What is the injection rate?

The injection rate is the volume of concentrated stock solution the pump delivers per hour (L/hr). It equals the irrigation flow rate divided by the injector ratio. For example, at 1000 L/hr flow and a 1:200 ratio, the injection rate is 5 L/hr.

How is delivered ppm calculated?

Delivered ppm (mg/L) = stock concentration (g/L) × 1000 ÷ injector ratio. If your stock is 200 g/L and the ratio is 1:200, delivered ppm = 200 × 1000 / 200 = 1000 ppm. This assumes the fertilizer nutrient fraction equals 100%; adjust the nutrient percentage field for real products.

What injector ratio should I use?

Venturi injectors commonly operate at 1:100. Dosatron units cover 1:50 to 1:500. Lower ratios (e.g. 1:50) deliver more stock per liter of water, which is useful when the maximum pump rate is limited. Higher ratios (1:200+) use less stock and reduce over-dosing risk if the injector sticks open.

What is a stock solution?

A stock solution is a concentrated fertilizer solution prepared in a tank. The injector dilutes it into the irrigation water at a fixed ratio, producing a much weaker working solution that contacts the plant roots. Common stock concentrations range from 50 to 500 g/L depending on fertilizer solubility.

Why does ppm differ from the label claim?

Fertilizer labels state the percentage of each nutrient (e.g. 20% N). The delivered ppm of that specific nutrient is the total fertilizer ppm multiplied by the nutrient percentage. Use the nutrient percentage field to convert total fertilizer ppm to elemental nutrient ppm.

How do I convert EC to ppm?

A common approximation is ppm ≈ EC (mS/cm) × 640 (Hanna factor) or × 700 (Truncheon factor). The exact conversion varies by fertilizer salt composition. This calculator works in ppm; divide your EC target by your preferred factor to get the ppm input.

Injection Pump Settings Calculator

Name: Injection Pump Settings Calculator
Availability: InStock
Author: Nham Vu

Enter your target nutrient ppm, irrigation flow rate, and injector ratio to get the precise injection pump rate and stock solution concentration needed for fertigation.

System Parameters

Irrigation Flow Rate (L/hr)

Total flow of the irrigation system

Injector Ratio (1 : X)

1 part stock per X parts irrigation water

Stock Solution Concentration (g/L)

Grams of fertilizer dissolved per liter of stock

Nutrient Content in Fertilizer (%)

E.g. 20 for a 20% N fertilizer; use 100 for pure nutrient ppm

Target Delivered Concentration (ppm)

Desired nutrient ppm in irrigation water (leave 0 to skip target check)

Common Injector Ratios

Venturi (standard)1 : 100

Dosatron D141 : 50 – 1 : 200

Dosatron D251 : 50 – 1 : 500

Bypass injector1 : 200 – 1 : 1000

Enter your system parameters and click Calculate Pump Settings.

Summary

Enter your target nutrient ppm, irrigation flow rate, and injector ratio to get the precise injection pump rate and stock solution concentration needed for fertigation.

How it works

Enter the irrigation system flow rate in liters per hour (L/hr).
Set the target nutrient concentration in the irrigation water (ppm = mg/L).
Enter the stock solution concentration — how many grams of fertilizer per liter of stock (g/L).
Set your injector ratio (e.g. 1:200 means 1 part stock per 200 parts water).
The calculator derives the injection rate (L/hr), actual delivered ppm, and dilution factor.
Adjust inputs until the delivered ppm matches your crop requirement.

Use cases

Set injector pump output for greenhouse hydroponic systems.
Verify fertigation settings before starting an irrigation event.
Calculate stock solution strength needed for a target EC or ppm.
Configure Dosatron or Venturi injectors for field drip systems.
Convert between injector ratio and injection rate for pump programming.
Scale fertigation programs from small trial plots to full production.
Train farm staff on the relationship between ppm, flow, and injector output.
Cross-check nutrient delivery when troubleshooting plant deficiencies.

Frequently Asked Questions

Last updated: 2026-06-09 · Reviewed by Nham Vu