Base is formulated using Potassium Hydroxide and Potassium Carbonate - pure plant nutrient. Add a little at a time if your nutrient pH is too low and this will raise the pH to within range. pH refers to the acid content of the nutrient solution. For plants to be able to grow best it is important that the nutrient pH be slightly acidic - the range of 5.5 to 6.5 is considered ideal for most crops. Generally pH will be fine and won't require adjustment when our nutrient products are used since our formulas are "pH buffered". However there are some important exceptions., when poor quality water is used to mix nutrient solution, when pH unstable media is used such as many rockwool and gravel products and when plant growth rates are so high that the nutrient mix is thrown off due to rapid nutrient absorption by the crop.