CBD Mexican Auto-flower second try

Hot dry week, so gave my plants an extra watering without nutrients. I saw these abnormal leaves (pictured) and then I looked up the possible problem the plant was dealing with. My pH has been between 6 and 7, so that may not be the cause. The other possible cause was listed as over watering. ???? During a week without rain. While I have been careful to test pH in my nutrient solutions, the author of one web page suggests that one should test the soil as well. I will purchase a soil test kit.