Was curious as to why only one polyp of my hammer coral extends. It’s in a low-ish flow area of the tank and I dim my lights for about 6 hours of the day and give them about 4 hours of brighter light.
When acclimating corals, its good to reduce your lighting when initially placing the corals and then bring the intensity up over the course of several weeks.
The last tank to which I added corals was a 40 breeder with a Hydra 32 on it. I reduces the light intensity to 50% and then increased it 10% weekly.