Pool store PH levels are significantly higher than mine!

[tsunami]

I tested my water on Wednesday at a PH of 7.8 and added acid to lower it to around 7.6. On Saturday, I'm expecting it to be around 7.8 again and took a water sample to a local pool store that I trust, mainly to test the CYA level, since I ran out of reagent(mistakenly dumped it out, AGAIN).

The pool store tested my ph at 8.2. All other chemicals tested seemed consistent with mine. I couldn't believe that my PH was so high, so when I got home, tested it at 7.7! How could it be so far off? I wasn't watching him too closely as he did the test, but remember him showing me how pink the sample was. My sample at home was light pink. I remember this happening the last time I took a sample to the store.

I'm using the Taylor test kit that comes in the TF-100 test kit, but I'm not sure what type the store uses, although I know it's a drop test kit with a bigger, plastic container with 4 seperate columns for water. Does anyone else experience that same inconsistencies? Could his test kit be more accurate than mine? I can see maybe a .2 difference, but a .5 I just can't see.

 

[Bama Rambler]

There are a lot of reasons for their results to be different. Age of sample, condition of the PS reagents, not cleaning the test block well, etc.

 

[duraleigh]

Based strictly on anecdotal evidence from the forum, i would say there is a greater than 90% chance your test is the correct one.

 

[Richard320]

pH does tend to rise with the sample sitting. I could see the sample bottle getting jostled a bit on the ride, aerating it on a small scale.

But I wouldn't trust their reading anyway, and I'd trust the CYA one even less.

Tell us, what did they try to sell you to correct things?

 

[tsunami]

There are a lot of reasons for their results to be different. Age of sample, condition of the PS reagents, not cleaning the test block well, etc.

I would think that his reagents would be "fresher" than mine, since he probably runs more tests than I do. But mine's about 10 months old and I always keep it clean and in a cool area. So, I don't think there'd be any issue with my reagents as of yet. But what concerns me is that .5 could take you out of range in either direction, it seems too significant.

Based strictly on anecdotal evidence from the forum, i would say there is a greater than 90% chance your test is the correct one.

Me too! :-D So I'm adjusting the water according to my calcs. But by any chance, could he have a more accurate tester than I do?

 

[zea3]

Did you test in sunlight? Most store have fluorescent lights and I think that may account for some of the difference reading the colors.

 

[tsunami]

pH does tend to rise with the sample sitting. I could see the sample bottle getting jostled a bit on the ride, aerating it on a small scale.

But I wouldn't trust their reading anyway, and I'd trust the CYA one even less.

Tell us, what did they try to sell you to correct things?

:lol:

He didn't try to sell me a thing, just told me to make sure I get some acid in the pool soon, but gradually and not all at once. This guy's different. He's the owner and the only worker in the store, does all the testing, recommendations, and once he even showed me how to break down the Quad DE filter with a cross sectional filter he has in the store. He's never tried to push any chemicals on me, and has never said anything that would go against what I've been reading here on the forums, although he did tell me that my phosphates were high and I might want to treat for that.