AquaChek's Biguanide test strips allow pool and spa owners to test their biguanide-based sanitation systems for total alkalinity, total pH, and also total biguanide levels of their pool or spa simply by inserting the test strip into the water for around 30 seconds, giving you accurate results that give a clear picture of the health of your pool or spa. It is recommended that you test your pool a minimum of once per week.