I’m new to growing. First timer here. I noticed that 1 of my 4 plants have some weird looking leaves at the bottom. I’m only 4 weeks into VEG. I had a little rough start but with some help from my local store I think I’m back on track and this happens. I looked on all the leaves (top and bottom) and couldn’t find any traces of bugs anywhere. The symptoms look like mites. Could this be something else? Like P.H fluctuation? I found out my pen was way off calibration and I was giving low ph water to them. I’m just not sure. Any kind of advice would be super appreciated. Thanks for reading.