Flocculant to clean swimming pools

How To Clear Your Pool With Flocculant [Guide]

Depending on how well your pool care is going, you might already know about this magical product called pool flocculant. Or if you’re just hearing of it for the first time, it’s probably because you’re having an issue with cloudy water in your pool.

In this guide, we’ll give you the lowdown on what pool flocculant is, how to use it (with instructions), what to do when it seems to be not working, and some hot tips for handling this agent for pool cleaning.

In this guide, we’ll cover:

What is Pool Flocculant?

Pool flocculant, or as we Kiwis like to call it, “floc”, is a very special chemical that every pool owner should have handy in their garden shed. Pool flocculant makes cloudy pool water clean and clear again.

It essentially gathers together all the small floating specks in your pool that are not heavy enough to sink by themselves. Then it bundles them together, and sends them down to the bottom of the pool. We want these deposits at the bottom of the pool so that they can be cleaned by a pool vacuum.

Think of it as dusting the corners of your windows or wiping away a few stray cobwebs to make your house that much cleaner. What are in these “cobwebs”? Mostly bacteria, algae spores, viruses, and other microscopic particles (harder to see than other debris).

The whole point of floc is just getting these microparticles in a place where they can be removed from the pool. Floccing is not difficult but can sometimes be frustrating. For this reason we’re here to talk you through how to successfully add flocculant to clean your pool.

Comparison between Flocculant and Clarifier


  • contains polymers that clump together the small particles that cloud up your pool. 
  • these particles are then big enough to be caught by the pool filter. 
  • after the filter captures them, you’ll need to clean your pool filter. 
Clarifier pros:
  1. fixes mild cloudiness. 
  2. saves water. 
  3. can be used anytime for a clean water boost. 
Clarifier cons:
  1. works slowly, could take days depending on how cloudy it is.
  2. pool filter needs cleaning afterwards. 
When to use clarifier:

When you’ve just opened your pool or it’s looking a bit cloudy at any point. 


  • similarly to clarifier, floc combines the small particles into heavier, larger loads, like pool cobwebs. 
  • these cobwebs are then heavy enough to sink to the bottom, instead of being captured by the pool filter. 
Flocculant pros:
  1. it works quickly, in a mater of hours. 
  2. it’s effective – no particles get left behind. 
  3. ideal for sand and DE filters, which are the most common in New Zealand. 
Flocculant cons:
  1. can’t be used with cartridge filters. 
  2. requires more work – vacuuming afterwards, when it has resettled. 
  3. when vacuuming it loses pool water. 
When to use flocculant:

When you want to clear your pool ASAP for a party, and have time for vacuuming. 

In Which Cases You should consider to use Flocculant

When You’re in a Fix

The main motivation for using floc is when you need to clear your cloudy pool ASAP, because you’re planning to use it very soon! Floc works well in a matter of hours. It’s extremely effective and will have your pool cloud-free again in no time.

But before you run off to pour it into your pool, wait! There’s a second part to it!

You’ll need to vacuum afterwards. Those newly-formed pool cobwebs will sink to the bottom and sit there, ruining your swimming view. Make sure you have time to vacuum your pool to complete the process.

While we highly recommend robotic vacuum cleaners over manual vacuum cleaners, for the sake of saving time, water and electricity, in the case of an easy floc fix, manual vacuuming is definitely the way to go!

As Part of a Deep Clean

It’s true, you can use flocculant even when it doesn’t look like you need it, just for that extra sparkly water effect. You’ll know from our Guide to Pool Maintenance that there are three main steps to cleaning your pool:

  1. Skimming the surface.
  2. Brushing your pool.
  3. Vacuuming your pool.

If you’re wanting to add ‘floccing’ to this process, do so between brushing your pool and vacuuming your pool (seeing as you have to vacuum as part of the process anyway).

Let’s dive into what exactly the process is.

How To Use Flocculant

First! Get your hands on some flocculant product. Flocculant can come in granular or liquid forms. We recommend Focus Quick Floc Clarifier or Focus Granular Pool Floc.

Step by Step use of Flocculant

  1. Turn the filter to the ‘Recirculate’ setting.
  2. Make sure the pH level in your pool is balanced (between 7.4 and 7.6).
  3. Read instructions on your package of flocculant. You’ll have to add the correct amount according to the volume of your pool.
  4. Once added, run the pool pump for two hours to properly circulate it and evenly distribute it.
  5. Turn off the pump and leave the pool water to sit for 8 hours.
  6. After 8 hours, turn your filter setting to ‘Waste’, because now it’s time to vacuum the pool and remove the dirty deposits (pool cobwebs) from the bottom.
  7. Check the pool water level. It will have gone down, because you’re vacuuming to ‘waste’, meaning you are removing water from the pool. Use a garden hose to refill your pool, and then re-balance your water chemistry.

