Why are you using anything? I find that so many people do so much more work than is required to keep their fish. Fact is, most fish are captive bred in water than is much different than the lake water, so you shouldn't need to worry about matching it either. The only way I'd use anything is if my water came out extremely soft and at about 6.5 pH, or I was having an extremely hard time getting any cichlids to breed. I find it just gets in to too much testing and worrying about that (I've never used a test kit and have never had any problems breeding anything; WC mbuna and Aulonocara, Rhamphochromis, Cyprichromis, Paracyps, Cyathopharynx, Ophthalmotilapia, Callochromis, Synodontis - many fish that are considered 'delicate'). Best of luck with them, but I always advise against adding anything to your water on a regular basis (but like I said, if your water is very soft and acidic, I can see the benefits of using a buffer like crushed coral).