How do you calculate flocculant dose for a pool?

Multiply your water volume in 10,000-gallon units by the label's fl oz per 10k gal rate, then by any allowed severity factor. For a 20,000-gallon pool (2.0 basis) at 8 fl oz per 10k gal with a 1x factor, that's 2 x 8 x 1 = 16 fl oz.

How much flocculant do I add to a 20,000 gallon pool?

Using a typical label rate of 8 fl oz per 10,000 gallons, a 20,000-gallon pool (2.0 basis) needs about 16 fl oz of flocculant for a standard clearing treatment.

What is a good flocculant dose?

A good dose is exactly what the label specifies for your gallonage, usually 4 to 16 fl oz per 10k gal. More is not better; excess floc creates a sticky layer that is hard to vacuum and can foul cartridges.

Flocculant vs clarifier, which do I use?

Flocculant forms large heavy clumps that sink and are vacuumed to waste, clearing severe cloudiness fast. Clarifier makes small clumps the filter catches over days. Use floc for heavy haze or dead-algae recovery; clarifier for routine polishing.

Can I double the flocculant dose for very cloudy water?

Only if the product label explicitly permits a higher rate, that is what the severity factor is for. Doubling an unpermitted dose risks a gel layer that clogs the filter and wastes product without clearing faster.

Why is my pool still cloudy after flocculant?

Common causes are too little settling time, running the filter in 'recirculate' or 'filter' instead of letting particles settle then vacuuming to waste, or an under-dose. Recheck volume and label rate before adding more.

Pool, Spa & Water Treatment Chemistry calculator

Pool Flocculant Dose Calculator

Flocculant (floc) is a coagulant that binds fine suspended particles into heavier clumps so they sink to the pool floor and can be vacuumed to waste. This calculator converts your pool volume and the product label's dose rate into the exact fluid ounces to add, with an optional severity factor for badly cloudy or green-recovery water. Pool service techs and pool owners use it because floc is unforgiving: under-dose and the water stays milky, over-dose and you waste product and risk a gummy residue that clogs the filter. Getting the fl oz right the first time saves a full re-treat and another day of downtime.

What this calculator does

Estimate flocculant dose from water volume, product rate, and treatment severity.
Use it for severe cloudy-water cleanup when vacuum-to-waste and filtration plans are ready.
It calculates the total fluid ounces of flocculant to add by multiplying water volume (in 10k-gal units) by the label dose rate and any permitted severity multiplier.

Formula used

Flocculant dose = volume basis x label dose rate x severity factor x adjustment

Inputs explained

Water volume to treat (gallons / 10,000): Enter gallons divided by 10000.
Label dose rate for flocculant: Use product label directions.
Cloudiness severity factor: Use 1 for normal label dose or a labeled multiplier if allowed.
Label-permitted dose adjustment: Use 1.0 for standard label dose. Use a labeled multiplier only if specifically permitted on the product label.

How to use the result

Use it before a floc-and-vac treatment on cloudy, dead-algae, or post-shock water where the filter alone will not clear the haze.
Floc requires the filter valve set to 'waste' (or the pump off overnight then vacuum to waste), this calculator sizes the dose but assumes you follow the label's circulation and settling procedure, which varies by product.

Current U.S. benchmarks

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Common questions

How do you calculate flocculant dose for a pool? Multiply your water volume in 10,000-gallon units by the label's fl oz per 10k gal rate, then by any allowed severity factor. For a 20,000-gallon pool (2.0 basis) at 8 fl oz per 10k gal with a 1x factor, that's 2 x 8 x 1 = 16 fl oz.
How much flocculant do I add to a 20,000 gallon pool? Using a typical label rate of 8 fl oz per 10,000 gallons, a 20,000-gallon pool (2.0 basis) needs about 16 fl oz of flocculant for a standard clearing treatment.
What is a good flocculant dose? A good dose is exactly what the label specifies for your gallonage, usually 4 to 16 fl oz per 10k gal. More is not better; excess floc creates a sticky layer that is hard to vacuum and can foul cartridges.
Flocculant vs clarifier, which do I use? Flocculant forms large heavy clumps that sink and are vacuumed to waste, clearing severe cloudiness fast. Clarifier makes small clumps the filter catches over days. Use floc for heavy haze or dead-algae recovery; clarifier for routine polishing.
Can I double the flocculant dose for very cloudy water? Only if the product label explicitly permits a higher rate, that is what the severity factor is for. Doubling an unpermitted dose risks a gel layer that clogs the filter and wastes product without clearing faster.

Last reviewed 2026-05-12.