Jar Test Stock Solution Calculator

Calculator

Stock source

Chemical mass dissolved

Use grams for prepared stock.

Final stock volume

Use milliliters.

Known concentration

Known concentration unit

Active purity

Enter percent active ingredient.

Working dilution factor

Use 1 for no dilution.

Jar sample volume

Use milliliters.

Target doses

Separate mg/L values with commas.

Replicates per dose

Pipette resolution

Smallest readable mL step.

Reserve volume

Percent extra working stock.

Single pipette limit

Formula Used

Prepared stock concentration: C_primary = mass(g) × 1,000,000 ÷ final volume(mL)

Known stock conversion: mg/mL × 1000, g/L × 1000, or % w/v × 10000 gives mg/L.

Active primary concentration: C_active = C_primary × purity ÷ 100

Working stock concentration: C_working = C_active ÷ dilution factor

Active chemical needed: mg needed = target dose(mg/L) × jar volume(L)

Stock aliquot: aliquot(mL) = target dose(mg/L) × jar volume(mL) ÷ C_working(mg/L)

Delivered dose: delivered dose = rounded aliquot(mL) × C_working(mg/L) ÷ jar volume(mL)

How to Use This Calculator

Select whether the stock is prepared from dry chemical or entered as a known concentration.
Enter stock preparation data, active purity, and any working dilution factor.
Enter jar volume and target jar test dose values in mg/L.
Add replicates, pipette resolution, reserve percentage, and single pipette limit.
Press Calculate to view aliquots, delivered doses, dosing errors, and statistics.
Use CSV for spreadsheets or PDF for a simple lab record.

Example Data Table

Input	Example Value	Meaning
Chemical mass	10 g	Dry chemical added to volumetric flask.
Final stock volume	1000 mL	Prepared primary stock volume.
Active purity	90%	Active chemical fraction.
Dilution factor	10	Primary stock diluted to working stock.
Jar volume	1000 mL	Water sample in each jar.
Target doses	10, 20, 30, 40, 50, 60	Trial dose range in mg/L.

Jar Test Stock Solution Planning

Jar testing helps a treatment team compare chemical doses before full scale feeding. A small stock solution is added to jars containing measured water samples. Each jar receives a different target dose. The calculator converts those targets into clear pipette volumes. It also corrects for purity, dilution, jar size, and pipette resolution. This keeps each trial repeatable and easier to document.

Why Stock Strength Matters

A weak stock needs large additions. A strong stock may need tiny additions that are hard to measure. Both cases can create dosing error. The best stock strength gives practical aliquots within the range of available pipettes. Operators often prepare a primary stock, then make a working dilution for the actual jar test. This page supports both prepared and known stock entries.

Purity, Dilution, and Dose Accuracy

Commercial chemicals are rarely one hundred percent active. Alum, ferric salts, polymers, lime, and powdered aids may include water, carriers, or inactive material. The active purity field adjusts the working concentration. The dilution factor handles a secondary dilution. For example, a one to ten dilution uses a factor of ten. The result table shows the exact aliquot, rounded aliquot, delivered dose, and error.

Statistical Review

Jar tests compare a set of doses, not one value alone. The summary reports count, mean dose, median dose, standard deviation, and dose range. These statistics help check whether the chosen series is balanced. A narrow series is useful near an expected optimum. A wide series is better for early screening. The total stock estimate includes replicates and reserve volume, so lab preparation is less rushed.

Practical Lab Notes

Use clean glassware and mix the stock fully. Label every jar before adding chemical. Add stock quickly and consistently. Start timing after each addition. Record pH, turbidity, floc size, settling time, and final clarity. Export the results as CSV for spreadsheets. Export the PDF for simple lab records.

Trial Spacing

Start with even dose steps when source water is unknown. After one run, center the next set around the clearest jar. Keep one low jar and one high jar for comparison. This approach shows trends, limits waste, and protects against a false optimum caused by mixing or measurement noise.

FAQs

What is a jar test stock solution?

It is a prepared chemical solution used to dose small water samples. It lets operators test coagulant, polymer, lime, or other treatment chemicals at controlled trial doses.

Why is active purity important?

Purity adjusts the concentration to the active ingredient only. If purity is ignored, the actual delivered dose may be lower than expected, especially for hydrated salts or commercial blends.

What does dilution factor mean?

Dilution factor describes how much the primary stock is diluted before use. A one to ten working dilution uses a factor of ten. No dilution uses one.

How is aliquot volume calculated?

The calculator multiplies target dose by jar volume. It then divides by working active stock concentration. The result is the stock volume added to each jar.

Why does rounded dose error appear?

Pipettes measure in fixed steps. The exact aliquot may not match a readable mark. Rounding creates a delivered dose that can be slightly higher or lower.

Can I use this for polymer dosing?

Yes. Enter the polymer stock strength, active purity, dilution factor, jar volume, and target doses. Use careful mixing because polymers can shear or hydrate slowly.

What should I enter for jar volume?

Enter the actual water volume in each jar, usually 500 mL, 1000 mL, or 2000 mL. The value must match your lab setup.

Why include dose statistics?

Statistics summarize the dose series. Mean, median, range, and standard deviation help review whether the selected trial spacing is narrow, broad, or balanced.

Jar Test Stock Solution Calculations