Crushed coral is a great for raising your aquarium pH. We recommend using 1 pound of crushed coral per 10 gallons of water when mixed in with our substrate.
Bought a small bag a crushed coral for pH adjustment in my freshwater aquarium. This was the perfect size for pH adjusting a few aquarium. Did exactly what I wanted it to, and didn't significantly cloud up my aquarium. Only suggestion would be the option to buy it in a larger bag size to mix with a large batch of substrate.
I was having some issues with low PH and low KH during the last week of my fishless cycle. The staff at Reef Life helped with options and the crushed coral has helped increase the KH