Yellowing edges

Any ideas why my bottom leaf turned this color? I recently used insecticide for a minor mite infection seems to be under control now. And I just watered today and put in only cal mag.

@GreenThumbing You canโ€™t tell right away from this photo. Take a photo of the whole plant. It seems very weak. How often do you water and fertilize it?

Itโ€™s still a small clone I just planted last Saturday 1-16-2021 and I watered it when I first moved it to its 3 gallon pot with happy frog soil in pot and flora series nutrient kit. I watered a second time on 1/20 with cal mag. I also had a few spider mites so I sprayed my plants with mammoth pest control, water and dawn soap. 2 days ago?

I have never encountered a tick. Maybe itโ€™s because of the tick treatment. I would advise you to treat the room from ticks where you grow. God forbid they start again. Guys who have encountered this can tell you something.

You mean mites?

@GreenThumbing Yes, I have never seen ticks on my plants. Watch the plant if it is one leaf and does not progress on the other then do not worry. And so the brown and yellowed edges of the leaves are a lack of potassium. But Iโ€™m not sure. Can someone tell me more precisely

You can see from this photo that the stem and leaves are purple. It is possible that there is a lack of phosphorus.Phosphorus is poorly absorbed when you often water the plant. When the soil is constantly moist at the beginning of the growth stage.