The Difference Between Pool Clarifier and Flocculant

At Swim University, we are really big fans of flocculant, which we use when we have to clear up our pools really fast. However, flocculants aren’t always the chemical of choice when it comes to clearing up a swimming pool.

We would like to explain the difference between your basic pool clarifiers and flocculants, and let you know when and how to use each one.

The Difference Between Pool Clarifier and Flocculant

What is a Swimming Pool Clarifier?

When it comes to clearing up a swimming pool, your filter is the best man for the job. However, it shouldn’t be the ONLY man on the job.

Clarifiers help your pool filter pick up those tiny, little particles that are making your water cloudy. They do this by (nerd alert) coagulation. Meaning they take those tiny, little particles and bring them together to form bigger particles so that your filter has a better chance of catching them. This makes your filter more effective in clearing your swimming pool.

Kem-Tek 326-6 Pool and Spa Ultra Clarifier, 1 Quart
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The chemical is really simple to use. All you need to do is add a few ounces (depending on how many gallons your pool is) directly to your pool water every couple of days until the water is clear.

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Since it helps your pool filter do it’s job, you need your pool filter to run. We suggest that if you have a cloudy pool and you decide to use a clarifier, to run your pool 24 hours a day until your pool is clear.

Also, since your filter is doing the bulk of the work, you need to help it by getting those particles into the filter. Here are some basic tips to help your clarifier and your pool filter clear your pool more efficiently:

  1. Turn your main drains on: If you have a main drain at the bottom of your pool, make sure it’s turned on to allow the pool water from the bottom to get into your filter.
  2. If you don’t have a main drain, you can use your manual vacuum. Just hook it up, as if you were going to vacuum, and leave it turned upside down at the bottom of your pool. Here’s how to set up your manual vacuum.
  3. Swim! Swimming helps kick up the particles off the bottom of the pool so that your skimmer can capture the cloudy water.
  4. If you have a sand filter, you can buy a filter enhancer, which allows sand filters to act like D.E. (Diatomaceous Earth) filters. This helps your sand filter to pick up smaller particles. I recommend using Bioguard’s Filter Enhancer called Sparkle Up. If you can’t find it, you can use a cup of plain D.E.. Just pour it into your skimmer and the D.E. will lay on top of your bed of sand helping to catch the smaller particles your sand filter might otherwise miss.

What is Swimming Pool Floc or Flocculant?

Pool floc or flocculant has become a fast favorite because…it’s fast!

The concept is simple. Floc takes all those particles that are making your water cloudy and sinks them to the bottom of your pool. Then, it will be YOUR job to vacuum them out. What’s great about this chemical is it acts fast, what sucks is, YOU have to do the work.

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An excellent chemical that allows all the particles in your pool to settle to the bottom so you can vacuum them out.

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Simply add the floc directly to the pool water and let your pool run for 2 hours (if you have a sand filter with a multi-port valve, turn it to recirculate).

After the pool runs for those 2 hours and the chemical has a chance mix into the water, shut the pool filter off completely for the next 8 hours. Make sure you don’t have a timer set; the pool must sit still for 8 hours. I would recommend doing this overnight.

The next morning, you will wake up and see a cloud at the bottom of your swimming pool.

Your job now it to get that cloud out of your pool. To do that, you need to hook up your manual vacuum. You cannot use an automatic cleaner for this job. Also, you need to vacuum your pool on waste. Meaning, you’ll be vacuuming the water OUT of your pool, so keep a garden hose in it to fill it with fresh water while you vacuum.

It may take a couple of times vacuuming. If your pool completely clouds up from moving the vacuum around, take a break and allow the particles to settle back to the bottom before continuing to vacuum.  If you do this, you can expect to have your pool clear in no time at all.

When To Use A Clarifier or Flocculant

The big difference between these two pool clearing methods is time. If you want your pool clear for a pool party you’re throwing soon, we suggest floccing. It’s fast, but it’s work (elbow grease).

If you just opened your pool or it’s just a little cloudy and you don’t mind swimming in cloudy water (perfectly safe BTW), then you can use a clarifier.

Clarifiers take time to work, but they are a LOT less work (elbow grease) on your part. Also, since you don’t have to vacuum your pool to “waste,” you will also save money on replenishing chemicals such as chlorine and pH…oh and water.

Now that you know the difference between the two, next time your water is cloudy, you will have the knowledge to choose which method is right for you.

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Happy Swimming!

The Difference Between Pool Clarifier and Flocculant

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  • Mke B

    Thank you the simpliest yet mostly clearly written explaination on the subject I have ever read. Finally get real answers that I can apply to my pool maintainence routine.

  • melinda forster

    amazingly well written and expalined .. you are the sole intelligent clear source on this matter

  • Bill Verkuilen

    Helpful info–if you happen to have a pool with a “vacuum to waste” option. But what’s the best way to use a floc if you have an above ground pool with no “vac to waste” option?? Would have been nice for the article to be a bit more all-inclusive of common pool setups.

  • Matt Giovanisci

    Thanks @melindaforster:disqus!

  • Matt Giovanisci

    You can vacuum to the waste/backwash port on your filter. Just keep it open when you’re vacuuming. All filters have a waste/drain/backwash port.

  • Roberto R

    Is “recirculate” the same as “backwash”? I have a sand filter but it doesn’t have a recirculate seeing. Just filter, backwash, rinse and waste.

