"Hardness Plus & Alkalinity Plus
Super concentrated 2 part Calcium additive.
The NatuReef® Alkalinity Plus and Hardness Plus provide 9,500 mequ. of alkalinity and almost 200,000 mg of calcium hardness per gallon. Along with these major anions and cations are also chlorides, sodium, sulfates, borates, lithium, magnesium, bromides, fluorides, bicarbonates, strontium, potassium and barium. All the elements are in proportion so they will not alter the chemical ratios in seawater. Only a slight increase in salinity may be experienced if there is little skimmer effluent waste. "
May be ok, never used it, but most of these added goodies are already in your salt mix.
Calcium chloride, baking soda and magnesium are all you really need to supplement. And need to be measured and controlled to keep your levels consistent.