Instrument: pH Sensor
An instrument that measures the hydrogen ion activity in solutions.
The overall concentration of hydrogen ions is inversely related to its pH. The pH scale ranges from 0 to 14 and indicates whether acidic (more H+) or basic (less H+).
The pH (NBS) of the aquaria during all experiments was checked twice weekly using an Orion 3-star pH meter and calibrated electrode; the precision of replicate pH measurements was +/- 0.015 units.