Brain coral

Hey guys, I have a brain coral (I think it's a pineapple brain coral). Usually it is out and has its tentacles out but for the last few days, it's been shut very tight. It's tentacles haven't come out in the last 2 days. Any cause for concern? I tested the water on Sunday and my parameters were

PH 8.4
Ammonia 0ppm
Nitrite 0ppm
Nitrate 20ppm
Temp: 80f

I did a 10% water change Sunday. I did see my salinity was low (1.021) but I got it back to 1.024 today.

He still has very bright colors under the actinic light. Picture attached (it's a little more orange than the picture shows). Some help would be great!

Thanks guys
Casey

ive noticed that with higher trates the brain corals i have tend to shrink like that, as far as its feeding tentacles go you dont have to worry, they get most of the food from the lights, 2 days isnt bad ive had mine be like that for a week but usually it comes back even bigger and more plump,

Yeah, I'd definitely try to lower your nitrates. You probably raised your salinity up too fast also.

+1 to both. the salt jump may have been a bit quick...

A phosphate test would also be worthwhile. It doesn't take much phosphates to start making corals sick. About 0.25 is too high according to Dr Shimek who is an invert specialist and a also hobbyist.