I have done the same thing in taking it to two different stores. Sometimes they are way off on some things, and once in a while they are close. I would have loved to have seen what YOUR testing revealed at that time.
Pool Store Experiment Water Samples
- Thread starter Par4monkey
- Start date
I had CYA tested at 35. Dumped 4 lbs in, tested 3 days later, they told me it was 40. I just said thanks and walked out. 
jedigrover
Gold Supporter
- Sep 13, 2010
- 333
- Pool Size
- 21000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Hayward Aqua Rite (T-15)
It makes you wonder how fresh their reagents are.
Besides that, the great thing about doing the testing yourself is you can be reasonably certain the tests were done in a consistent manner from one to the other. Even if your results aren’t perfectly accurate, if they are consistent that is a lot better than randomness.
The only test I’ve ever had real trouble with was CH due to expired reagents. If you test often enough, you learn to spot when you get a “flyer” and investigate before buying $200 of calcium chloride and totally wrecking your water. I’ve never had a pool store pump the brakes and go “that doesn’t seem right.” Especially if it means they can sell you overpriced chemicals and magic potions (some of them with the word “magic” written right on the label).
Besides that, the great thing about doing the testing yourself is you can be reasonably certain the tests were done in a consistent manner from one to the other. Even if your results aren’t perfectly accurate, if they are consistent that is a lot better than randomness.
The only test I’ve ever had real trouble with was CH due to expired reagents. If you test often enough, you learn to spot when you get a “flyer” and investigate before buying $200 of calcium chloride and totally wrecking your water. I’ve never had a pool store pump the brakes and go “that doesn’t seem right.” Especially if it means they can sell you overpriced chemicals and magic potions (some of them with the word “magic” written right on the label).