San Fernando Lemon Kush

OK development, not 100% perfect as the cotyledon is slightly bruised, yet nothing in particular going bad either. She reminds me of another strain from sweet seeds I cultivated few months ago - red hot cookies, very symmetric and vigorius growth! No further comments, she is doing allright I think :) -- I synthesized dilute nitric acid (HNO₃) due to restrictions, which I commonly use for pH adjustments. I avoided using phosphoric acid (H₃PO₄), given its tendency to precipitate various soil ions, preferring instead to derive phosphorus from potassium hydrogen phosphate (K₂HPO₄). With access to hydrochloric acid (HCl) and calcium nitrate (Ca(NO₃)₂), I utilized a closed-loop gas recirculation system with copper as a catalyst to generate HNO₃. The system included a triple-barrier setup with diluted hydrogen peroxide (H₂O₂) to absorb nitrogen dioxide (NO₂) and nitrogen tetroxide (N₂O₄) gases, thus converting Ca(NO₃)₂ to HNO₃ without venting any gases. This controlled approach minimized exposure to toxic NOx fumes, which are both harmful and wasteful if released. Once gas absorption was complete, I titrated a known volume of potassium hydroxide (KOH) to verify the concentration of the resulting nitric acid. I then diluted the acid to approximately 2% HNO₃, as this concentration reduces the risk of skin irritation and staining upon accidental contact, compared to the hazards of 69% or fuming nitric acid. Even if 3% conc is still legal w/o papers in most of EU I felt 1-2% was more my to my taste and in line with the 1% HCL and 0,75% phosphoric acid used as pH-. Added 2 ml of ~2% HNO₃ (0.3 M) to the 1400 ml nutrient solution to lower pH from 6.8 to 6.5 while providing additional nitrogen for improved seedling vigor. HNO₃ was selected over H₂SO₄, H₃PO₄, or HCl due to its dual function: it supplies bioavailable nitrogen and effectively solubilizes calcium into Ca(NO₃)₂, enhancing root uptake, whereas H₃PO₄ would risk forming insoluble calcium phosphate. --- To regenerate pure copper from the catalyst, I utilized the aluminum from two empty Red Bull cans as a cost-effective alternative to expensive aluminum foil. I first added the aluminum to the copper chloride (CuCl) slurry, facilitating its conversion to aluminum chloride (AlCl₃). After the conversion, I rinsed the mixture with water to dissolve the aluminum chloride, allowing the copper to be washed out. The copper was then filtered from the solution. Next, I heated the resulting liquid, allowing the gases released during the process to bubble through a vessel filled with ice water. This setup effectively condensed the vapor, facilitating the recovery of hydrochloric acid (HCl). Finally, I distilled the collected HCl to reclaim the original reagents. Throughout this procedure, the only resources lost were inexpensive Ca(NO₃)₂ + thermal energy and time, indicating a high efficiency in material recovery & no harm to the environment. Same logic as with recovering soil from the previous grow to keep a low profile and reduce the eco footprint. Same soil used since 2016, increasing in volume for every year as I keep recycling/composting the leftover leaves, stems, and root-systems over and over from previous grows. ---