pH drift - What's wrong?

Begruntled

Active Member
I have Milwaukee MW-102 pH/Temp meter. While in storage solution, the probe reads roughly 5.00 to 5.40, drifts maybe 0.01. When I put in my water / fertilizer solution, it jumps to over 7, then settles down and the hour glass goes away. Then, it will slowly begin to rise, maybe 0.01 every 10 seconds or so. It might increase an entire digit or more. For example, if it settles at 5.60, it will sit there for a minute maybe, then start creeping higher. After a while goes by, it might read 6.80!

I've recalibrated the meter several times using 7.01 pH and 4.01 pH, but it still does the same thing.

What is going on? Which value do I believe? Have I somehow damaged my probe?

Thanks for any tips in advance.
 
What you are seeing is the acids in the water already reacting to the minerals that are in it. Unless you are measuring against a stable reference like your storage solution, this drift is normal and a precursor of what happens when you apply your fluids to your soil. pH measurements are always just a snapshot in time and are constantly drifting in soil and solutions that have no buffers to passively keep the pH within a certain range.

When I adjust the pH of my water, I use a 5gal bucket, because the more solution I am working with, the more buffer it provides itself. I then add my ph down to get it to 6.5 and then wait a day. This allows some of the chlorine product to evaporate (although this new stuff they use doesn't ever go away) and it allows the acid to react to the limestone that is prevalent in our local water. After this first day the pH will drift up several points, and I adjust it back down to 6.5, using much less pH down the second time.

Each time you do this, and wait a day, you will notice less drift, and a quicker bounce back to your target pH. This is because the acid is actually breaking down the limestone and making it go away.

So what can you do? Smoke a bowl and relax. You might be overthinking this. We actually want the pH to drift in our containers. We want it to start near the low end of the scale, and by the time we water again, we want it to have drifted to the high end. This is how we make sure that all of the nutrients are picked up and are able to be mobile enough to move into the plant... some nutrients need a lower pH than others to do this, and sweeping across the range each time is exactly what we want to happen. Just adjust your pH to the middle of the range before you water, and let it do its thing. If you are dealing with very hard water or a soil that drifts quickly, adjust to the bottom end of the scale, and again let it do its thing.
 
Thank you very much Emilya. Seems strange that it's still drifting like this even though it's been sitting a day. Will try again tomorrow to see if it settles at a higher starting point. Cheers! :)
 
Hey my ph does the same I use ----------- buckets with net pots and a couple air stones but on the day I make a new mix I don't even touch my ph it will read about 5.6-5.8 so I leave it next day in creeps up a bit I write everything down and see my plant actually eating my nutes as the days pass I use rain water with the Lucas formula works for me so I stuck with it but really if I wanted to I could leave my res changes go at least 9-10 days before I need to much ph adjuster so I do a res change anyway just my thought all is good like said we need ph to rise to get all nutes available i am not expert I just read a lot of info and try myself it's just puts luck my first grow is going aswell as it is anybody can do it there is so much info out there it's not an option to fail:thumb:
 
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