Week 6 of flowering 10/23/24 Changed nutrients to fit week 6 Buds are getting even bigger and thicker. Defoliated a little. Noticed a PH of 4.8 in runoff, same as the late stage of flower in my previous grow. After lowering feed EC, CalMag on max strength, flushing with 0.8ec nutes for 3 days in a row, nothing changed and PH stayed the same. Read in a forum thread about constant low PH in the rootzone when growing in coco. Got great info about CEC, water, nutrients and little chemistry from a detailed explanation. (https://www.icmag.com/threads/recurring-problem-with-low-ph-in-coco.338385/page-2#post-10843765) Flushed plants with tap water + calmag, PH 6.5. Used 120L total for 4 plants in 2 days. 1st day: flushed after lights on, did not water until 2 hours before lights off and flushed again. Runoff PH went up a little, but not to the correct range. 2nd day: flushed after lights on and checked runoff EC + PH, of each plant. Fortunately, PH got corrected to 5.8, and I returned to automatic watering 4 times a day (with 10%-20% runoff). Thoughts: In the last grow, I thought I had a problem because of salts buildup in the media with constantly low PH in late flower. I didn't fully correct the problem till chop day. Same problem here in the same stage of flower without the salt buildup. After reading every forum I could find about the problem, I understood that my bloom nutes were the main problem because of their chemical composition. The coco ability to exchange ions lead to the low PH in the rootzone. It got worse quickly because I did not use any tap water with the feedings, so the PH could swing easily and drastically without resistance. After I looked online for the T.A. feeding chart, I saw they used TriPart Grow till week 7 of flower, the Nitrogen type they are using will up the PH. CocoForCannabis chart that I'm using, has not enough nitrogen to combat the bloom nutes PH down effect in flower. It gets even worse with RO water because there are no minerals that can resist PH down. Now I'm using 30% tap water with rest RO water, T.A. TriPart feeding chart with calmag and silica. Hopefully I have corrected the problem for the rest of the grow. It wasn't easy, because there were lots of variables that worsened the problem quickly. Now I'm checking runoff PH and EC daily. Update on next week :)