Day 98. Week seven of 12/12 light flowering stage.

Conditions: 1.2mS/cm. Ph 5.8, CO2 modified to min level of 500ppm, Light 12/12 @ 800 PPFD, down from 1K+. Day 80F(max), Night 65F (min.) RH Day 55% Night 50%. Discontinued use of close- loop AC & dehumidifier grow tent environment control. Think there may have been some issues developing with recycling of grow tent air with closed loop AC/dehumidifier usage and lack of fresh air room exchange which was zero for a week.

Lots of new things this week. Growth and bud development continues. But… Started noticing a decrease in “Fragrance” and lack of resin on the upper growth. Lower growth and “shaded/lower bud still were nice and “Sticky” with resin and had a wonderful bouquet. Pretty sure the top portions of the girls were screaming “Too Much Light”. Had been running 1K+ PPFD. Still running the lights @ 100%. but raised the lights till the PPFD was down to 800. Not 100% sure the light intensity was the issue, but a reasonable guess. Not sure if the stickiness and bouquet will return to, the top buds, but fingers crossed. Watching things closely.

Did install a set of dual AUX. UV-B light bars, but with the above issues decided to put their use on hold, at least for now. Don’t real want to introduce a new variable into an otherwise very good first-time hydro/CO2 grow.

While there is a considerable number of generalities out the on the web. One specific well detailed recent scientific paper ( https://doi.org/10.3389/fpls.2021.725078 ) pretty much demonstrates that exposure to UV-B results in general decreased plant health. If the Aux UV-B bars are ever used, it will be with caution.

Have not mentioned, but think is important to pass on, with this hydro-CO2 grow. 50% +/- of the water reservoir, 25 gallons of 50, is drained and refilled every two weeks (Sundays) & Ph adjusted. Since using well water with known iron bacteria present, a submerged 13W UV-C light (Amazon $29) is run on Sundays, during the “Twelve-hour daylight, watering cycle (15 seconds on / 20 minutes off)”. Effectively reducing both good & bad bacteria/algae counts in the reservoir and the return water.

On Mondays, EC is adjusted based on growth stage (Veg vs Flower), & a small amount of micro-nutrients is added because of general understanding that UV-C tendencies to breakdown of Fe-chelate and other necessary nutrients/enzymes, along with a 30ml shot of “HydroGuard” bacteria to repopulate the water reservoir with “good bacteria” The above, whether the best or most efficient practice is justified, it does seem to be working very well in producing healthy girls. Lastly, a continuous air stone in the water reservoir provides agitation and help to keep the water oxygenated.

This Sunday, with just 2-3 weeks to harvest, it’s time to flush the girls clean. Water exchange will be a full drain and 100% fresh water, Ph adjusted to 5.8, UV-C treatment, add hydrogen peroxide at the rate of 3ml/gallon. After a few days to let the HP dissipate, add Hydroguard per instructions.