Dose cal-hypo accurately for safer garden water. Compare targets and product strength quickly. Save results as CSV or PDF anytime.
Use this tool to estimate how much calcium hypochlorite product is needed to reach a target free chlorine level in water for garden tasks.
Free chlorine targets are usually expressed in ppm, where 1 ppm = 1 mg/L in water.
Strength is the available-chlorine fraction (example: 65% → 0.65). The “1000” converts mg to g.
These examples show typical calculations. Always verify with a test kit and adjust for real water demand.
| Volume | Current (ppm) | Target (ppm) | Strength (%) | Safety (%) | Dose (g) |
|---|---|---|---|---|---|
| 500 L | 0.0 | 2.0 | 65 | 10 | 1.692 |
| 1000 L | 0.5 | 2.0 | 70 | 0 | 2.143 |
| 200 US gal | 0.0 | 1.0 | 73 | 5 | 1.091 |
Doses are rounded. Teaspoon equivalents are approximate and not listed here.
Calcium hypochlorite is often used to sanitize stored irrigation water, flush drip lines, and reduce biofilm that can clog emitters. A controlled dose can lower algae pressure and odor in tanks, while keeping free chlorine within a range that is less likely to stress roots. The calculator helps you reach a target residual after accounting for current readings.
Start with the true water volume, including sump pits, header lines, and mixing totes. Measure current free chlorine with a reliable kit, then pick a target suited to the task: mild maintenance, shock sanitation, or line cleaning. Available chlorine percent on the label is critical, because different products deliver different strength per gram. For greenhouse recirculation, include reservoirs and return lines. For open ponds, estimate average depth carefully. If your test reads total chlorine, convert to free chlorine or set targets conservatively to start.
The dose is based on the ppm increase needed: target minus current. That ppm change is converted to milligrams of chlorine required for your volume, then adjusted by available chlorine to convert into grams of product. If you add a safety factor, the tool increases the dose to cover organic demand, dirty containers, and residual losses.
Dissolve granules in a separate bucket first, then add to the tank with agitation for uniform mixing. Allow contact time before irrigation or discharge; sanitation goals usually need more time than simple odor control. Re-test free chlorine after mixing, and top up in small steps rather than dumping a second full dose.
Avoid high-chlorine water on tender foliage, seedlings, and beneficial microbe programs. Keep pH in a practical range, because chlorine effectiveness and plant tolerance shift with pH. Store the product sealed and dry, never mix with acids or fertilizers, and rinse tools after use. Record doses and test results to refine your routine.
For routine tank maintenance, many growers aim for about 1–2 ppm free chlorine after mixing. For line sanitation, higher targets are used briefly, then flushed and re-tested before irrigating sensitive crops.
Available chlorine is the active strength of the product. A higher percent means you need fewer grams to reach the same ppm increase. Always use the label value for the batch you are using.
It is safer to pre-dissolve in a clean bucket and then add the solution while stirring. This reduces undissolved particles, improves uniform mixing, and helps you avoid hot spots of concentrated chlorine.
High organic load, algae, iron, and biofilm consume chlorine fast. Clean the tank, remove debris, and consider using a safety factor. Re-dose in small increments, testing between additions.
Sensitivity varies by species, growth stage, and root zone biology. Keep targets modest for living soils and young plants, avoid foliar contact, and flush lines after stronger sanitation treatments.
Store sealed, cool, and dry, away from acids, fuels, and fertilizers. Wear gloves and eye protection, avoid inhaling dust, and rinse tools after use. Never mix with incompatible chemicals.
Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.