Feed and pH calculators for cannabis grows

Soil cannabis stage ranges: seedling 0.4–0.8 EC, veg 1.2–1.8 EC, early flower 1.6–2.2 EC, late flower 1.4–2.0 EC. Coco runs about 20% higher across all stages because coco's CEC binds nutrients more aggressively, so plants effectively see less than what's measured in the feed. Hydro runs similar to coco. Living soil ignores EC math entirely — biology controls availability, so EC measurements aren't meaningful. Start at the low end of each range and work up; underfeeding is recoverable, overfeeding stresses plants and can take 2 weeks to flush back to neutral.

Soil cannabis: pH 6.0–6.8, target around 6.3–6.5 for best availability of all macros and micros. Coco and hydro: pH 5.5–6.2, target 5.8 for the same balanced availability. Why different? Soil's CEC and microbial activity buffer pH, so a wider range works without lockout. Coco and hydro have no buffering — pH affects availability instantly and dramatically. Drift the pH 0.5 outside the range and certain nutrients lock out (calcium and magnesium drop first, iron and manganese follow). The Feed Health Tracker (in development) will alert you when input or runoff pH drifts outside the target range.

Salts are accumulating in the substrate. Plants take up water faster than they take up nutrients, so unused salts concentrate as the substrate dries between waterings. Runoff EC 0.3+ above feed EC means meaningful buildup. Runoff EC 0.6+ above feed means salt stress is approaching — plants will start showing tip burn within days. Solutions: water with plain pH'd water for 1–2 cycles to flush, then resume at lower feed EC. Alternatively, reduce feed concentration by 25% and increase water volume per watering to 20% runoff. The Feed Health Tracker handles this calculation automatically once it ships.

Both are accurate; the difference is which conversion factor they use to translate EC into PPM. 500 scale (Hanna, most US meters): PPM = EC × 500. 700 scale (Bluelab, most EU meters): PPM = EC × 700. Same actual nutrient concentration reads as different PPM numbers depending on scale. Confusion arises when comparing readings between people using different meters. The PPM/EC Converter handles the conversion in both directions. For new growers: get a meter that reads in EC primarily — EC has no scale ambiguity, it's the same number worldwide.

For quality: yes. For yield: no — flush actually slightly reduces final yield because the plant has fewer nutrients available in the last 1–2 weeks. The trade-off: smoother smoke, whiter ash, less harsh exhale, better terpene expression. Most growers can taste the difference between flushed and unflushed bud after a 4-week cure. Flush duration: 7–14 days for soil, 5–7 days for coco, 3–5 days for hydro. Pre-harvest flush isn't the same as a corrective flush mid-grow (used for salt buildup or lockout) — different goals, different durations, different success criteria. The Flush Tracker (in development) handles pre-harvest specifically.

Both work. Synthetic (FoxFarm Trio, GH Flora, Jack's, Advanced Nutrients): faster results, more predictable, easier to dial in by EC numbers, requires more attention to flushing. Organic / living soil: more forgiving of mistakes (biology buffers errors), produces arguably richer terpene profiles, requires less measurement once dialed in, can't really be measured by EC. For first grows: synthetic is easier because the math is direct — feed at this EC, get this result. For grows 3+: explore living soil if you want lower-maintenance once the soil web is established. Hybrid approaches (synthetic base + organic teas + cover crop) are common among experienced growers.