Deformed leaves, edges curling down . Compared 2 ph pens- 0.5 difference.

Well, I mainly grow DWC, it’s been a few years since I was in soil. But if your ph is off then your soil will probably be off too. A flush would help I think but not if it’s at the wrong ph. Most tap water is around 6.5ph so if you cant trust your pen at the moment then maybe just flush with tap water to be safe. You can grab ph strips usually at a pet store that sells fish stuff, there pretty cheap if your stuck without a reliable way to ph your water. Any garden store or hardware store or department store that sells gardening stuff will usually have ph test strips/drops too.

Thanks a lot ! I was surprised both plants started to go wrong direction all of a sudden as I've been trying to be as careful as possible to avoid mistakes from 1st grow. I've been using drops on the first one, got a pen for second run.... and I've got issues I didn't have before. I have already ordered some drops, I'll get some stuff to calibrate and store pens soon. What should I do now? Flush with water ?

I had a similar thing happen not to long ago, get some ph calibration solution to calibrate your pens and some storage solution to store them. I use a backup liquid ph kit to verify my readings every week or so just to be safe as well. It doesn’t rely on any calibration to give you a reading, only problem is if your colour blind like me then you will need to get someone else to verify the readings. Lol I have something like 5 PH testers now, but I really only trust 1 of them, the one I took care of...lol The others are all just cheap pens and if they are not stored in the proper solutions all the time they will eventually fail on you. So if you have 2 pens and your calibrating one off the other and your not storing them correctly then there eventually gonna get way outa whack. So if you got older pens and was not storing them in storage solution your probes are probably not the best on them as it is, so I would invest in some calibration solution, storage solution, and a decent meter if yours are older cheaper ones. And a liquid test kit if you wanna have the extra price of mind. Cheers💨