Swimming Pool Clarifier: What It Is & Why It Matters


by Rick Patterson

There’s nothing worse than coming out for a nice Saturday morning swim and finding murky pool water… What a downer.

Or perhaps you’ve had your pool closed all winter and can’t wait for that first swim of the season. Bam! Cloudy water or even worse: algae. Yuck.

Don’t lose heart. Although cloudy pools are the worst, the good news is that there’s a simple fix that may just require a couple of checks and a magical potion I like to call: pool clarifier.

Today we’re going to cover everything you need to know about cloudy water and how to solve that pesky problem. 

What on Earth is Pool Clarifier?

Clarifier is a concentrated chemical substance that condenses the tiny particles and bacteria in your pool into larger clumps that can be easily picked up by your pool filter. We’re talking about minute particles that are too small for your filter to catch or to be picked up in your skimmer.

Pool clarifiers are products full of polymers that act as coagulants on foreign particles floating in the water. If you want to get scientific about it, when you pour clarifier into your pool, you’re adding positively charged ions to the water.

Almost like tiny magnets in your pool, these positive ions are attracted to the negative charge in suspended particles, thereby causing them to form clumps that can then be filtered out by the pool’s filtration system.

But wait! You’ve heard of clarifier before from some pool guy you talked to. He also mentioned some crazy “f” word (no, not that one) that was supposed to clear the water in your pool. So, which is it? Clarifier or flocculant?

What’s the Difference Between Flocculant and Clarifier?

Flocculant and clarifier have similar functions so there may be some confusion here. Let’s clarify:

  • Both of them bind to suspended debris, oils, scum, and excess metals that may be lurking in your pool.
  • Clarifier clumps them together and leaves them floating on top to be absorbed by the pool’s filter.
  • Flocculant (or pool floc) grabs all the cloudy-causing particles in your pool, bundles them together, and sinks them to the bottom

Top versus bottom; simple as that.

The main difference comes in when you have to get those clumps out of your pool. Whereas clarifier brings the particle clumps to the top and leaves your pool filter to do the heavy-lifting, floc requires some elbow grease on your part. 

Once you’ve added flocculant to your pool, you’re left with a ton of clumpy gunk on the floor of your gorgeous pool. Yuck. From here, it has to be vacuumed up. By you. Yep, that’s where we come to the downside of floc. 

Flocculant works really fast, but… it requires a bit more effort on your part. In fact, you actually can’t even use an automatic vacuum for this one. You have to do it manually on “waste” mode, which means you’ll be removing water from your pool. 

The real advantage of flocculant is its speed in de-clouding your pool. If you don’t have days to wait for clarifier to work, you should definitely give floc a try. Whether you’re planning a pool party for the next day or just don’t like to wait, using floc will be your best bet.

There you have it: fast-acting flocculant with added manual labor versus slower-acting clarifier with no work on your part. The choice is yours.

Why Should You Use Clarifier At All?

It may not seem like the worst idea to swim in a cloudy pool but it actually could be dangerous (and let’s face it, kinda gross).

Depending on what is causing the murkiness in your pool, there are some very good reasons to clear it up before your next pool party:

  1. Prevent water-related illnesses: Cloudy, dirty, or otherwise unclean pool water could be hiding some seriously nasty stuff. According to the Centers for Disease Control and Prevention (CDC), E. Coli and Giardia are two of the most common bacteria found in cloudy pools and can cause diarrhea, pink eye, ear infections, and respiratory infections.
  2. Environmental health and general appearance: Dirty or contaminated water attracts mosquitoes (and other pests) carrying deadly diseases that could affect you and your family. Not to mention a cloudy, green pool does nothing for your property value (or popularity in the neighborhood).
  3. Swimmer safety: Murky water and low-visibility increase the risk of pool-related accidents or drowning. Imagine jumping in and hitting someone who is swimming underwater or worse, not being able to see someone who needs help beneath the surface.

Why Your Pool Water May Be Cloudy

“But I take such good care of my pool!” You might say, “I don’t know why it’s cloudy… help!”

Don’t panic, it’s only natural that pool water will become cloudy on occasion. It’s not the end of the world and there are many reasons why it may have happened, through no fault of your own.

Often, cloudiness in pools is caused by a lack of water sanitizers, like chlorine. So if you’ve tested your chlorine and ruled that out, it could be due to all sorts of particles introduced to your pool in a variety of ways:

  • Sunscreen or body lotion from swimmers
  • Pet dander from your family dog swimming in the pool
  • Algae growth (bacteria and sunlight, the combo of doom)
  • Dirt, mud, or dust particles in the air
  • Organic material (such as leaves, grass, or flowers)
  • Recent rains or water runoff

If it’s not any of these, there may be other reasons your pool water isn’t clear and sparkling:

  • A chemical imbalance: The pH of your pool water might be off due to an excess or lack of chemicals. 
  • A broken, clogged, or malfunctioning pool filter: If your pool filter is clogged, worn out, or just plain broken, the water in your pool is not being cleaned or circulated properly.

So now that we’ve ruled out all of the possible reasons for cloudy pool water…

It’s Time To Clarify

Pool clarifiers are not meant to be used all season but can be a lifesaver in the great battles with cloudy water.

The absolute best time to use a pool clarifier is at the beginning of the swimming season. When you first open your pool after its long winter nap, you may find that it’s become a bit murky since your last swim. 

Another great time to pull out the clarifier is after you’ve had an unfortunate algae bloom… yep, heat and sun will do that.  Clarifiers take a bit of time to work but are so easy, it’s hard to imagine not trying them first.

