How old is your tank setup? I would get rid of hermits though. They destroyed my sps colony I had. They would all climb up on the sticks, look like a meeting of hermits. they would break the branches off, I still have some pieces scattered around my tank. I got rid of mine, they also need shells of different sizes for when they outgrow the ones they are in now, if not they will kill snails for there shells.
I just read somewhere on here that hammers do better with mag as high as 1500. Mine has been running at 1320 and is not doing as well as it should, had mine now for 6 years, started with 1 head now have a dozen. I am going to boost my mag to 1500 and see if it improves.