Abstract: A liquid testing system includes a first well for receiving a sample to be tested, a first light, having a first wavelength, for illuminating the first well, and a second light, having a second wavelength, for illuminating the first well. The liquid testing system further includes a light control, coupled to the first light and the second light, for selecting one of the first light or the second light to illuminate the first well, a light detector receiving light passing into the first well, and a processor, coupled to the light control and the light detector, for determining a light characteristic of the sample over time.