Okay, you may be thinking, “I’m convinced! I need clarifier and I need it now! But how do I use it?” 

I thought you’d never ask.

How to Use Pool Clarifier (In 3 Easy Steps)

  1. Make sure your pool is pH balanced
  2. Follow the manufacturer’s instructions regarding amounts of clarifier to add
  3. Run your pool filter 24/7 until the water is clear

Use as directed! Maybe you’re impatient like me and want to see immediate results. Take a deep breath and go watch Netflix. It’s not going to change before your eyes and you may not be able to resist adding more. Don’t do it. Hide the bottle if you have to. Exceeding the prescribed dosage can actually increase cloudiness and you’ll just have to start all over.

Clarifier makes your pool filter more effective in doing its job. So, not surprisingly then, you’ll need to keep your pool filter running a lot after you’ve used clarifier. To be exact, you should run your pool 24 hours a day until your pool water is clear.

Does Pool Clarifier Always Work?

Pool clarifiers are not magic although they have been described that way in certain product reviews. 

Q: What is pool clarifier? Isn’t it suspect that manufacturers shroud the product in mystery?
A: It clears the water by magic.

Hocus pocus aside, your pool filter is the main component that works to keep your pool clean and clear.

When you use clarifier, however, you’re actually helping your pool filter work more efficiently. This, in turn, extends the life of your pool filter since it’s not having to work so hard to do its job.

Balance It Out Then Mix It Up

To get the best results from pool clarifier on the first try, make sure your pool filter is in tip-top-shape, that you’ve checked your pool chemistry, and that your pH and chlorine levels are in the right place.

Now you can add the clarifier and go for a swim!

Actually swimming in your pool while the filter is on will improve the effectiveness of the clarifier! When you are swimming, you’re kicking and splashing and getting all of those icky particles off the bottom of the pool. By doing this, your skimmer can grab the clumpy bits more easily.

I recommend pool volleyball and Marco Polo to really mix things up in the pool.

What To Do If It Doesn’t

So days have passed and you don’t see a difference. You’ve done everything right, but your pool is still cloudy… not to worry. Not all hope is lost.

If the chemistry in your pool is right then the clarifier will work. You may just need to recheck a few things and try again later. Here are some reasons the clarifier didn’t take on the first try:

  • Chlorine: Recheck your chlorine levels and make sure they are not too weak or too strong. We’re looking for a Goldilocks level here.
  • Filtration problems: I know you already checked it, but do me a favor and check it again. If your filter isn’t functioning at its best, it may be time to have it serviced. 
  • Too much calcium:  Do you have hard water? Calcium buildup will keep your water looking cloudy and cause damage to your pool filter and plumbing. Muriatic acid is your best bet to clear up this scaly problem.

Remember that although clarifiers take more time, they also require a lot less work on your part. Be patient, recheck these steps, and you’ll be well on your way to a crystal clear pool in no time.

Our Top 3 Picks for Best Pool Clarifiers 

Product #1:

Robarb 71205 Super Blue Swimming...
Robarb 71205 Super Blue Swimming...
  • Concentrated Formula - Only 1 oz. treats 5,000...
  • Clears cloudy water fast & prevents future hazy...
  • Effective at varying temperature levels & range of...

Robarb Super Blue Clarifier produces and maintains crystal clear pool water without affecting pH balance or other chemicals. Its thick, highly concentrated formulation works to clear cloudy water in any type of pool or spa without having to pre-shock the water.


  • Only 1 oz. is needed to clear 5,000 gallons of water
  • Effective at a large temperature range and with a variety of other chemicals present
  • Works with all filter types & will not clog filters
  • Reduces sanitizer (chlorine) demand by removing dirt particles


  • Takes a long time to work, which means running your filter longer 
  • May not work for algae growth

Product #2:

Clorox Pool&Spa Super Water...
Clorox Pool&Spa Super Water...
  • Concentrated pool clarifier to clear dull, hazy or...
  • Creates crystal clear pool water
  • Combines Small particles into large ones for easy...

Clorox Pool & Spa Super Water Clarifier works fast to keep your pool water clear and sparkling all year long. Its concentrated formula actually works well on algae growth too! The product includes an app that keeps track of all the usage details so you don’t have to.


  • Very concentrated formula: Only 1 oz. is needed to clear 5,000 gallons of water
  • Safe for all pool types
  • Inexpensive product from a Clorox, a trusted name in cleaning products


  • Best if used weekly, which means lots of bottles
  • May cause foaming (bubbles) in the pool

Product #3:

Tidal Vision Crystal Clarity —...
Tidal Vision Crystal Clarity —...
  • All Natural Concentrated Pool and Spa Clarifier,...
  • Binds to suspended debris, oils, scum, and excess...
  • Chitosan is non-toxic, environmentally safe, and...

Tidal Vision Crystal Clarity Pool & Spa Clarifer is an all-natural clarifier that works with all types of sanitizers, is biodegradable, and environmentally safe. Its formulation contains chitosan that actually helps to keep your filter clear with each and every use.


  • All Natural Pool and Spa Clarifier
  • Contains chitosan that works to keep your filter clear
  • Non-toxic, environmentally safe, and biodegradable
  • No added dyes or fragrances


  • May not work as effectively in saltwater pools
  • May take repeated usage to notice a big difference


There you have it: everything you need to know about pool clarifiers and why they can be so beneficial for your pool care regimen. The battles with algae and cloudy water rage on, but now you’re properly armed to fight the good fight.

Happy Swimming!

Categories: Pool Care, Pool Chemistry