American Marine Pinpoint pH Monitor
Product Review (submitted on April 28, 2009):
For the Koi pond hobby a continuous reading (recommend AC adapter) ph meter is a must. The probe cord must be long enough and the display large enough to view easily. The probe should last long enough to give you a reliable reading and easy to recalibrate. All this in one simple device by American Marine. This is my third meter, previous units malfunctioned after a lightening strike and my daughters rabbit chewed on the power and probe cords. For the price hard to beat.