The Autopilot APCEPH1 Digital pH Controller accurately and reliably measures and controls the pH of any water-based solution, including fish aquarium water and hydroponic nutrient mixtures. After selecting the desired pH setting from 5.0 to 8.0 pH, the pH controller measures the pH value of the solution and automatically adds pH up or down to change the liquid's pH to the selected level. The Autopilot Digital pH Controller includes a low voltage dosing pump, and both temperature and pH sensors. Features include a digital display, adjustable mixing time, adjustable dosing time, adjustable pH dead band, maximum number of dosing cycles, pH high and low limits, and a data logger which displays the minimum and maximum pH recorded. This Autopilot is the only pH controller with these features for this value.