Spare pH Electrode for HI991404

Spare pH electrode for Hydroponics and greenhouses. Compatible with HI991401,HI991404, and HI991405. The amplifier for the pH electrode prevents interference from humidity and sources of electrical noise include circulating pumps, motors, and ballasts for grow lights. The polyethylenimine (PEI) protective body protects against most aggressive chemicals as seen in fertilizer solutions with high concentrations of phosphate and nitrate.