Our Pool Floc Hot Tips

  1. Floccing is best done in the evening: you can add the floc, run the pump for 2 hours, then leave it for 8 hours overnight and vacuum the next morning. Have a pool party on Saturday? Do the floccing on Friday night and you’ll have sparkly water by the time your guests arrive.
  2. Vacuum slowly! The movement of the vacuum will stir up the deposits. To prevent them from floating again (and being inaccessible to the vacuum), be gentle with the vacuum head. You can even vacuum twice to be sure to catch everything.
  3. Usually while vacuuming to ‘Waste’, you can run the garden hose into the pool to keep the water level the same. But when vacuuming after floccing, we recommend topping the water up afterwards, as the inflow of water will also disturb the debris at the bottom.

How Long Does Pool Flocculant Take to Work?

Pool floccing is generally not a last-minute activityYes, it’s quick. But it’s 24-hours kind of quick.

It needs 2 hours with the pool pump on, and at least 8 hours with the pump off. Then the pool needs to be vacuumed. It’s a quicker fix than a whole deep clean, but it still takes a little foresight and planning ahead.

As soon as you have vacuumed and re-balanced the water chemistry, your pool is good to go again!

How Much Floc is Too Much Floc?

Uh-oh. This seems to be a common search. The amount of flocculant that your pool needs depends on a few things, like:

  • Your pH level, so it’s important to balance it first.
  • The volume of water in your pool.
  • The type or brand of flocculant you are using.

Using more floc than necessary can make your pool look even cloudier, hence why some people get frustrated with this product.

So, how do you calculate the correct amount of floc for your pool?

We recommend using a pool calculator to work out how much water is in your pool, or contacting your pool specialist who’ll be able to tell you based on a few key details.

The amount of floc that needs to be mixed is based on how much water is in your pool. Be sure to calculate carefully, otherwise you might join the frustrated floccers of the internet!

How to Get Floc Out of Pool

Too much flocculant means that it will start to stick to itself over and above the bacteria and algae spores that we’re trying to clear. The issue with this happening is that it won’t sink to the bottom. It’ll stay floating in your pool and start to cause more problems, like clogging your pool filter.

If you’ve gotten a bit too excited while adding the floc, leave the pool alone for a few more days to give it more undisturbed time to sink to the bottom. It’s recommended not to swim when the floc is in the pool. As you can imagine, it’s not so pleasant and might irritate your skin.

Vacuum again after a few days, even several times if needed, to clear up the debris that have hopefully settled by now. If this is still not working, you’ll have to empty the pool and refill it to start again.

Common Problems with Pool Flocculant

Pool floc not sinking?

Wait longer! If 8 hours didn’t cut it, leave it for 48 instead. By then the deposits (‘cobwebs’) should have settled at the bottom, ready for you to vacuum up.

Also check that you definitely turned the pump off after 2 hours. Pool water needs to be still in order for the floc to sink.

Pool still cloudy after floc?

Hmm, there might be a few other issues at play here.

  • Check that your pump and filters are clean enough and working properly.
  • There might be environmental factors that are continuously adding to your pool’s cloudiness! Check the surrounding pollen levels, and debris like dust, sunscreen and human contaminants.
  • There could also be too many chemicals in your pool in which you would need to re-balance the pool and start over. Check with your pool pro first.

Pool floc not working?

If this floccing product isn’t doing what you want it to do, there’s a good chance something has gone wrong along the way. If it’s not sinking, or the pool water is still cloudy, read the answers above.

If you still think something is off, check that you’ve added the correct amount of floc according to your pool’s volume, and speak to a professional if you need to.

Pool floc got you flapping?

We’re here to give you the confidence that you need when it comes to pool floccing. With a little expert advice, you’ll be clearing the clouds in your pool like a pro and telling all your BBQ friends about the wonders of pool flocculant in no time.

Happy Floccing!

About the author
Adrian Hill
Adrian Hill

Hey! I'm Adrian, founder and pool expert here at Dolphin Pacific. I love spending time with family, fishing, and have been known to brew my own beer.

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