{"@context":"https://schema.org","@type":"TechArticle","id":"MTH-STK-001","slug":"stock-solutions","canonical_url":"https://flavorotor.com/research/stock-solutions","machine_readable_url":"https://flavorotor.com/research/data/chapters/stock-solutions.json","markdown_url":"https://flavorotor.com/research/markdown/stock-solutions","title":"Nutrient stock solutions","description":"How stock composition, compatibility, dose volume and reservoir volume define nutrient additions without inventing ion-specific EC values.","chapter":"Nutrient dosing","version":"1.1","updated":"2026-07-26","table_of_contents":[{"id":"principle","label":"Principle"},{"id":"compatibility","label":"Stock compatibility"},{"id":"recipe-solving","label":"Recipe solving"},{"id":"ion-coupling","label":"Ion coupling"}],"html":"<section aria-label=\"Article summary\" class=\"fr-article-summary\"><div><span>In brief</span><p>How stock composition, compatibility, dose volume and reservoir volume define nutrient additions without inventing ion-specific EC values.</p></div></section><h2 id=\"principle\">Principle</h2>\n<p>Each stock solution is defined by the concentration of every relevant chemical species, not by a marketing label. The controller calculates the amount added to the reservoir from calibrated dose volume and stock composition.</p>\n<div class=\"equation\"><div class=\"equation-label\">STK-1</div><div class=\"equation-text\">Δc<sub>i</sub> = S<sub>ij</sub> · v<sub>j</sub> / V<sub>R</sub></div><div class=\"equation-desc\">Increase in reservoir concentration of ion i from stock j, where Sij is stock concentration, vj is dose volume and VR is reservoir volume.</div></div>\n<div class=\"equation\"><div class=\"equation-label\">STK-2</div><div class=\"equation-text\">c<sub>i,k+1</sub> = c<sub>i,k</sub> + ΣΔc<sub>i</sub> − u<sub>i,k</sub> − l<sub>i,k</sub></div><div class=\"equation-desc\">Ion inventory update including additions, plant uptake ui and other losses li.</div></div>\n<h2 id=\"compatibility\">Stock compatibility</h2>\n<p>Concentrated calcium stocks are separated from concentrated phosphate or sulphate stocks unless compatibility has been demonstrated, because precipitation can remove nutrients and obstruct tubing. Stock identity, concentration, solvent, preparation date, lot and storage conditions are recorded.</p>\n<h2 id=\"recipe-solving\">Recipe solving</h2>\n<p>When several stocks contribute to several ions, the system solves a constrained non-negative dosing problem rather than assigning one pump to one sensory attribute.</p>\n<div class=\"equation\"><div class=\"equation-label\">STK-3</div><div class=\"equation-text\">min ||S·v − Δc<sub>target</sub>||² subject to v ≥ 0 and v ≤ v<sub>max</sub></div><div class=\"equation-desc\">Constrained stock-volume selection for a target ion-change vector.</div></div>\n<aside class=\"fr-engineering-note\"><strong>Control rule</strong><p>EC is used as a bulk consistency and safety check. It cannot verify the individual ion vector S·v.</p></aside><h2 id=\"ion-coupling\">Ion coupling</h2><p>Stock design accounts for the fact that fertilizer salts introduce coupled ions and that precise individual-ion control requires more information than bulk EC. <button aria-label=\"Open source record R34\" class=\"research-source-trigger\" data-research-source=\"R34\" type=\"button\">[R34]</button> <button aria-label=\"Open source record R35\" class=\"research-source-trigger\" data-research-source=\"R35\" type=\"button\">[R35]</button> <button aria-label=\"Open source record R36\" class=\"research-source-trigger\" data-research-source=\"R36\" type=\"button\">[R36]</button></p>","text":"In brief How stock composition, compatibility, dose volume and reservoir volume define nutrient additions without inventing ion-specific EC values. Principle Each stock solution is defined