\n| Cannabis<\/td>\n | 1.6\u20132.0<\/td>\n | 2.0\u20132.8<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n Holding EC within \u00b10.1 mS\/cm of target<\/strong> is a routine expectation for a modern automated dosing system.<\/p>\n<\/span>Cell Type: Two-Electrode vs. Toroidal<\/span><\/h2>\nTwo cell technologies dominate hydroponic and greenhouse EC control.<\/p>\n Two-electrode cells<\/strong> use graphite, platinum, or stainless surfaces to inject an AC current and measure conductance. They are inexpensive, accurate at low-to-medium EC (up to ~20 mS\/cm), and easy to clean. Their weakness is electrode polarization<\/strong> at high salt concentrations and fouling<\/strong> from biofilm or nutrient scaling.<\/p>\nToroidal (inductive) cells<\/strong> measure the current induced in a fluid loop threaded through two toroidal coils. They have no electrodes in contact with the sample, so polarization and biofouling are eliminated. Range extends to hundreds of mS\/cm, making them suitable for stock-solution feed lines<\/strong> where undiluted A- and B-tanks reach 60\u2013100 mS\/cm.<\/p>\nIn practice, most greenhouse recirculation loops run on two-electrode stainless cells<\/strong>, while toroidal cells<\/strong> are reserved for stock-solution mixing and high-EC media. Shanghai ChiMay offers both formats within the same in-line conductivity family.<\/p>\n<\/span>Temperature Compensation Is Not Optional<\/span><\/h2>\nConductivity of aqueous salt solutions rises by roughly 2% per \u00b0C<\/strong>. In a greenhouse where nutrient solution temperature swings from 15 \u00b0C at dawn to 26 \u00b0C by afternoon, uncompensated EC readings drift by more than 20%. Automatic Temperature Compensation (ATC) using a matched Pt1000 or NTC element referenced to 25 \u00b0C standard<\/strong> is the industry norm.<\/p>\nField engineers should confirm three things about ATC:<\/p>\n \n- The temperature sensor is integral to the conductivity cell<\/strong>, not remote \u2014 remote sensors miss transient thermal gradients.<\/li>\n
- The transmitter allows selectable compensation curves<\/strong> (linear, non-linear NaCl, non-linear pure water) to match the medium.<\/li>\n
- Reference temperature is user-configurable; 25 \u00b0C<\/strong> is standard for nutrient solutions.<\/li>\n<\/ol>\n
<\/span>Injection Point Geometry<\/span><\/h2>\nPoor injection geometry causes 80% of EC-based dosing instability. The typical failure mode is oscillation: the EC probe reads a slug of concentrated feed, the controller reduces dosing sharply, the next section of pipe reads low, dosing surges again, and the loop oscillates around setpoint rather than settling. Engineering guidance:<\/p>\n \n- Locate the EC probe at least 10 pipe diameters downstream<\/strong> of the last injection point to allow mixing.<\/li>\n
- Ensure turbulent flow<\/strong> at the probe location; Reynolds numbers above 4,000 mix well, below 2,000 do not.<\/li>\n
- Where straight-run is unavailable, use a static mixer<\/strong> upstream of the probe. Static mixers are inexpensive and shorten the required straight-run by 60\u201370%.<\/li>\n
- Position the probe on a horizontal run with the cell downward-pointing<\/strong>, so air bubbles do not collect on the sensor face.<\/li>\n<\/ul>\n
<\/span>Control Loop Tuning<\/span><\/h2>\nEC-based dosing is a PID control problem. Field-proven defaults for greenhouse fertigation:<\/p>\n \n- P-band<\/strong>: 0.2 mS\/cm around setpoint.<\/li>\n
- Integral time<\/strong>: 30\u201360 seconds.<\/li>\n
- Derivative<\/strong>: usually zero \u2014 the process is slow enough that derivative action introduces noise.<\/li>\n
- Output limits<\/strong>: dosing pumps limited to 80% of maximum stroke rate to preserve control margin.<\/li>\n<\/ul>\n
Anti-windup on the integral term is essential when dosing pumps saturate; without it, EC overshoots on recovery from a stock-tank fill.<\/p>\n <\/span>Calibration and Verification Discipline<\/span><\/h2>\nEC cells drift. Even a well-maintained two-electrode cell drifts about 1\u20132% per month<\/strong> under fertigation service. The correct calibration schedule is two-point calibration every 30 days<\/strong> using 1.413 mS\/cm<\/strong> and 12.88 mS\/cm<\/strong> standards traceable to national metrology institutes. A single-point calibration in the crop’s normal EC band is acceptable for weekly verification but not a substitute for two-point.<\/p>\nRecommended documentation per cell:<\/p>\n \n- Cell serial number, install date, and expected replacement date.<\/li>\n
- Calibration log with before-and-after readings and technician initials.<\/li>\n
