PH Results confusing

[mwalling]

Hello all!

i need some opinions as to what is going on.

For the last two weeks, each time I have tested PH levels with my Taylor 2006 kit, the reading has been 7.2 or close to it. Because it was significantly lower than the day (or two) before, I re-tested it. The re-test reading was 7.8. Strange, but I chalked it up to maybe putting in 4 drops instead of 5 or maybe the drops needed shaking before?? Same thing happened the next time I tested....same results. Tested a third time on the second go around to confirm the higher reading of 7.8 was correct and it was.

Same thing happened last last night when I tested! Any idea what I may be doing to get an initial low reading each time I test PH levels?

thanks for any insight!

 

[JoyfulNoise]

A couple of questions -

1. Are you rinsing the comparator block out both before and after testing?

2. Are you using the correct reagents (please verify the R-000# on the bottle)?

3. Are you dong the readings in natural outdoor lighting with a white or light colored background to hold the comparator up to (some people use a white sheet of paper or white siding).

4. Hold old is your bottle of reagent?

5. Do you add 5 drops, cap the comparator and gently invert two to three times to mix?

6. What is your FC level when you do the pH test?

There are few things that will interfere with the pH test aside from high FC. When I do the test, I start with the comparator block that was previously washed out after the last tests using tap water (sometimes I'll use distilled water to rinse out my gear). I then fill the comparator block with pool water, give it a few inverted shakes with the cap on and then discard the water. I then fill it with the sample I'm going to test and run the test protocol. The reason for the pre-rinse with pool water is to ensure that the tube is cleaned with water that is close to what I'm testing.

Also, check the age of your reagents. A few years back Taylor started to include Expiration Dates on their bottles as well as the usual lot numbers. If your bottle only has a lot number on it, then it is probably more than 3 years old and it should be discarded. The pH reagent is pretty stable but it does go bad and it is actually a mix of chemicals some of which are used to neutralize chlorine. So if the reagent goes bad and those chlorine neutralizers are not effective, that will definitely screw up the test results.

 

[mwalling]

A couple of questions -


There are few things that will interfere with the pH test aside from high FC. When I do the test, I start with the comparator block that was previously washed out after the last tests using tap water (sometimes I'll use distilled water to rinse out my gear). I then fill the comparator block with pool water, give it a few inverted shakes with the cap on and then discard the water. I then fill it with the sample I'm going to test and run the test protocol. The reason for the pre-rinse with pool water is to ensure that the tube is cleaned with water that is close to what I'm testing

.

Joyfullnoise,

Apparently it was a result of a contaminated tube of FC. When I started doing the PH test first, it gave correct readings. I have now started to be more careful in cleaning the test materials.

THANK YOU!!


Sent from my iPad using Tapatalk

 

[JoyfulNoise]

Good to know.

It's not often stressed a lot, but keeping the test kit gear clean is really important. Rinsing out containers before every use and when it's time to put it away is key. I worked in many different chemistry labs in my life so triple-washing chemical containers and glassware is an ingrained habit for me.


Sent from my iPhone using Tapatalk