Eti 813 513 ph pal plus ph tester eti 813 513 p this ph tester from eti is a robust meter that can be used both indoors and outdoors courtesy of the water resistant case making it ideal for measuring the ph in food processing and water testing applications it is also an invaluable tool when mixing concentrates with water p p the meter is user friendly and incorporates an automatic recalibration feature at the touch of a button the instrument will automatically recalibrate itself when