Calculator Inputs
Example Data Table
| Volume (L) | Current (ppm) | Target (ppm) | Increase (ppm) | Strength (ppm per mL per L) | Estimated Dose (mL) |
|---|---|---|---|---|---|
| 10 | 250 | 850 | 600 | 10 | 600 |
| 20 | 300 | 900 | 600 | 12 | 1000 |
| 5 | 150 | 450 | 300 | 8 | 187.5 |
Example doses assume no loss adjustment and no rounding.
Formula Used
- Delta = Target - Current
- mg_needed ≈ Delta(ppm) × Volume(L) (1 ppm ≈ 1 mg/L)
- Strength method: mL = (Delta / Strength) × Volume(L)
- Density method: mL = mg_needed / (mg per mL)
- Loss adjustment: Dose × (1 + Loss%/100)
This is a practical mixing estimate. Add in steps and re-test to avoid overshooting.
How to Use This Calculator
- Measure your current solution using a clean meter.
- Select ppm or EC to match your meter display.
- Enter your water volume and choose the unit.
- Set a target that matches your growth stage.
- Pick a dose method that matches your product label.
- Calculate, then add nutrients gradually and mix well.
- Re-test after a few minutes and fine-tune if needed.
Practical Notes
Why TDS increases matter in gardening
In container growing and hydro-style feeding, total dissolved solids provide a quick snapshot of overall nutrient strength. Raising TDS helps match the plant’s demand as it moves from early growth to heavy uptake. This calculator estimates how much concentrate to add so the jump in strength is controlled rather than guesswork. Treat readings as trends: water source, additives, and plant uptake can shift the numbers during the day.
Interpreting ppm and EC scales
Meters can display either EC (mS/cm) or ppm derived from EC using a conversion factor. Common scales include 0.5, 0.64, and 0.7. Two growers may read the same solution differently if their meters use different scales, even though the solution itself is identical. The factor selector helps you translate between displays so your target remains consistent. When sharing recipes, include the scale and the water temperature when possible.
Choosing a dosing method that matches your product
Some nutrient labels describe effect as “mL per liter,” while others provide grams, percentages, or density. This tool supports two practical inputs: a strength rating (ppm increase per mL per liter) or a density rating (mg per mL). If you have repeated observations, you can back-calculate a reliable strength rating for your brand and keep it for future mixes. For new products, start with a conservative dose and verify with re-testing.
Managing losses, mixing, and measurement drift
Real mixing includes small losses: residue in measuring cups, incomplete dissolution, and minor overshoot corrections. The loss adjustment field adds a buffer to account for that. Mix thoroughly, wait a few minutes, and measure again with a rinsed probe. If your solution contains organics or additives that coat sensors, clean the probe regularly. Consistent technique improves repeatability more than chasing an exact number every time.
Safer step-up strategy for sensitive plants
Instead of adding the full calculated amount at once, split the dose into two or three steps. Add half, mix, re-test, then top up gradually. This reduces the chance of overshooting and makes it easier to adapt to cultivar sensitivity and environmental changes. Keep notes on volume, target, and final reading so you can refine your strength setting over time. Consistency is the real advantage of a calculator-driven workflow.
FAQs
1) Is TDS the same as nutrients?
No. TDS is a combined measure of dissolved ions and salts, not a nutrient breakdown. It helps track strength changes, but it cannot confirm specific elements or pH-related availability.
2) Which factor should I pick: 0.5, 0.64, or 0.7?
Pick the factor that matches your meter’s manual or settings. If unsure, use EC mode and share targets in EC to avoid scale confusion.
3) Why does my reading change after mixing?
Temperature stabilization, incomplete dissolution, and sensor settling can shift readings. Mix well, wait a few minutes, then measure again with a clean probe.
4) Can I use this for soil feeding?
Yes, for mixing feed water. Soil buffers nutrients differently than hydro systems, so increase targets gradually and monitor plant response instead of relying only on the number.
5) What does “ppm per mL per L” mean?
It is an observed strength rating: how many ppm your solution rises when you add 1 mL of concentrate to 1 liter. You can estimate it by testing a known small dose.
6) How do I avoid overshooting my target?
Use the rounding control, add in steps, and re-test between additions. If you overshoot, dilute with plain water, mix, and re-check before adding more.