Don't make any decisions based upon what they tell you. I'm also a member of a pool keeping forum, and pool store testing is only marginally better than those test strips. We adamantly advise every pool owner to purchase their own test kit and perform their own testing.
Pool stores are often staffed by untrained seasonal workers, ie. teens. And they are not diligent about cleaning and calibrating their equipment. Those digital testers may look impressive, but if contaminated and uncalibrated, they are no match for the accuracy of a decent titration test kit.
As an interesting experiment, we often encourage folks to take the same sample to multiple stores and compare the results. It's wild what they come back with. Oh, and they always need to purchase a few hundred dollars worth of chemicals to dump in.
Our method relies upon off the shelf products (such as baking soda to raise alk) and accurate testing, only adding what can be measured and only as required. I keep a 30k inground pool with a saltwater chlorine generator crystal clear year round for around $300 in supplies. For any pool owners here, check it out at
www.troublefreepool.com.
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