Fertigation Acid & Dose for Target pH
Clears drippers
Enter your water volume, starting and target pH and acid strength to get the pH drop and the acid to inject— so phosphates and micronutrients stay available and your drip lines stay clean.
Acidify irrigation water
Next: add about 1.5 L (1,500 mL) of acid to 10,000 L to drop pH from 7.5 to 6 — add it slowly, stir, and recheck pH with a meter before irrigating; always wear gloves and eye protection.
The strength factor is titration-specific to your acid type and water alkalinity; treat this as a starting estimate and confirm by titrating a sample, never the reverse — add acid to water, not water to acid.
Acid injection — key facts
- pH drop
- starting pH − target pH
- Target pH
- ≈ 5.5–6.5 for fertigation
- Dose scales with
- volume × drop × strength
- Common acids
- phosphoric, sulfuric, nitric
- Real driver
- water alkalinity buffers pH
- Safety
- always add acid to water
- Confirm
- measure pH at the emitter
- Privacy
- Runs in your browser; nothing uploaded
Tame alkaline water so nutrients flow, not clog
Alkaline irrigation water is a quiet drip-system killer: it lays down carbonate scale that blocks emitters and pushes phosphates and micronutrients out of solution just when the crop needs them. Injecting acid pulls the water pH down to roughly 5.5–6.5, keeping those nutrients soluble and the lines clean — but the right dose depends on the water's buffering, so a starting estimate plus a meter check is the way to do it.
This tool estimates the pH drop and the acid to inject in millilitres and litres from your water volume, starting and target pH and acid strength. Use it to set a dosing-pump rate, plan a line-cleaning flush, and keep fertigation effective. Always add acid to water and confirm at the emitter. Pair it with the Hydroponic Nutrient, Fertigation and Drip Chlorination tools for a complete water-and-feed plan.
Set the pump rate
Get a starting acid dose for target pH.
Keep nutrients available
Hold phosphates and micros in solution.
Protect the drip lines
Stop scale clogging emitters and tubing.
Dose it safely
Add acid to water; confirm at the emitter.
Frequently Asked Questions
Why inject acid into irrigation water?+
Most irrigation water is alkaline, which precipitates calcium and magnesium and lets phosphates and micronutrients lock up — clogging emitters and lowering nutrient availability. Injecting acid lowers the water pH to roughly 5.5–6.5, keeping those nutrients soluble, preventing scale and biofilm, and keeping drip lines and drippers flowing freely.
How is the acid dose calculated?+
The dose scales with the water volume, the size of the pH drop you want and the strength of your acid. The calculator estimates the millilitres of acid to inject for the target pH drop and converts it to litres for the whole batch. Because real water buffers differently, the result is a starting dose you then fine-tune with a meter.
What target pH should I aim for?+
For most fertigation a target of about 5.5–6.5 keeps phosphates and micronutrients available and protects the lines without going so low that it harms roots or equipment. Some growers dip lower briefly for a line-cleaning flush. Match the target to your crop, water and the nutrients you are injecting.
Which acid should I use?+
Common choices are phosphoric acid (which also supplies phosphorus), sulfuric acid (strong and cheap) and nitric acid (which also supplies nitrogen). Each has a different strength and safety profile, so set the acid-strength input to match your product. Choose based on cost, the nutrients you want to add, and what is safe to handle on your operation.
Why does water alkalinity matter more than pH?+
Alkalinity — the carbonates and bicarbonates in the water — is the buffer that resists pH change, so two waters at the same pH can need very different acid doses. High-alkalinity water needs much more acid to shift its pH. Where you have an alkalinity figure, use it to refine the dose; otherwise treat the result as a buffered estimate.
How do I dose and check it safely?+
Inject acid with a calibrated dosing pump into the irrigation stream, never the other way around, and always add acid to water — not water to acid. Wear eye and skin protection, run the system, then measure the pH at an emitter and adjust the rate until it holds at target. Re-check whenever the water source or fertiliser changes.
Will acid injection unclog existing drippers?+
A periodic acid flush at a lower pH can dissolve carbonate scale that has already built up in lines and emitters, restoring flow. Routine acidification to target pH then keeps new scale from forming. Combine with filtration and, where biofilm or algae are the problem, a separate chlorination treatment.
Is acid injection compatible with my fertilisers?+
Generally yes, and lower pH keeps many fertiliser nutrients more soluble — but avoid mixing concentrated acid directly with calcium- or sulphate-containing stock solutions, which can precipitate. Inject acid and incompatible fertilisers through separate lines or stagger them, and jar-test a mix before running it through the system.
Are the figures precise?+
They are a sound starting dose. The true acid needed depends on your water's alkalinity and temperature and the exact acid concentration, so always confirm with a pH meter at the emitter and adjust. Treat the calculator as a way to get close fast, then dial it in and re-check as conditions change.