Fertigation Stock Tank & Stock & Diluted Strength
Doses drip lines
Enter fertiliser amount, tank volume and injector ratio to get the stock solution concentrationand the diluted concentration that actually reaches the crop in the drip line.
Mix your stock tank
Next: dissolve 10 kg in 100 L; the injector at 1:100 delivers 1 g/L at the plants.
Keep the stock concentration below the fertilizer's solubility limit (and below ~200 g/L for most blends) so nothing precipitates and clogs the injector or emitters.
Fertigation stock tank — key facts
- Stock conc.
- fertiliser ÷ tank volume
- Diluted conc.
- stock ÷ injector ratio
- Injector ratio
- e.g. 1:100 stock to water
- Common range
- ≈ 1:50 to 1:200
- Stay below
- fertiliser solubility limit
- Separate tanks
- A/B for incompatible salts
- Verify
- EC meter on diluted line
- Privacy
- Runs in your browser; nothing uploaded
A small concentrated tank feeds a whole field
Fertigation rarely doses fertiliser straight into the full water supply. Instead a concentrated stock solution sits in a tank and an injector — a venturi or dosing pump — draws it into the irrigation line at a set ratio such as 1:100. That lets a modest tank fertilise a large area, and the injector ratio becomes the dial you turn to control exactly how strong the water reaching the crop is.
Two numbers matter: the stock concentration in the tank (fertiliser divided by tank volume) and the diluted concentration the crop receives (stock divided by the injector ratio). This tool returns both from your fertiliser amount, tank volume and ratio, so you can keep the stock within solubility limits while hitting the target feed strength. Pair it with the Fertigation, Acid Injection and Hydroponic Nutrient calculators for the full recipe.
Mix the stock right
Set tank concentration within solubility.
Hit the feed target
Know the strength reaching the crop.
Dial with the injector
Change ratio without remixing the tank.
Avoid clogging
Keep concentrate below solubility limits.
Frequently Asked Questions
What is a fertigation stock tank?+
A stock tank holds a concentrated fertiliser solution that is injected into the irrigation line at a fixed ratio rather than dosed straight into the whole water supply. Because only a small amount is injected per unit of irrigation water, a manageable tank can fertilise a large area, and the injector controls exactly how strong the water reaching the crop is.
How is stock concentration calculated?+
Stock concentration = fertiliser amount ÷ tank volume. For example 5 kg of fertiliser dissolved in a 100-litre tank gives 50 g/L of stock solution. That is the strength of the concentrate sitting in the tank, before it is diluted by injection into the irrigation water.
What is the injector ratio?+
The injector ratio is how much irrigation water each unit of stock solution is mixed into — written like 1:100, meaning one part stock to one hundred parts water. Venturi injectors, dosing pumps and proportional injectors all set this ratio; it determines how strong the diluted solution that actually reaches the crop will be.
How is the diluted concentration found?+
Diluted concentration = stock concentration ÷ injector ratio. So 50 g/L of stock at a 1:100 injector ratio reaches the crop at 0.5 g/L. The calculator works out both the stock concentration in the tank and this diluted concentration in the drip line from your fertiliser, tank volume and ratio.
Why dose from a concentrated stock instead of the whole tank?+
Injecting a concentrate lets a small tank treat a large irrigation flow, keeps the fertiliser easy to mix and store, and lets you change the injector ratio to fine-tune crop feeding without remixing. It also means you can run the same stock at different strengths simply by adjusting the injector.
What injector ratio should I use?+
It depends on your injector and target feed strength; common venturi and dosing-pump ratios run from about 1:50 to 1:200. Set the ratio so the diluted concentration matches the crop's recommended feed (often a fraction of a gram of nutrient per litre), then keep the stock concentration within the fertiliser's solubility limit.
Can I keep different fertilisers in one stock tank?+
Be careful — some fertilisers react and precipitate when combined (for example calcium with phosphates or sulphates), clogging the system. Many growers run separate stock tanks (often A and B tanks) and only combine them once diluted in the line. Check compatibility before mixing, and stay below solubility limits.
What units does this use?+
Enter the fertiliser amount and tank volume in your preferred units (for example kilograms and litres) and the injector ratio; the tool returns the stock concentration and the diluted concentration so you can confirm both the tank strength and what the crop actually receives. Pair it with the Fertigation and Hydroponic Nutrient calculators for full mixes.
Are the figures exact?+
The arithmetic is exact for the values entered, but real dosing depends on accurate injector calibration, full dissolution of the fertiliser, water quality and temperature. Calibrate the injector, check the actual ratio with a measured drawdown, and verify strength with an EC meter for reliable feeding.