if it were me i wold try kicking up the ppm to 1000-1100 and use 10ml of calmag per gallon as that is the "heavy dose"
the plants are growing at a high rate at this stage and need lots of nutes to make those sweet buds. :)
ppm is only at 850? that seems low for 3-4 weeks in flowering imo.
does your led light have a few uvb led's in the middle? might be that if so since it is localized under the led. i highly doubt it, but just a thought.
thanks for the tip on the cooling line. i was in a hurry so i didn't get too fancy, or put a lot of thought into it. i thought about doing it like yours and keep the coolant seperate from the actual res water like a heat exchanger. ill probably modify it like that on the next go round.
This is my first attempt at hydro with a home built dutch bucket/ top feed system. My current nutes are Fox Farms Grow Big Hydro, Big Bloom, General Hydro's Silica Blast, Advanced Organic B1, and Organic Cal Mag Plus. My medium is the recycled glass Growstone. I also had a little left over...