Adding chemicals to your swimming pool: Timing and Techniques

Mark Larm Sep 17, 2023
609 People Read
Adding and testing chemicals to your swimming pool.

Disclosure: Some of the links in this article may be affiliate links, which can provide compensation to me at no cost to you if you decide to purchase. This site is not intended to provide financial advice and is for entertainment only. 

A detailed guide on when and how to add chemicals to your swimming pool.

Having a pristine swimming pool is the dream of every pool owner, and achieving that dream involves more than just water and a pool skimmer. Properly managing your pool's water chemistry is a vital aspect of pool maintenance. This comprehensive guide will equip you with in-depth knowledge and techniques for adding chemicals to your swimming pool at the right time and in the correct way. By the end of this guide, you'll be well-prepared to maintain a well-balanced and enjoyable pool all season long.

Understanding Pool Water Chemistry

Before we dive into the specifics of adding pool chemicals, let's establish a solid foundation by understanding the role of different chemicals in pool maintenance and the ideal ranges for key water parameters:

Ideal Water Chemistry Ranges:

  • pH: 7.2 to 7.8

  • Free Chlorine: 1.0 to 3.0 ppm

  • Total Alkalinity: 80 to 120 ppm

  • Calcium Hardness: 200 to 400 ppm

Finding out how many gallons of water are in your pool. Pool Water Calculator. pool water calculator

Water chemistry is dynamic and influenced by various factors such as weather, pool usage, and environmental conditions. Regular water testing is essential to ensure that these parameters stay within the desired ranges.

When to Add Specific Pool Chemicals

  • Chlorine and Sanitizers:

    • Routine Chlorination: To maintain free chlorine levels within the ideal range, consider using chlorine tablets, liquid chlorine, or salt chlorination systems. 

    • Salt cells are great but remember to keep all the pool chemicals balanced. The cell will not produce chlorine if there isn’t enough salt, too much salt, not enough conditioner, and the chlorine will just disappear. I've even heard that letting your phosphates go too high will stop it from working. WARNING, when your salt cell is not producing chlorine, your pool will go green fast. The salt is a TDS (total dissolved solid) and you will have to add 2x the amount of liquid chlorine to do the job until you can get it fixed.

    • Liquid chlorine is the best if you are adding chlorine yourself because it does not leave behind any waste products or raise your conditioner levels.

    • Chlorine tablets are great for the heat of summer but remember that they are a stabilized chlorine and will raise your cyanuric acid (conditioner) to a level so high that it turns into a TDS and kills your chlorine causing you to 2x the amount you need to use. In extreme cases it will turn your walls and pool cleaner purple, yes, I said purple. Not to worry because at this point the only thing to do is drain and refill your pool and the purple will dissolve back into the pool water. Reminder, don’t add any conditioner back into the pool until the purple is gone so you can get an accurate reading when adding the proper amount back in.

    • Shock Treatments: Shock treatments are your go-to solution for addressing issues like algae blooms, cloudy water, or high chlorine demand. Perform these treatments in the evening or at night to minimize chlorine loss due to sunlight. Please understand that that is something we say but it is not something to worry about. People on the internet act like you're just tossing money out by adding chlorine during the day and it won’t work. Well, I’ve been adding chlorine to pools in the heat of the day for over 18 years now and it seems to be working just fine. 

  • pH Adjustment:

    • Monitoring pH Levels: Regularly test and monitor pH levels, aiming to keep them within the recommended range.

    • Adding Acids or Bases: Adjust pH levels by carefully adding muriatic acid to lower pH or soda ash to raise it. When adding muriatic acid remember the rule of “always add chemicals to water, never water to chemicals.” It’s best practice to add the amount of acid that you need to a 5-gallon bucket with a couple of gallons of water in it and walk it around the deep end of the pool. Never add acid in one spot because it will go down in a coulomb and etch the plaster on the bottom. WARNING: acid gives off a fume that you mostly can’t see so if it’s not windy out try to not breathe right above the bucket. Always follow safety guidelines and adhere to manufacturer instructions.

    • Adding a Base means to raise pH. Increasers are usually soda ash or baking soda. Yes, just grab that old nasty box that is trying to keep your freezer fresh and toss it into the pool, broadcasting it over the top while the system is running. It’s probably time for a new box in the freezer anyway. Above-ground vinyl pools and fiberglass pools are pH neutral and rarely need to have the pH lowered. 

  • Alkalinity Management:

    • Understanding Total Alkalinity: Total alkalinity acts as a pH buffer, stabilizing pH levels.

    • Balancing Alkalinity: Adjust alkalinity by using alkalinity increasers to raise it or alkalinity decreasers to lower it as needed. 

  • Calcium Hardness:

    • Importance of Calcium Hardness: Proper calcium hardness levels are essential to protect pool surfaces.

