The pH is usually anywhere between 7-8 pH. The chemistry of the water being filtered determines the final pH, hence the reason for the range. A pH reading over 7 is considered alkaline.
We recommend using pH Test liquid like this: https://amzn.to/2WH9yBV.
Similar products for pH and Chlorine tests for swimming pools are also available in Walmart or Home Depot. Based on our experience, the pH test strips and Electronic pH meters do not provide accurate results. We do not recommend using them for pH testing.