Why portable water-quality monitors and fixed-point monitors sometimes read differently
March 15, 2010
ATI has issued a very helpful brief on the differences
between the results given by portable water-quality monitors for conditions like turbidity and dissolved oxygen, and their fixed-point counterparts. Due to a mental bias in favor of answers that appear precise, people often favor the answers from their portable monitors over the ones from their fixed-point monitors -- because the portable monitors tend to give faster response times and to change quickly while in service. But those quicker response times tend to be due to the thinner membranes used in portable monitors, and they fluctuate more because fixed-point monitors are generally designed to give stabilized, averaged readings over a period of time. Knowing the difference between the two types of readings can give the user a better appreciation for the proper application of each.
We can help you with water-quality monitors
for a wide range of applications, including dissolved oxygen
, and pH
. We also have portable monitors available
for many of the same parameters. Please feel free to contact us
with your questions.
last revised March 2010