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Should You Add Pool Chemicals to the Skimmer?

Keeping your pool free from algae is a never-ending task. But no sooner have you got it just right than you test the water and find that the pH is off. Worst of all is when you go away for a few days and come back with a greenish tinge… it’s enough to make a grown man cry.

You’ll find that there are differences of opinion amongst pool experts regarding the best way to add chemicals to your pool. Is it OK to add chemicals to the skimmer? Or is there a better way?

As a general rule, it’s best not to add chemicals to the skimmer. Many pool chemicals are strong. Without dilution, these chemicals can damage metal, plastic, and rubber components in your pool. For safety, I generally pour mixed chemicals with pool water to dilute them and pour them into the path of the return water entering the pool.

There are exceptions, though, and different ways to handle different chemicals.

Let’s look at the typical chemicals you’ll add to your pool one-by-one and answer if it’s safe to add them to your skimmer.

Side Note: A question that sometimes comes up is Can You Put Chlorine Granules or Tablets in the Pump Basket?

Swimming pool skimmer box

Is It OK to Add Liquid Chlorine to the Skimmer?

Adding liquid chlorine to your skimmer is not advised. Rather pour the correct amount of chlorine into a 5-gallon bucket half-full of pool water (2 gallons at least). Stir it up so that it mixes well. Then walk around the edge of the pool pouring the mixture into the stream of circulating water.

It’s best to avoid pouring the undiluted chlorine into the pool as it can damage the pool surface, especially in the shallow end.

Spreading the chlorine around the edge of the entire pool ensures that you get the best coverage.

One of the more popular liquid chlorines available for shock treating pools is HTH Super Shock. It is best to premix it with some pool water before introducing it into the pool. You can get it here:

HTH Super Shock Treatment
  • Increases chlorine level
  • Kills bacteria & algae
  • Effective for all swimming pool types
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Is It OK to Add Trichlor to the Skimmer?

It is not recommended that you add trichlor to the skimmer. Trichlor comes in tablet form and the concentrated chlorine and cyanuric acid are best added via a chlorinator (chlorine feeder) or using a chlorine floater.

As the chlorinator is a built-in part of the system, you should switch off the pump before opening the lid to add the trichlor.

In the Swim supply 10, 20, and 50-pound buckets of 99% trichlor. The tablets are the thickest on the market and are perfect for automated chlorinator use. You can get the product here:

In The Swim Chlorine Tablets (Trichlor)
  • Keeps swimming pool water clean and sanitary 
  • Each tablet is sun-stabilized
  • Helps avoid inconsistent chlorination

Is It OK to Add Dichlor to the Skimmer?

Dichlor granules or powder can be added to the skimmer safely. Make sure the pump is running so the water is flowing through the skimmer. The small grains quickly dissolve, so there’s no need to first dissolve them in water before adding them to the skimmer.

You could also add dichlor to a bucket with pool water in it, stir, then pour around the outside of the pool or near a return jet.

A cost-effective product is In The Swim’s Sodium Di-Chlor Chlorine Granular Pool Shock is ideal for treating algae blooms and removing unwanted bacteria from your pool.

In The Swim Chlorine Granules (calcium hypochlorite)
  • Great for regular chlorination or shocking
  • Quickly eliminates algae, bacteria, & other harmful contaminants
  • Can be used in swimming pools, spas, and hot tubs

Is It OK to Add Cal-Hypo to the Skimmer?

Cal-hypo tablets or powder should only not be added to a skimmer basket. Cal-hypo is a strong form of chlorine and also leaves behind calcium. The calcium can cause scale on other pool equipment. Also, concentrated chlorine can damage rubber, metal, and plastic pool components.

In addition to this, calcium hypochlorite takes a while to dissolve fully.

It’s best to dissolve cal-hypo in a bucket of water first if using granules. Then pour around the pool. If using tablets, use a cal-hypo chlorinator (chlorine feeder), or a floater.

You don’t want this chlorine making contact with the bottom of your pool as it can stain or damage the surface.

In addition, before using cal-hypo, check your pool’s calcium levels. Using cal-hypo will introduce additional calcium into the water.

Caution: Never add cal-hypo tablets to a chlorinator or floater that has had other types of chlorine in it. It could cause a dangerous reaction.

Is It OK to Add Muriatic Acid to the Skimmer?

It is not advisable to add muriatic acid to your skimmer. The concentrated acid will damage your equipment and metal surfaces, so it’s best to dilute it first at a ratio of 10:1. Fill a bucket with at least 2-3 gallons of pool water and pour in the correct quantity of acid. Then pour the mixture around the edge of the pool.

You’ll probably have to repeat the process a few times to add sufficient acid to the pool water in the correct ratio.