  • Kelly Maurer

    Help. Floc worked great and cleared the water, but only have of the floc sank to the bottom of the pool. The other half is floating on the top of the water…..How do I remove that floc?

  • Kelly Maurer

    With an Intex cartridge pump, am thinking to unhook the hose that feeds in to the pool and allow it to drain while vacuuming. At least that is what I plan on doing. It will lose alot of water fast, so will do it in spurts of vacuuming and will be adding water with a hose while doing all of this. If a better idea….would love to read it.

  • Matt Giovanisci
  • bigproblem

    Hi. We use borehole water on our farm. The calcium content of the water is very high. Is there a way that I can remove the calcium from the water. A water softner won’t work as the pools size is in excess of 100 000 liter. Thanks

  • Matt Giovanisci

    Flocculant may do the trick for you, but the best way is to use fresh water with low calcium. I know that might be hard for you to do, but you can contact the fire department to see if they will fill your pool.

  • bigproblem

    Thanks Matt! Never thought of the fire department, but as our town’s water is also from underground, everybody in town battle with the same problem. Therefor I need to try the flocculant. What type of flocculant should/can I use? Thanks again for your time and suggestions.

  • Matt Giovanisci

    Any floc at your local store or online will work.

  • Gayan Demel

    Hello Friends,
    Can anyone help me how many Flocculant liters need to add in 700000 Liters swimming pool capacity of water? Pool water look to dirty, kinda cloudy, because of rain 2-3 days ago.

  • Matt Giovanisci

    The amounts directed should be on the back of the flocculant container.

  • Gayan Demel

    thank you very much

  • LemonadeMan

    Also relevant to the floccing is the area of the bottom of the pool.

  • Yvonne Martinez

    used a whole bottle of Floc in our 22,000 inground pool 3 days ago and it is still cloudy. Ph and TA was good when we added so I’m not sure what is happening?? Don’t know what to do next? Please help…

  • Christopher Petzold

    Once you use Floc all the cloudiness in the pool should settle on the bottom like a white powder. Give it time to work though. I usually do mine in the late afternoon and give it time to settle on the bottom before vacuuming the next day. From there you have to manually vacuum it out. Hook a vacuum line to your skimmer, close off the bottom drain, and set the filter setting on your pump to Waste so it doesn’t get recirculated back into the pool. Depending on the size of your pool and how much floc you have to vacuum out this can take awhile and you’ll have to refill your pool with water back to the skimmer level.

    Also if your PH and TA are good and you’re still getting algae in the pool you might be having problems with the CYA, or cyanuric acid. CYA acts as a stabilizer that protects the chlorine in your pool from being evaporated by the sun, but too much will cause the chlorine to “lock up” preventing it from killing the algae causing the greenness. Measure your CYA levels and if they are high the only way to lower them is to drain some of the pool water and replace it with fresh water (if you plan to vacuum the floc to waste you will lose a lot of water like this anyway and will kill two birds with one stone.) Don’t waste your time or money buying cya reducers at places like Leslie’s. I tried it last year and it did absolutely nothing.

    I hope this information helps. Good luck.

  • Yvonne Martinez

    When we called the pool store today they suggested adding another 5 pounds of shock and run filter over night to see if all the algea dies. Then said may need to floc again. We had it off for 4 days after the first dose of floc with no results. Would the CYA make the floc not work at all? After the shock do you think I should refloc or drain water or what?

  • Tbuck1

    How long do I need to wait to run the filter after I have used floc?

  • Matt Giovanisci

    When you add floc, you run the filter for 2 hours and shut it off. You can vacuum the cloud. When you’re done, you can turn the filter system back on.

  • RB

    We floced 2 days ago and this morning the pool was clear. When my husband vacuumed the pool, it got cloudy again. He ran the filter which didn’t clear it up. Should we floc again or will the sedaments settle again if we turn off the filter?

  • Matt Giovanisci

    It should settle again because there’s still floc in the water.

  • T.M.

    I have a 30,000 gal pool. It has been unused for a year or two by previous owners. It’s in ground with a vinyl liner. It has a sta rite cristal flo sand filter. I used a whole bottle of HTH floc last night, recirculated for 2 hours, and then let it sit for 12 hours. I have a film of brown patches cover the entire top of the water. Per my local pool store, my levels were the following.can you please help me.

    Saturation idx: 0.4
    TDS: 500
    CYA: 0
    Tot chlorine: 0.1
    Free chlorine: 0
    Ph: 8
    Tot alkalinity:106
    Adj. total alk: 106
    Tot. Hardness: 178
    Salt: n/a
    Copper: 0
    Iron: 0
    Manganese: no
    Hazy: no
    Cloudy: no
    Green/black/mustard algae: no
    Slime/ mold: no

  • Matt Giovanisci

    What do you need help with?

  • Aaron Fresinski

    It looks like it needs chlorine based on your readings and your water is extremely soft, stop adding scale remover. PH is also out of alignment as you typically don’t want this above 7.6. Shock your pool – I use Clorox pool shock as it does not impact PH and this will get the chlorine up. Add muratic acid to get the PH down….. Just might work out.

  • George

    Thank you for writing this article. It was very clear and to the point. I never even knew there was a difference between the two. Now I can make an informed decision.