False pH tests

Hi, I'm new here and have a Taylor K-2006 test kit and use the BBB method, sanitizing with 12.5% chlorine. I love how easy this is and my pool water is sparkly and clear. I do wonder about something. I have a perplexing problem with testing pH. I rinse the sample bottle with pool water and then test pH. Test 1 was 7.2. I immediately did the test with more water from the sample bottle and it was 7.6. I test a 3rd time and it came out closer to 7.6. For the past week I have been testing twice and the first test is always lower than the 2nd test. Which do I believe?

Are you rinsing the block out with pool water between each test? Or is some of the water/reagent from the first test still in the block when you begin the second test?

I'll be interested in seeing what some of our chemists say about your question....

Janet

Janet,
Thank you for your response. I rinse out the testing tube with pool water and make sure that all residue from the first test is rinsed away.

Haven't heard of that before. Try this:

1. get a gallon jug of distilled water from Walmart (abt $1)
2. rinse BOTH your test cell AND your sample bottle with distilled, then empty.
3. refill BOTH full with distilled, then let them sit for 30 minutes or so.
4. empty them, and IMMEDIATELY proceed with collecting and testing pool water.
5. do NOT cap or shake your sample bottle. test within 5 minutes of collecting.

Ben,
I followed your instructions and got consistent results between 2 tests, in fact, my results were 7.8 and just 2 hours ago, I got 7.6 dipping the test cell down deep into the water (after rinsing the test cell about 4 or 5 times). What does this mean? Does the test cell and sample bottle need to be cleaned in this manner occasionally?

You could have some slow-to-dissolve residue in the kit block. If you want, leave them both filled with distilled water after each use, for a couple of days, and they'll probably clean out OK.

Thank you so much for your help. I appreciate it very much!

You're welcome.