Ph pen readings

[Hebrewdiver]

I have a ph pen that was purchased off Amazon, when I try to ph my nute solution with it by pouring a small amount into a glass I get a different reading if I use a clear glass than when I use a dark glass. Is this normal if so which should I use to pour my mixture into clear glass or dark glass cup. There is a significant difference.

 

[BeccaBuds]

That isn't normal for a pH probe. If you have some standard pH calibration solution, such as Hanna Instruments HI7007, check the pen with it to get a better idea what's going on.
Are both containers clean and free of contaminants? When using the clear cup, can you cover it with something to block light and see if the reading shifts?

 

[Hebrewdiver]

That isn't normal for a pH probe. If you have some standard pH calibration solution, such as Hanna Instruments HI7007, check the pen with it to get a better idea what's going on.
Are both containers clean and free of contaminants? When using the clear cup, can you cover it with something to block light and see if the reading shifts?

Greetings and thanks for the reply. Yes I did cover it with something to block the light and the reading up about a point. I’m going to take your suggestion and order some calibration fluid. I’ve been using AN mutes and everything was going great without ph-ing my nutes but after I started using the pen my girls seem to be burning up. Oh well so it goes with this hobby. And they say cannabis is not addictive, well I love growing MJ addicted to growing…lol

 

[BeccaBuds]

Wow, that is weird. If it's reacting to light there must be a photodiode in there, but that's odd, too. Usually pH probes use a glass membrane probe and measure astronomically high impedances. I've seen a lot of people have trouble with the cheap probes off eBay and Amazon. If you google "pH scale" you can see charts listing common fluids and their pH- you could use one of those for a reference to test your pen until you get the cal solution.

 

[SmokingWings]

I get a different reading if I use a clear glass than when I use a dark glass. Is this normal if so which should I use to pour my mixture into clear glass or dark glass cup. There is a significant difference.

If the clear glass is actual glass and the colored glass is plastic the first thing that comes to mind is that the plastic is off-gassing more chemicals than the clear one. Solvents are going to be a major problem with plastic debris whether it is in the ocean or in the top couple of inches of soil. Right after that willl be the micro and nano plastic particles that are constantly breaking off of plastic and are so small they are being found in water, food and even human blood.

everything was going great without ph-ing my nutes but after I started using the pen my girls seem to be burning up.

Sounds like you found the problem. It might be as simple as the water out of the tap is well within the range needed for optimum growing. Stop worrying testing the pH.