Both plants are thriving by the end of week 11. The Hydro plant is much darker—a rich, deep green. It looks clearly healthier, larger, and denser than the Coco plant (which is on BioFeeding)—about two to three times the size. I’m going to give the Coco plant a single dose of Hesi Hydro Bloom. The hydroponic plant drops the pH to 5.5 every day. That’s the lower limit, and during the flowering stage, it’s better to keep it above 6. I drain 4–5 liters of the solution and top it up with reverse osmosis water containing CalMag and a pH of 7; I definitely add a liter every day.
I’ve only done a full solution change once during the flowering stage. A couple of days later, the new solution’s pH started dropping to the 5.1–5.5 range again. Without daily adjustments, nutrient lockout would certainly occur. DWC is very demanding; you can't leave it for a week without an automated pH system. Both plants have started budding; the hydro plant is developing dense bud sites all the way from the base, unlike the Coco plant in the 60x60x180 tent (which takes up a quarter of the space).
I’d like advice from anyone who has dealt with pH drops occurring 4–5 weeks after switching to a 12/12 light cycle: how can I stabilize the pH for the long term? Should I get a pH-up product?