HI981412 pH Dosing System for Nutrient Solutions and Irrigation Water HI981412 pH Dosing System is engineered for maintaining the pH of nutrient solutions and irrigation water. The pH of nutrient solution or irrigation water is critical for the successful propagation and growth of plants. Macro and micro nutrients as well as calcium and magnesium bloom boosters require the correct pH for absorption into the plants root system. The HI981412 was developed to be an inexpensive solution for the horticulturist to maintain the ideal pH at all times. Simply insert the probe and injection valve in-line with the recirculation pump and provide the chemical to be dosed.