Hammer Coral Concerns

Hello all, I have a hammer coral frag that I bought from a local reef store two weeks ago. I was kind of concerned because my hammer coral keeps on shriveling up and going back to being fully extended. This is a pattern that happens during the day and at night, however, at night it usually closes up. I don't know if I should be worried because the frag keeps on shriveling up from time to time.
The following water parameters are:
ammonia: 0
nitrate: 5
nitrite: 0
salinity: 1.024
temperature: 79 degrees fahrenheit
ph: 8.2
Salt type: Red Sea CoralPro Salt (contains needed calcium and magnesium for coral)
Tank mates: A Pair Of Clownfish, Skunk Cleaner Shrimp, and a Scarlet Hermit Crab. (No other coral)
Size: 10 Gallon Nano Reef

Any replies would be appreciated. Thanks! :thumbup: