Stony coral: any coral that has a hard skeleton. The two types are sps (small polyp [mouth] stony) and lps (large polyp stony). SPS take a bit stronger light than lps, and a good skimmer: since they mainly eat light, very clear water is a must.
The other must for any stony coral, lps or sps, is calcium supplement. Your salt mix and water changes won't be enough. These corals sop up an amazing amount of calcium, and a smallish feeding hammer coral can suck the calcium out of your salt water literally overnight.
Kalk is literally calcium powder. The good thing is, a) it's real cheap and b) it self-measures. You dump a cup into your 5 gallon topoff reservoir---and stir it once. Water can only 'carry' so much of it, ie---only the 'right' amount WILL dissolve. The rest will form a white paste at the bottom. You have highly calciumed water, now, feeding into your tank. And if you have a tank that's in the 75 gallon range, this is all the calcium your corals can want. [Big reefs have to get aggressive and FORCE water to carry more, using a calcium reactor---but little reefs are just fine forever with kalk in a LIDDED topoff bucket. [Air makes a film on the kalk in the bucket].]
There's only one catch: you have to start with your salt water in good shape. 3 minerals have to be in balance to make this work. You test your tank's magnesium level first. Get it to 1300, first, and remember---you don't 'instantly' dose up to a level---wait several hours to retest, and if not enough, add more, wait several hours, retest---you get the picture. The next step, probably the next day: test alkalinity. Get it to 9.3 by stages. The third step, again, test your calcium. [never add calcium supplement and alkalinity buffer together: you get a snowstorm.] You want it at 420.
Once your tank is at these readings, put the kalk in your topoff bucket, be SURE your topoff pump is sitting on something to keep it out of the white paste at the bottom; also lid it (cut a notch for your pump cord and output hose: use foam rubber for a gasket) and let 'er rip. Check your water level in the bucket and always refill before the water runs out. When there's no more white paste in the bottom, add another lot of kalk. Test your magnesium level in your tank at least every 2 weeks, but don't worry about your alk and cal. Those CANNOT fall so long as you don't let that bucket run out of water and kalk--- And as long as your tank doesn't run below 1200 on magnesium. That's your 'safe' zone for magnesium---1300 to 1200.
When you finally goof and let your tank-magnesium run out or let your bucket run out of water, you have to test your tank water and get it back in shape, then re-set-up your topoff/kalk system and then go merrily back to your lazy occasional-testing, no-dosing ways.
I have a 32 gallon trashcan as my topoff bucket. I can leave town for a month and know that my corals are going to eat just fine, if my tank sitter just pours 3 buckets more ro/di water into the trashcan in the second week and drops food cubes into my tank for the fish.