

When the lights go out, corals that extend their polyps tend to retract them back in. Being photosynthetic, this is normal behavior. When the food source goes away, most corals tend to close up, and then re open again when the lights come back on.

[Raul R Badillo]

Um....do a little reading. Some corals will extend at night like fungia and scolys and others during the day

[Mark9]

Um....do a little reading. Some corals will extend at night like fungia and scolys and others during the day

+1.
My trumpets/cynaria extend at night, frogspawn/torches/softies sulk.
Depends on the coral.

[Tweaked]

yep most close up, but by the early morning time, you see some amazing sweeping from favia, dendros, sps, etc. Very cool time to peek at the tank.