Leather coral open, closed, open, closed

Hi all,

I bought a leather coral on the 6th December and it keeps opening and
closing a lot. Sometimes it is open for days and then closed for days
and at other times it is open during the day and closed at night. It has
shed a mucous type stuff a few times which sort of looks like when you
peel from sunburn. The corals that came on the live rock are all fine,
in fact they are spreading/growing well. Is this normal behaviour for a
leather coral?

I increased the water movement around it after it's 2nd week here which
made no difference and increased the metal hallide lighting by an hour a
day. It looks great when it opens.

My Calcium level is still at 600 and my tank is only a few months old.
All other tests are normal, Ammonia, Nitrites and nitrates 0, Phosphates
0, SG 1.023 and pH is 8.4. Temps here in Oz have been hotter than normal
but until a couple of days ago the tank never got over 29°c and then it
just touched on 30 for one day. The first few weeks I had it the temps
were around 26/27C. I really don't want to spend $1000 on a chiller.

I only have a young pair of ocellaris clowns, a pair of pyjama cardinals
and a coral beauty in a 700 litre tank along with a coral banded shrimp
and an unidentified crab.

Is there something I should be doing or is this normal behaviour (or
normal behaviour for a newly moved coral)?

Thanks for any advice.
miskairal