Sps bleaching?

[Reef_junkie91]

What would cause an sps to close up so much at night? I didn't think sps were suppose to show skeleton at night? Don't know what's going on but it has full polyp extension during the day and is growing. But this kinda worried me.

Salinity- 1.025
Temp 79-80
Ammonia- 0
Nitrite- 0
Nitrate- 10
Phosphate- 0.03
Magnesium- 1350
Alkalinity- 8.5
Calcium- 415

 

[Reef_junkie91]

Here is a picture of it at night. Something tells me that this is not right?