Future #1🎵

The development on this girl is amazing! The leaves appear slightly droopy, and judging by the color of the aztecs the soil isn't in perfect balance yet. I suspect the compost added in the layer under the top soil hasn't finished decomposing or the roots has hit a nitrogen hot-spot, causing slight stress to the roots, but the condition is not severe enough to warrant any corrective action at this stage. I will allow the plant to acclimate and compete for resources alongside the Aztecs. While it is still somewhat stout, the thick stem is a promising indicator of growth potential, and I have high expectations for this specimen. --- I synthesized dilute nitric acid (HNO₃) due to restrictions on purchasing. I avoid using phosphoric acid (H₃PO₄), given its tendency to precipitate various soil ions, preferring instead to derive phosphorus from potassium hydrogen phosphate (K₂HPO₄) and using HCL in small amounts 1-3ppm Cl, and if more pH- is needed I use HNO₃. 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 added all the condensed liquid to the main vessel, mixed it and titrated a known volume of potassium hydroxide 10mg/ml (KOH) drop by drop into 10ml of the acid, mixed with a pH indicator to verify the concentration of the resulting nitric acid. I then diluted the acid to approximately 2% HNO₃(1,91%, 0.303M), 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 (0.303 M) to the 1400 ml nutrient solution to lower pH from 6.8 to 6.5 while providing additional N 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 and sulphuric acid turns calcium into insoluble calcium sulphate, while HCL works, but Cl is just needed in trace amounts ~3ppm, so yeah HNO₃ is king, espec for veg, but also for flowering in limited amounts as the plant needs N in all stages of its life-cycle, less so in flowering phase, but then I don't worry muchb about pH reaching close to 7 so less acid is used. Every ml of N-acid increases NO3 by roughly 19ppm, so 1-5 ml is OK even in flowering phase and I rarely go beyond 3ml/l even in veg.