by the concentration of every relevant chemical species, not by a marketing label. The controller calculates the amount added to the reservoir from calibrated dose volume and stock composition. STK-1 Δc i = S ij · v j / V R Increase in reservoir concentration of ion i from stock j, where Sij is stock concentration, vj is dose volume and VR is reservoir volume. STK-2 c i,k+1 = c i,k + ΣΔc i − u i,k − l i,k Ion inventory update including additions, plant uptake ui and other losses li. Stock compatibility Concentrated calcium stocks are separated from concentrated phosphate or sulphate stocks unless compatibility has been demonstrated, because precipitation can remove nutrients and obstruct tubing. Stock identity, concentration, solvent, preparation date, lot and storage conditions are recorded. Recipe solving When several stocks contribute to several ions, the system solves a constrained non-negative dosing problem rather than assigning one pump to one sensory attribute. STK-3 min ||S·v − Δc target ||² subject to v ≥ 0 and v ≤ v max Constrained stock-volume selection for a target ion-change vector. Control rule EC is used as a bulk consistency and safety check. It cannot verify the individual ion vector S·v. Ion coupling Stock design accounts for the fact that fertilizer salts introduce coupled ions and that precise individual-ion control requires more information than bulk EC. [R34] [R35] [R36]","source_ids":["R34","R35","R36"],"visuals":[],"sources":[{"id":"R34","authors":"Cho, Woo-Jae; Gang, Min-Seok; Kim, Dong-Wook; Kim, JooShin; Jung, Dae-Hyun; Kim, Hak-Jin","year":2023,"title":"Decision-tree-based ion-specific dosing algorithm for enhancing closed hydroponic efficiency and reducing carbon emissions","publication":"Frontiers in Plant Science, 14, 1301490","doi":"10.3389/fpls.2023.1301490","source_type":"peer-reviewed engineering research","relevance":"Demonstrates ion-specific monitoring and multi-stock dosing while accounting for coupled ions in fertilizer salts.","verification":"Publisher metadata and full text checked 2026-07-26","url":"https://doi.org/10.3389/fpls.2023.1301490","verified_on":"2026-07-26","verification_status":"DOI METADATA CHECKED","verified_against":"Publisher, DOI landing page, PubMed or official repository where available"},{"id":"R35","authors":"Bamsey, Matthew; Graham, Thomas; Thompson, Cody; Berinstain, Alain; Scott, Alan; Dixon, Michael","year":2012,"title":"Ion-Specific Nutrient Management in Closed Systems: The Necessity for Ion-Selective Sensors in Terrestrial and Space-Based Agriculture and Water Management Systems","publication":"Sensors, 12, 13349–13392","doi":"10.3390/s121013349","source_type":"peer-reviewed review","relevance":"Explains why closed nutrient systems require ion-specific information when precise ionic balance is the objective.","verification":"Publisher metadata checked 2026-07-26","url":"https://doi.org/10.3390/s121013349","verified_on":"2026-07-26","verification_status":"DOI METADATA CHECKED","verified_against":"Publisher, DOI landing page, PubMed or official repository where available"},{"id":"R36","authors":"Miller, Alexander; Adhikari, Ranjeeta; Nemali, Krishna","year":2020,"title":"Recycling Nutrient Solution Can Reduce Growth Due to Nutrient Deficiencies in Hydroponic Production","publication":"Frontiers in Plant Science, 11, 607643","doi":"10.3389/fpls.2020.607643","source_type":"peer-reviewed research","relevance":"Shows that maintaining target EC in recycled hydroponics can mask individual nutrient deficiencies and unwanted-ion accumulation.","verification":"Publisher full text checked 2026-07-26","url":"https://doi.org/10.3389/fpls.2020.607643","verified_on":"2026-07-26","verification_status":"DOI METADATA CHECKED","verified_against":"Publisher, DOI landing page, PubMed or official repository where available"}]}