Pool Clarifier - What Is It? How Do I Use It? Complete Guide

Pool clarifiers are a type of pool chemical that are recommended to pool owners who are suffering from cloudy water that won’t clear up on its own.

If your water chemistry is otherwise fine, but your filter doesn’t seem to be able to get rid of the cloudiness on its own, it’s time to try some clarifier.

Typically a last resort after unsanitary conditions and chemical imbalances have been treated, clarifiers can help you remove debris that is too small for your filter to pick up.

In this article, we will discuss pool clarifiers, how they work, and the differences between clarifiers and flocculants. We’ve also included instructions for how to use clarifiers, as well as our top recommendations for clarifying products. Let’s jump in!

What Are Clarifiers?

Pool clarifiers belong to a group of products known as water clarifying agents. These products work to remove small particles of debris in your pool that can be very difficult for your filter to capture on its own.

Clarifiers are best known for restoring water clarity in cloudy pools where other treatment methods may have failed.

Cloudy water can be the result of many different pool conditions, such as a pH or alkalinity imbalance, an algae bloom, an overabundance of calcium, or growing bacteria.

In cases where shock products and balancing your other chemicals fails to make cloudy pool water clear, clarifiers work by coagulating tiny particles of pollution into larger clumps, which helps your filter to remove them from the water.

Some clarifiers are also available in tablet form, and are aimed towards being used as a preventative product. When placed into skimmer baskets, these clarifying tablets slowly release clarifying agent into the water, increasing the effectiveness of your filter.

How Do Clarifiers Work?

Pool clarifiers can be thought of as a glue-like substance, causing tiny particles of debris that are present in your water to stick together and form small clumps.

Without clarifiers, this superfine debris would be too tiny to be caught by your filter at all, creating an ongoing problem where the particles circulate through your pump, filter and back into the pool endlessly.

Once you add clarifier to the water, the tiny particles of debris react with the clarifier and form small clumps. However, these clumps are not dense enough to sink to the bottom of the pool, so they remain floating in the water column.

Over time, usually within the course of a few days, your filter will work to remove these small clumps of debris and your pool will return to its former clarity.

Clarifiers vs. Flocculants: The Pros and Cons

Pool flocculants are very similar in nature to clarifiers. As with clarifiers, flocculants also cause superfine particles of debris to stick together in clumps, however, flocculants themselves are much stronger than clarifiers.

It may help to imagine that flocculants are much more sticky in nature than clarifiers, so even though they work in the same way, they form much larger clumps.

The clumps formed by clarifiers are intended to be made large enough to be removed by your filter system.

But when using a flocculant, these clumps of debris become very heavy and fall to the bottom of your pool. The waste that accumulates on the bottom of your pool must then be removed by vacuuming, because it is too thick for filter systems to process.

While clarifiers are intended for mild to moderate problems in water clarity that involve tiny particles of debris, flocculants are capable of handling problems ranging from more moderate to severe.

Flocculants are often used to recover pools in areas where storm surges and other extreme flooding has taken place, and are capable of helping you remove much more dirt and debris from your pool than clarifiers.

Clarifiers can take days to work because your filter has to run constantly to slowly remove the coagulated debris. And, if too much gets caught in your filter, you may need to backwash your filter multiple times before your pool can become clean.

If you don’t have too severe of a problem, clarifiers are the best option for pool owners looking for less manual labour.

On the other hand, flocculants tend to work much faster than clarifiers. Even if your pool’s condition is not severe or muddy, flocculants have a more immediate effect on water clarity, and the cleaning process can be completed in as little as seven hours depending on your choice of product.

Find out more over at our guide on flocculants vs clarifiers.

How To Use Clarifiers

Step 1 - Balance Water Chemistry

Before using a clarifier, it is important to rule out certain other causes of cloudy water such as bacterial or algal blooms and chlorine or pH imbalances.

You can use a test kit to make sure your pool's chemical levels are within the appropriate operating ranges. Take any necessary steps to restore your pool’s pH, total alkalinity, and calcium hardness to ideal levels.

Clarifiers only work if your water cloudiness is caused by tiny debris particles, and will not address any other causes.

Before using a clarifier, you will want to ensure that your pool has a pH reading that falls between 7.4-7.6, and total alkalinity levels ranging from 80-120 parts per million (ppm).

Step 2 - Shock Treatment

If you have not done so during your treatment process already, you should also perform a shock treatment on your pool to eliminate any potential bacterial or algal blooms that may be occuring.

Use this pool shock calculator work out an appropriate dose.

You should then wait at least 24 hours after performing a shock treatment on your pool before continuing with a clarifier.

Step 3 - Turn On Pump & Filter

When adding a clarifier, your pump and filter should be left running constantly until your pool is clear.

If your pump was previously shut off for any amount of time, we recommend circulating your water for at least an hour before adding your clarifier so that debris does not form larger clumps than intended.

Step 4 - Calculate Clarifier Dose

To add a clarifier, find the ideal dosage based on the volume of your pool. Because clarifiers are available in many different strengths, you should always check the label information provided by your product manufacturer to determine the correct amount to use.

Step 5 - Add Clarifier To Pool

Distribute the calculated dose of clarifier around the perimeter of your pool.

Step 6 - Monitor Pump & Filter

Keep an eye on your filter and pump unit during the debris removal period. Check for signs that your filter may be getting clogged, such as slowly rising pressure drop over the filter.

If you suspect that your filter is becoming clogged, shut off your pump for as small of a period as possible in order to backwash or rinse your filter.

Our top recommendation for pool water clarifier is Algon Pool Clarifier. Available in a 1L jug, this product will effectively fix your cloudy water without causing any of the undesirable changes in the pH level of your pool that may occur with other clarifiers.

In pools with less severe conditions, this clarifier can allow you to achieve noticeably clearer water in as little as 48 hours.

Sometimes, clarifying products are used as preventative agents. Our favourite clarifier for preventing cloudy pool water is Crystal Cube Plus Floc Blocks, which are small clarifier tablets that can be placed within your pool’s skimmer basket.

These blocks work by slowly releasing small amounts of clarifier over time, helping your filter capture more of the particles that are flowing through your pump system.

An added bonus of the Floc Blocks is that they also contain phosphate removing agents. Because a buildup of phosphates can increase the likelihood of bacteria and algae developing in your pool, this is an excellent feature to have combined with a slow release clarifier.


If you have been dealing with incurably cloudy pool water, a pool clarifier may be just what you need.

Capable of handling all of the tiny particles in your water that other treatment methods leave untouched, clarifiers work with your pool’s existing filter system to remove debris in your pool water.

We recommend clarifiers for those with cloudy pool water that is not considered severe. If your pool water is significantly more dirty than cloudy, or can even be considered so white as to be milky, you may want to consider the use of a flocculant for more effective results.

Although clarifiers can assist with clearing up dirtier water, this is not their primary purpose, so multiple treatments and prolonged treatment times should be expected when using them for this cause.

Do you have any questions about pool clarifiers or how to use them? Leave us a comment in the below, we’d love to help!

Louis from Pool Advisor


A chemical engineer by trade, Louis is committed to debunking myths in the pool industry by explaining the underlying chemistry and making it accessible to all.