I have used it in my larger tank with some success. I put some in my small tank to increase the kH, gH, and pH a little. My tank is cycled, but my water is mildly acidic (just under 7) and I have pretty much 0 kH, and my water is soft. Great combo huh. My questions: 1 - How long does it take before the crushed coral starts affecting the water parameters? I put roughly a hefty tablespoon into my 10 gallon. 2 - Since this has calcium carbonate in it a) will my inverts benefit from the additional calcium, and b) will the plants benefit at all? Or is there too small an amount in it?