The Sutro tests three times per day every 8 hours at 7:00am, 3:00pm, and 11:00pm UTC. We test 3 times a day, as we're utilizing this data to build out machine learning so we can better predict water chemistry.
In the future, we may decrease the test frequency or even give users the ability to program it themselves, but for now - this helps us design and build a better product for you both from a readings and testing side to a recommendations side.