Smoothie/Cream Cookies Auto

It looks more like a Cal/Mag issue. When in flower the plants use a lot more Cal/Mag. The upper leaves and buds are stealing nutrients from your lower leaves. With autos it typically starts showing up in the leaves around week 6-7. The deficiency probably started back in week 4 when growth increased. Even though you have been adding Cal/Mag all along there may be an issue of soil ph causing lock out of the nutrients or a possible excess of another nutrient blocking absorption. There are certain proportions for calcium and magnesium that need to be used since excess of either micro nutrient can actually block out the other. Potassium 4 parts, Calcium 2 parts, Magnesium 1 part. I would suggest increasing your Cal/Mag dose to 2 ml per liter since this product contains nitrogen you need to account for this if using another nitrogen product in order to prevent nutrient burn. I also agree with Spinner about ph I woulds suggest using 5.8-6.2 for watering and feeding. If you have hard water even when you adjust the ph if you leave the mix sitting there for 1/2 hour you will see it "bounce back up" to a higher ph. This bounce happens more often than people think. Not sure if that is the case with your water supply. If your water is more than 200 ppm in TDS I would suggest using reverse osmosis or distilled water to dilute the tap water down or in half this will help you maintain a constant ph. Also when your plants are large enough to water the entire pot measure the runoff ph and PPM to give you a better idea what your dealing with.👍

https://www.amazon.com/HM-Resistant-Hydroponics-Gardening-Aquariums/dp/B01CP9Q192/ref=sr_1_82?qid=1570289955&s=industrial&sr=1-82 HM PH meter. I bought it from my local hydro shop at 50 bucks, 40 on Amazon, and found it holds its' accuracy pretty well. There is another waterproof model for more money. I used the older yellow/cheap ones from amazon and they are all over the place... This one I check every couple of days and it will normally raise .1 over 10-14 days. I use GH hydroponic solution (7.0) to check it... If you wanted you could leave the PH meter (the sensor) in the PH solution all the time, as you are supposed to keep the sensor wet. I tried it but ran out of solution pretty quick.. so I stopped doing that. happy growing! 👊