pH probe indicate 7.5~9.5 (low at night high at day), pH Paper indicate 7.5 (all time)
Hi guys. I’m new guy in Dev cop. which makes industrial IoT service (like gas, fluid leaking detection).
Recently I start project for pH sensor network.
I gather quite dirty water from backyard and put it in top floor for testing red tide photosynthesis and organism makes pH Higher.
It does change pH ( The probe shows When Night, it goes 7.4 and daytime it slowly spikes up to 9.5 ).
For make sure my test, I bought pH paper from TOYO Roshi Cop. and soak it in testing fluid
But pH paper doesn’t change its color at 9.5. Just green like it's 7.0
I’m electronic engineer so im quite dumb at chemicals.
Heres what I did to find reason.
1. Put salt and Sugar into dirty water for Ionic strength stronger. (It doesn’t work. I thought this is the reason why pH paper doesn’t dye)
2. Cover The pH probe and water with dark cloth for stop photosynthesis. ( pH probe keep shows 7.5 )
3. Soak Probe into buffer solution to testing sensors, and It was accurate. (Cleaned with Desalted water)
4. Use 4 different sensor ( Different model, code, measuring method and all shows pH is 9.5 )
I don’t have any clue