I bought a photometer "Exact Micro 7+" to measure PH, alkalinity and chlorine, but when I measure a sample that contains water from multiple points of the pool, the results are not the same as when I measure a sample from only one point of the pool. This photometer was originally build to take one sample from a particular point of the pool, but I want to know if I can trust more on the results from a sample of a bottle that contains mixed water of multiple points of the pool.
As long as there is proper circulation in the pool, it should test nearly the same from one spot to the next as long as there are no dead spots from lack of circulation. A sample bottle taken out should also measure very similarly to the rest of the pool. Be aware that the sample could also change after 30 minutes or more, so only a fresh sample should be used for comparison to the actual pool sample.