01
The purpose
What does this calculator estimate?
How much algaecide for prevention or active treatment — by product type and pool size.
Water Chemistry · B11
Pool Algaecide Dosage Calculator
How much algaecide for prevention or active treatment — by product type and pool size.
Measure the inputsAlgaecide is a backup to chlorine, not a replacement — chlorine does the real sanitizing.
Read the full resultPolyquat (poly-60) won't foam or stain; cheaper poly-30 can foam at treatment doses.
Check the boundaryCopper algaecides work well but can stain surfaces and tint blond hair green at high doses.
Useful forWater ChemistryPlanningComparisonVerification
Live calculation
Algaecide dose
✓ Checked May 2026
Pick product type and whether you're preventing or treating.
Recommended dose
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Enter the required values to calculate.
Enter the known values. Let the engine handle the calculation.
✓ Formula checked↻ Live result○ No account needed
Planning estimate only. Confirm product labels, equipment specifications, qualified-professional advice and local requirements before acting.
The result, explained
Use the Pool Algaecide Dosage Calculator result with context.
How much algaecide for prevention or active treatment — by product type and pool size.
02
The tool
What information does it use?
- Pool volume: enter a measured or verified value
- Algaecide type: Polyquat (poly-60) is non-foaming and stain-free.
- Use: Maintenance dose vs active treatment dose.
03
The method
How to use this calculator
- Pool volumeEnter the value you can verify.
- Algaecide typePolyquat (poly-60) is non-foaming and stain-free.
- UseMaintenance dose vs active treatment dose.
04
The relationship
The formula in plain English
Dose = (Volume ÷ 10,000) × product base dose × use multiplier
Treatment doses are about double maintenance. Polyquat 60% is the cleanest all-round choice.05
Worked through
A worked example: 20,000 gal pool, weekly polyquat-60 maintenance
- Base dose poly-60 maintenance = 2 fl oz per 10,000 gal
- Dose = (20,000 ÷ 10,000) × 2 fl oz = 4 fl oz
- Add weekly after the chlorine level is normal
| Pool volume | Maintenance dose | Treatment dose |
|---|---|---|
| 5,000 gal | 1 fl oz | 2 fl oz |
| 10,000 gal | 2 fl oz | 4 fl oz |
| 15,000 gal | 3 fl oz | 6 fl oz |
| 20,000 gal | 4 fl oz | 8 fl oz |
| 25,000 gal | 5 fl oz | 10 fl oz |
| 30,000 gal | 6 fl oz | 12 fl oz |
06
Why it matters
How the result supports the next decision
Algaecide is a backup to chlorine, not a replacement — chlorine does the real sanitizing.
Polyquat (poly-60) won't foam or stain; cheaper poly-30 can foam at treatment doses.
07
Good inputs
Improve the estimate before relying on it
- Algaecide is a backup to chlorine, not a replacement — chlorine does the real sanitizing.
- Polyquat (poly-60) won't foam or stain; cheaper poly-30 can foam at treatment doses.
- Copper algaecides work well but can stain surfaces and tint blond hair green at high doses.
- Add algaecide after shocking has dropped — high chlorine degrades many algaecides on contact.
- Run the pump and brush surfaces after dosing to spread algaecide into corners and steps.
08
The boundary
How to interpret the result
Follow the product label, add chemicals separately and retest before another dose.
The engine reports invalid inputs and safety warnings beside the result. Resolve those messages before using the estimate.
09
Before acting
What should override this estimate?
- Measured site conditions and current test results
- Product labels and manufacturer specifications
- Qualified-professional advice and applicable local codes
10
Common questions
Frequently asked questions
Does algaecide replace chlorine?
No. Algaecide is a preventive backup that stops algae from establishing, but chlorine is your primary sanitizer. A pool with no chlorine will eventually grow algae no matter how much algaecide you add. Use them together, not one instead of the other.
Which algaecide is best?
Polyquat (polyquaternium, often sold as poly-60) is the best all-round choice — it doesn't foam, doesn't stain, and is compatible with all surfaces. Copper algaecides are effective and longer-lasting but carry a staining and hair-tinting risk if overdosed.
When should I add algaecide?
Add a maintenance dose weekly during swim season, and after every shock treatment once the chlorine has come back down. The post-shock window is ideal because high chlorine breaks down many algaecides before they can work.
Why is my algaecide foaming?
Cheaper poly-30 algaecides foam, especially at treatment doses or with aeration features running. Switch to poly-60, which is concentrated and non-foaming, or reduce the dose. Persistent foam can also indicate over-dosing.
How much algaecide for a green pool?
Algaecide alone won't clear an established green pool — that needs a chlorine SLAM. Use a treatment-strength algaecide dose as a follow-up after the water clears to prevent regrowth, not as the primary cure.
How often should I add algaecide?
A maintenance dose weekly in summer, plus after each shock once chlorine drops back to normal.
Can you put too much algaecide in a pool?
Yes — overdosing causes foaming (polyquat) or staining (copper). Stick to the label and the calculated dose.
Does algaecide work without chlorine?
Not well. It slows algae but can't sanitize; chlorine must do the main work.
Primary sources
Use the result with current guidance.
These official references support safe planning context. Product labels, local requirements and qualified-professional advice take priority over a general calculator estimate.