    • Adjusting Calcium Hardness: Calcium hardness should be checked once every month or two. This is the trick to keeping calcium from building up on your tile line when it is too high and etching and eating your plaster when it is too low. When too low it will also ruin your vinyl liners and cause your fiberglass pools to turn chalky. Raise calcium hardness using calcium chloride or lower it by dilution with fresh water. Algaecides and Stain Preventatives:

    • Preventing Algae Growth: Use algaecides regularly to prevent algae infestations. I say to use algaecides when you are getting familiar with taking care of your pool, heck let’s face it, a lot of us are just lazy and want the easy way out. If that’s you just toss a PoolRx in the pump basket, fill the tab feeder and you're good to go. 

    • Managing Metal Stains and Scale: Choose stain and scale control products to prevent unsightly stains and scale buildup. Orenda has a product called “CS-1000 Stain and Metal Remover” that suspends the calcium hardness effectively removing it from the pool. 

Best Practices for Adding Pool Chemicals Warning when adding chemicals

A. Safety Precautions:

  • Personal Protective Equipment (PPE):
    Prioritizing safety begins with wearing the appropriate personal protective equipment (PPE) when handling pool chemicals. Here's why it's crucial:

    • Gloves: Always wear chemical-resistant gloves to protect your hands from direct contact with pool chemicals. These gloves are designed to prevent chemical penetration and skin irritation.

    • Eye Protection: Chemicals can splash or release fumes that may irritate or harm your eyes. Therefore, wearing safety goggles or protective eyewear is essential to safeguard your vision.

    • Respiratory Protection: In situations where you might be exposed to fumes or airborne particles, consider using a mask or respirator to protect your respiratory system.

  • PPE serves as your first line of defense against chemical exposure, ensuring your safety during chemical handling and application.

  • Proper Storage:
    Safe chemical storage is equally important as safe handling. Properly storing pool chemicals reduces the risk of accidents and chemical reactions. Here's what you need to know:

    • Designated Storage Area: Set aside a designated storage area specifically for pool chemicals. This area should be well-ventilated and isolated from the pool equipment and other chemicals.

    • Avoid Sunlight and Moisture: Keep chemicals away from direct sunlight and moisture, as exposure to these elements can degrade the chemicals and reduce their effectiveness. Consider using sealed, waterproof containers or chemical storage cabinets.

    • Temperature Control: Maintain a cool and dry environment. Fluctuations in temperature can affect the stability of chemicals. Avoid storing chemicals in extreme heat or cold.

    • Proper Labeling: Ensure all chemical containers are clearly labeled with their contents and usage instructions. This minimizes the risk of accidental mixing.

    • Keep Out of Reach: Store chemicals out of the reach of children and pets, preferably in a locked cabinet or shed.

  • Proper chemical storage is vital not only for your safety but also for the longevity and effectiveness of your pool chemicals.

B. Chemical Mixing and Dilution:

  • Guidelines for Dilution:
    Dilution is often necessary when dealing with concentrated pool chemicals. To ensure safe and effective dilution:

    • Follow Manufacturer Recommendations: Always adhere to the manufacturer's instructions for dilution ratios. These guidelines are designed to provide the optimal balance of chemical effectiveness and safety.

    • Use Clean Containers: When diluting chemicals, use clean containers, preferably ones dedicated to this purpose. Avoid using containers that may have previously held other substances to prevent contamination.

    • Stir or Mix Thoroughly: After adding the chemical to water, stir or mix the solution thoroughly to ensure even dilution. This prevents localized concentration and potential hazards. 

  • Avoiding Chemical Reactions:
    Mixing chemicals directly in your pool water is a recipe for disaster. To prevent unwanted chemical reactions:

    • Add Each Chemical Separately: Never mix chemicals directly with each other. Instead, add each chemical separately to the pool water. Allow time for each chemical to disperse and dissolve before adding the next one.

    • Maintain Adequate Water Circulation: Ensure that your pool's pump and filter system are running during chemical addition. This helps distribute chemicals evenly throughout the pool, reducing the risk of localized reactions.

C. Step-by-Step Chemical Addition:

  • Chlorine and Sanitizers:
    When adding chlorine and sanitizers to your pool, follow these steps:

    • Pool Skimmer: Never introduce chlorine products into the pool skimmer. Add your liquid chlorine by pouring the predetermined amount around the edge of the pool. Lower the gallon as close to the water as possible to avoid splashing. This method ensures even distribution. 

    • Dissolution in a Bucket: Alternatively, you can dissolve chlorine granules and powder in a bucket of water before pouring the solution into the pool. This method can be useful for shock treatments or when you need precise control over the chlorine dosage.

    • Chlorine Tablets: Should be added to a tab floater that should be tethered somewhere so it does not float on top of the step or Baha shelf when the pump turns off. The high acidity level will bleach and eventually dissolve the plaster on the steps. Warning; Do not use floaters in vinyl pools. When the pump is off and the floater stops moving the chlorine will continue to dissolve and go straight down and bleach the vinyl bottom.

  • pH Adjustment:
    When adjusting pH levels in your pool:

    • Running the Pump and Filter: Ensure that the pool's pump and filter system are running while adjusting pH. This promotes even distribution of the pH-adjusting chemicals.

    • Pour Slowly and Evenly: Slowly pour pH-adjusting chemicals around the pool, moving evenly to distribute them throughout the water. Avoid adding large quantities in one spot to prevent localized pH imbalances.

