Shrimp Baby

Ok so I had a Torch Coral head fall off today and is floating around. The main colony is doing fabulous and is much bigger then when purchased. I tend to not mess with things and am just letting him float around on the sand but now thinking I should try to place him somewhere where he doesn't float around. The colony did go through a sump change today and it went very well in fact took two hours max and everything was back up running. ALK - 9-10 dkh, Calcium - 600. PH - 8.1 And oh yes I know what you are going to say "Way to Much Calcium!" but what can I do? The city here dumps calcium in the water, even the local reef shops complain about it. The only thing I can think of is to do less water changes in hopes my corals and Crocea Clam use it up but then, well its less water changes. Not sure what to do about that. I test usually with two different kits to get the best idea of the levels as possible. I do not supplement calcium at all. Sometimes I will use Kalk to keep the levels stable and add Magnesium to the Auto Top off water. This seems to work great for the tank. I get lots of red and green coralline. My Montipora and Acropora is doing well and growing and both my fuzzy mushroom and green stripped mushroom have shrooms that left and are living and starting new colonies in the tank. Specs; 75 Gal, 20 gal long sump, Phosphate - 0, Nitrates - 0, Magnesium, 1280. I would appreciate any suggestions on the calcium levels and on what I should do with my floating Torch Coral. Other Inhabitants: One Powder Blue Tang Two Tomato Clowns Inhabiting a bubble tip anemone Two Bangai Cardinals Yellow Head Jawfish Diamond Goby One Fire Shrimp One Cleaner Shrimp Two Scarlett Shrimp Tiger Conch Leather Toadstool Coral Various Zoa Colt Coral Just joined so looking forward to talking shop! Thanks!