Corosex can be mixed with Calcite to treat waters with pH as low as 5.3. Upflow filters are recommended unless the water is under 5 grains hard. A minimum of 50% Calcite is recommended to prevent cementing. By neutralizing the free carbon dioxide in water, Corosex can correct red water conditions and render it to a non-corrosive condition. Corosex, being a reactive magnesium oxide, is used most effectively where pH correction is substantial or high flow conditions are in use. Corosex, being soluble to acidity, will have to be replenished periodically. Please note, under certain low flow conditions, Corosex may overcorrect and create a basic condition.Corosex can be effectively combined with Calcite to combine the high flow neutralization properties of Corosex, along with the slower reacting low flow properties of Calcite reducing potentially high basic properties due to overcorrection.