- Cleaning log noting method and frequency (typically isopropanol wipe monthly<\/strong>; dilute HCl soak quarterly<\/strong> for scaled cells).<\/li>\n<\/ul>\n
<\/span>Troubleshooting Field Symptoms<\/span><\/h2>\n\n\n\n| Symptom<\/th>\n | Likely Cause<\/th>\n | Corrective Action<\/th>\n<\/tr>\n<\/thead>\n | \n\n| EC reading drifts high<\/td>\n | Salt encrustation on electrodes<\/td>\n | HCl soak, 5\u201310 minutes<\/td>\n<\/tr>\n | \n| EC reading drifts low<\/td>\n | Air bubble on cell face<\/td>\n | Reorient probe downward, add air release<\/td>\n<\/tr>\n | \n| EC oscillates around setpoint<\/td>\n | Insufficient mixing pre-probe<\/td>\n | Move probe further downstream or add static mixer<\/td>\n<\/tr>\n | \n| EC unresponsive to dosing<\/td>\n | Cable damage or ground loop<\/td>\n | Insulate cable, verify shield termination<\/td>\n<\/tr>\n | \n| Sudden EC spike<\/td>\n | Stock-solution tank refill event<\/td>\n | Add ramp filter to controller input<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/span>What Shanghai ChiMay Provides for EC Control<\/span><\/h2>\nShanghai ChiMay’s in-line conductivity meter<\/strong> and in-line conductivity electrode<\/strong> are offered in two-electrode stainless (0\u201320 and 0\u2013100 mS\/cm) and toroidal (0\u20132000 mS\/cm) variants. Both share the same PG13.5 threaded body geometry, so growers can swap technology as the loop demands without changing plumbing. Integral Pt1000 temperature sensing and selectable compensation curves are standard, and the 2-in-1 mini transmitter offers 4\u201320 mA and Modbus RTU with a configurable PID output loop suitable for direct dosing-pump control.<\/p>\nFor growers scaling from a single fertigation loop to multi-zone facilities, the shared transmitter family means one training curriculum, one calibration procedure, and one spare-parts SKU across the whole operation.<\/p>\n <\/span>Closing Note<\/span><\/h2>\nEC-based dosing is deceptively simple. The concept \u2014 hold conductivity at setpoint \u2014 hides real engineering in cell selection, temperature compensation, injection geometry, and control tuning. Growers who invest in the right cell, treat calibration as a scheduled maintenance event, and get the injection geometry correct will hold nutrient concentration within tight tolerance for years. That precision is the difference between a hydroponic operation that beats its yield model and one that underperforms it by 10% every season.<\/p>\n","protected":false},"excerpt":{"rendered":" title: “EC-Based Nutrient Dosing Control for Hydroponic and Greenhouse Systems: Field Practices from Shanghai ChiMay” perspective: Technical theme: Agricultural Irrigation & Water Reuse date: 2026-07-05 EC-Based Nutrient Dosing Control for Hydroponic and Greenhouse Systems: Field Practices from Shanghai ChiMay Key Takeaways Electrical conductivity (EC) is the practical proxy for total dissolved fertilizer salts in hydroponic…<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"_kad_post_transparent":"","_kad_post_title":"","_kad_post_layout":"","_kad_post_sidebar_id":"","_kad_post_content_style":"","_kad_post_vertical_padding":"","_kad_post_feature":"","_kad_post_feature_position":"","_kad_post_header":false,"_kad_post_footer":false},"categories":[1],"tags":[158,134429,134481],"translation":{"provider":"WPGlobus","version":"3.0.2","language":"es","enabled_languages":["en","es","fr","ru","ar"],"languages":{"en":{"title":true,"content":true,"excerpt":false},"es":{"title":false,"content":false,"excerpt":false},"fr":{"title":false,"content":false,"excerpt":false},"ru":{"title":false,"content":false,"excerpt":false},"ar":{"title":false,"content":false,"excerpt":false}}},"_links":{"self":[{"href":"https:\/\/www.chimaytech.net\/es\/wp-json\/wp\/v2\/posts\/31139"}],"collection":[{"href":"https:\/\/www.chimaytech.net\/es\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.chimaytech.net\/es\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.chimaytech.net\/es\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.chimaytech.net\/es\/wp-json\/wp\/v2\/comments?post=31139"}],"version-history":[{"count":0,"href":"https:\/\/www.chimaytech.net\/es\/wp-json\/wp\/v2\/posts\/31139\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.chimaytech.net\/es\/wp-json\/wp\/v2\/media?parent=31139"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.chimaytech.net\/es\/wp-json\/wp\/v2\/categories?post=31139"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.chimaytech.net\/es\/wp-json\/wp\/v2\/tags?post=31139"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}} | |