If the pH level of your water is between 6.0 – 6.9, you only need calcite in your neutralizer. For pH levels of your water between 5.5 - 6.0, you’ll need a 2.5 acid neutralizer with calcite. And for pH levels below 5.5, you’ll need a 2.5 acid neutralizer with a FloMag (Corsex) and calcite mixture.