Nutrient Dosing & Dilution Calculator
Correct your target EC for your source water’s baseline, or figure out how much water to add to bring an over-strength reservoir back down.
Aim for a total meter reading of 1.7 mS/cm
Your meter can’t tell baseline minerals apart from added nutrient. If your chart’s target assumes near-zero source water (common for extension/lab figures), mixing only to that number undershoots the intended nutrient strength by your baseline amount — this adds your baseline on top so the actual nutrient concentration matches the chart. If your own chart already specifies a fixed total reading regardless of source water, don’t add baseline again on top of it.
Check crop-specific target EC ranges on the EC/pH reference chart, and convert between EC and PPM on the EC/PPM converter.
Frequently asked questions
- Why does my source water's baseline EC matter?
- Tap water isn't EC-zero — dissolved minerals (mainly calcium, magnesium, and bicarbonates) already register on your meter before you add any nutrient (RO permeate is usually very close to zero, but check it rather than assume). If a feeding chart's target assumes near-zero source water and yours reads 0.3 mS/cm on its own, mixing only to the chart's 1.4 mS/cm total actually gives you just 1.1 mS/cm of real nutrient — an under-dose relative to what the chart intended, not an over-dose.
- How do I measure my source water's baseline EC?
- Fill your reservoir with plain source water (no nutrient added yet) and take an EC reading before mixing anything in. Do this at the start of each fresh reservoir fill rather than assuming a fixed number — water chemistry can vary seasonally and between fills, especially with municipal tap water. Take both readings at a similar temperature, or use a meter with automatic temperature compensation — EC changes roughly 2% per °C, which can rival the baseline correction itself.
- Does the dilution calculator assume my dilution water is EC-zero?
- No — it asks for your dilution water's own EC and accounts for it in the calculation, rather than assuming pure water. If you're diluting with true 0-EC RO water, just enter 0. Note that dilution corrects EC but not nutrient ratios or pH — recheck pH after diluting, especially with alkaline tap water.
- What does over-fertilizing actually do to my plants?
- Excess EC causes osmotic stress: roots struggle to take up water against the concentrated solution, showing as wilting even in wet media, leaf-margin necrosis, and stunted growth. If a reservoir tests well above target, dilute promptly rather than waiting — and expect reservoir EC to drift upward over time between refills as plants take up water faster than dissolved salts ("EC creep"), so recheck periodically rather than only at mix time.