ph problems

[georges]

Hi Folks

Just did something very interesting...rechecked my PH.
I have been using ph strips and today because of some burning leaves, I decided to double check.
ph strips clearly 6.5 to 7
gh test kit 4
Who do you believe???
Do these things go bad?
Just tried again with new strip from a new package same result
Just tried gh kit again and still 4?

Thanks g

[Toker1]

Both methods are not as accurate as a $20 meter.
Time to run an experiment. What does each method read when you test plain tap water?

[DW2]

Howdy georges, I use a pH test strip instead of a meter or a testing solution. The meters have to be calibrated and adjusted (temperature and 'standard' checking solutions) and the test solutions can be difficult to interpret the results due to dyes in the nutriment and additive solutions, looking through the vial of test solution, the dyes can alter the color of the solution enough to give a false reading. A test strip does not retain as much of the dyes and makes an accurate reading easier. The test strips and comparison chart should be kept out of direct or strong light to keep them from fading.
If You want to test the different results, use distilled or deionized water (should test at 7.0 pH) and not tap water as it will have dissolved solids in it which will change the pH.

[DW2]

If one is testing or checking the results from either a meter, pH solution, or pH test strips, one must use a 'standard' solution with a known pH value (either distilled water or a known value solution such as a calibration solution) in order to see if the method being tested is giving a correct reading or not.
Meters have to be calibrated and checked periodically for their accuracy (hence, standard solutions). Every meter that I have used, whether a cheap or an expensive one, have failed or gave erratic readings after usage. The pH test strips give me reasonably accurate readings and are reliable enough for hydroponic grows.
To each his own!

[Toker1]

How were you storing the meter? I have used $3000 lab grade ones and $20 ones found online. Lol One thing all have in common...they all need to be cleaned with DI water and stored in the proper solution after usage. If not the bulb becomes coated and you get the results described in your post. That bulb should never be stored dry. I’m guessing that was the issue with the meter.
Read the last part...

http://www.just4growers.com/stream/hydroponic-growing-techniques/how-to-take-care-of-your-ph-meter.aspx

[DW2]

I followed the directions that came with the meters. One said to use distilled water and not D/I water (or R/O). another said to rinse and store in a standard solution (4.0 pH). All in all, I have been getting the results that I need with less hassle and cost by just using the narrow range (4.0 to 9.0 pH) test strips.