The biggest risk with adding muriatic acid to the skimmer is damage to the rubber pump seals and to cartridge filters. Subjecting a cartridge filter to muriatic acid without degreasing it first can ruin the filter paper. It causes hardening.

Avoid breathing in the fumes as they are toxic. You also don’t want to let any of the acid splash onto your clothing, skin, or pool surfaces. The acid burns and will leave unsightly marks on the pool tiles and cement. You want to avoid burning your skin or your clothing.

It’s a good idea to wear suitable eye protection as any acid splashing into your eyes could damage them severely.

Acid Blue Muriatic Acid is a well-priced option if you need to reduce your pool’s pH.

Acid Blue Muriatic Acid by CPDI
  • Controls the pH level of water in swimming pools & hot tubs
  • Brightens concrete & masonry surfaces
  • Reduces up to 90% of harmful vapors

If you’re not sure how to use muriatic acid to lower your pool’s pH, check out this article: How to Lower the pH in your Pool

Is It OK to Add Sodium Bisulfate to the Skimmer?

Sodium bisulfate is a dry acid and should not be added to the skimmer. It is an acid that is used in place of muriatic acid to reduce the pH of your pool water. It’s best to mix up a dose with some pool water in a half-filled 5-gallon bucket first. You then add it to your pool by pouring it around the edges of the pool or preferably at the return jet.

Pouring it into a stream of moving water helps to spread the acid evenly around the pool.

EcoClean Solutions supplies sodium bisulfate in a convenient 25-pound pail.

EcoClean Solutions pH Reducer
  • Lowers pH
  • For pool, spas & hot tubs
  • Granular biodegradable & non-toxic form

Is It OK to Add Algaecides to the Skimmer?

It is not advisable to pour algaecides into your skimmer. The best way to introduce the liquid algicide into your pool is directly over the return jet. This ensures that the algaecide is evenly distributed around your pool.

HTH Super Algae Guard is a popular choice and will help ensure that your pool is algae-free year-round.

HTH Super Algaecide
  • Kills and prevents all algae types
  • Great for vinyl-lined and salt water pool systems
  • Non-foaming algaecide 

Is It OK to Add Borates to the Skimmer?

The answer to whether you should add borates to the skimmer is yes and no. You should ideally mix at least half of your borates with pool water in a bucket and then pour it around the edges of the pool.

Once that’s done, then you can take the remainder of the dose and pour it into the skimmer basket. You need to ensure that the pump is running while you dose the pool and then keep it running for the next 24-48 hours.

The recommended solution is using BORAX 20 Mule Team, which you can find in the laundry aisle as well.

Borax 20 Mule
  • Helps remove stains
  • Buffers & stabilizes pH
  • Neutralizes odors
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Is It OK to Add Soda Ash to the Skimmer?

To raise your pH or alkalinity, you can add soda ash to your pool, but do not add it directly in the skimmer basket. To correctly dose your pool, mix the soda ash with 2-3 gallons of pool water.

Stir the mixture until the soda ash has completely dissolved and then pour it around the perimeter of your pool. To avoid clouding your pool, avoid pouring the soda ash directly into the skimmer basket.

Soda ash won’t damage your pool deck or cement, so just wash any splashes off with a little water from your garden hose.

Try Cesco Soda Ash if you need to raise your pool’s alkalinity.

Cesco Soda Ash (pH Increaser)
  • Natural and non-toxic
  • Increases pool pH levels
  • Can be used as a water softener
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Is It OK to Add Baking Soda to the Skimmer?

It is not advisable to add baking soda to the skimmer in your pool. Doing so will cause clouding.

It is better to mix the baking soda with 2-3 gallons of pool water until it is fully dissolved. Then pour the mixture around the edge of the pool.

This Milliard Sodium Bicarbonate will help to reduce the alkalinity in your pool.

Milliard Baking Soda
  • No additives or preservatives
  • pH buffer in swimming pools
  • Increases alkalinity & pH
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Is It OK to Add Cyanuric Acid to the Skimmer?

It is perfectly fine to add cyanuric acid to the skimmer basket. Once you have calculated how much cyanuric acid you need to stabilize the chlorine, pour it into the skimmer basket.

Introduce one scoop (2 ounces) at a time into the skimmer while the pump is running. When all the acid granules have been added, use your hand to stir the remaining granules inside the basket. This gives the acid a chance to dissolve and enter the system.

Puri Tech Stabilizer is ideal for protecting the chlorine in your pool from UV radiation.

PuriTech Stabilizer Conditioner (CYA)
  • Safeguards pool chlorine from sunlight degradation
  • 100% cyanuric acid (cya)
  • Stabilizer/water conditioner

We also have a detailed article on when and how to add pool chemicals. You may want to check it out here.

Related Reading:
Can You Add a Skimmer to Intex Above Ground Pools?
How Do You Know If Pool Pump Shaft Seal Is Bad?

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