  • Alkalinity Management:
    When managing total alkalinity:

    • Even Distribution: Sprinkle alkalinity increasers or decreases evenly across the pool surface while the pump and filter system are running. This ensures uniform mixing.

  • Calcium Hardness:
    When adjusting calcium hardness levels:

    • Dissolve Calcium Chloride: Dissolve calcium chloride in a bucket of water before pouring it evenly across the pool surface. Warning; Calcium chloride when mixed in water will get hot and can cause problems in cheap flimsy buckets. It is best to add just a portion at a time while you learn this product. This step minimizes the risk of calcium hardness-related issues.

  • Algaecides and Stain Preventatives:
    When using algaecides and stain preventatives:

    • Follow Manufacturer Instructions: Always adhere to the manufacturer's recommended dosage and application method. Different products may have specific requirements for effectiveness. Some may say to apply evenly across the pool surface while others will want them added to the skimmer. Some will want the pool to be running for a few hours and some will want the circulation pump to run for up to 72 hours so make sure you read and follow directions.

By following these safety precautions and chemical addition techniques, you'll not only maintain a well-balanced pool but also ensure the safety of yourself, your family, and your pool guests. These practices are fundamental in achieving a pool that is not only beautiful but also safe to enjoy all season long.

D. Monitoring and Testing:

  • Regular Testing: Test your pool water routinely using a reliable test kit, test strips, or electronic tester.

  • Making Adjustments: Based on test results, make necessary chemical adjustments to keep water chemistry within recommended ranges.

Common Mistakes to Avoid

To ensure your pool maintenance efforts are successful, steer clear of these common pitfalls:

A. Overdosing or Underdosing: Measure chemicals accurately to prevent overtreating or undertreating your pool.

B. Ignoring Weather Conditions: Extreme weather can impact water chemistry; adjust your chemical treatment schedule accordingly. There is less chlorine in the colder months and more in the hotter months. 

C. Neglecting Pool Size and Capacity: Calculate chemical doses based on your pool's size and capacity to avoid overuse or underuse of chemicals. Don’t worry, you will get so familiar with your pool and what it takes that it will become an “old hat” for you. 

D. Neglecting the Pool's Circulation and Filtration System: Ensure that your pool's circulation and filtration system is running effectively to evenly distribute chemicals. Also, schedule your filter cleaning. I start with a minimum of 6 months and work from there. 4-5 months if you have dogs or live in a more desert area that gets lots of dirt blown in the pool. I consider filter cleaning a “Pool Hack” because the more neglected and dirtier your filter gets the more money you lose trying to stay ahead of the algae.

Troubleshooting Finding out water problems

Even with diligent maintenance, issues may arise. Here's how to troubleshoot common chemical imbalances and water quality problems:

A. How to Correct Common Chemical Imbalances: Learn how to adjust pH, chlorine levels, alkalinity, and calcium hardness to bring them back into the desired range. First things first, right? It doesn’t matter if you have cloudy water or start seeing algae, the first thing to do is get your chemicals balanced correctly then work on the problem. 

B. Dealing with Unexpected Water Quality Issues: Address cloudy water, algae blooms, or other water quality problems promptly by diagnosing and treating the underlying causes. 

Cloudy water: start by making sure your filter is clean by checking the pressure on the pressure gauge. To know where it should be, use a black Sharpie pen and mark the pressure gauge right after you clean the filter. Most guidelines say to clean the filter after the pressure rises by 10 psi. “Pool Hack,” never let it get that high, it will cost you money in extra chemicals and cost you time and frustration getting rid of algae all the time. If you're cleaning your filter, you're saving from $100-$150 every time, so feel good about keeping it clean, and don’t let it go up more than 3 psi. The next thing to do to clear up cloudy water is to add a clarifier to the pool while the pump is running. The trick to adding a clarifier is to read the label. Do not add too much or it will backfire and cause cloudiness. 

Algae Blooms: If you are new to pool cleaning or just fed up with problems learning about algaecides is a worthy task and will be worthy of another blog. Pick a favorite and dose it correctly. Too much of some can cause staining and other foaming. Warning: They don’t work alone; you must add chlorine. “Pool Hack,” once you get the idea of what water wants and give it to it then you should be able to wean yourself and your pool off of additives like algaecides. One algaecide I recommend starting with the PoolRx because it’s a set it and forget it for six months type.  

C. When to Seek Professional Help: If you encounter persistent or severe water quality issues, consider consulting a pool professional for expert guidance and assistance. It may even be time to drain and refill the pool. Check out this blog: "How often should you drain and refill your pool.” 


Maintaining the water chemistry in your swimming pool is a significant responsibility of pool ownership. By understanding when to add specific pool chemicals and adhering to best practices for chemical addition, you can enjoy a safe, clear, and inviting pool throughout the swimming season. Regular testing, precise dosing, and responsible chemical management are the keys to a well-balanced and enjoyable pool experience for you, your family, and your guests.

Disclosure:  Some of the links in this article may be affiliate links, which can provide compensation to me at no cost to you if you decide to purchase. This site is not intended to provide financial advice and is for entertainment only.