Raises pH  Increases KH to buffer pH Adds some hardness to water If you have softer water with low pH, KH, and GH and wish you could keep aquarium fish, shrimp, and snails that need higher pH, crushed coral is a gentle and safe way to buffer your water. Crushed coral dissolves continuously over time. The lower your pH is, the faster it dissolves. As the pH rises, it slows down how fast the coral dissolves. Crushed coral adds a bit of hardness to the water, and it significantly boosts KH which buffers pH from swinging. Crushed coral is a natural product and may be a little dusty when you first receive. To prevent cloudy water, pour a handful of crushed coral into a fish net and rinse it thoroughly under running water. Continue this process until all of the crushed coral has been rinsed, and then it is ready for use in your aquarium. We use 1 pound of crushed coral per 10 gallons of water when mixed in with our gravel. When using crushed coral as an aquarium substrate, we find that the crushed coral may need to be replaced every 1–2 years, depending on how low the pH of the tap water is. Regularly measure the pH and KH of your water using multi-test strips to monitor the water chemistry so you'll know when it's time to add more crushed coral. If using crushed coral in a filter, it will dissolve faster. This means you'll usually use smaller amounts, but replace it more frequently. Crushed coral used as filter media typically needs to be replaced after 1–3 months.