The patented square wave Resilite is a reliable and economical method of monitoring water quality via conductivity.The bright red or green visual output is easy to read. The monitoring is simple; the green light indicates the water conductivity is below the threshold value; the red light warns that it is above. The solid state circuitry utilizes a symmetrical square wave sampling voltage to eliminate plating and extend electrode life. The LED output and solid state circuitry will outlast conventional neon lamps by thousands of hours. The Resilite uses a wall transformer to convert 120 VAC to 9 VDC to ensure safer operation and longer life.