Which Chemical Should I Put in the Pool First?

Pool chemicals turn your swimming pool from a health hazard to a haven for aquaventure and leisurely swimming. While freshwater might be great for an initial dip, draining 15,000 gallons of water regularly to replace water can be pretty harmful to the environment and your wallet. And that’s why you not only need to use pool chemicals but also need to use them in the right quantities.

The chemicals you need to put first are Muriatic Acid and Sodium Bicarbonate. These will help balance the alkalinity and the pH of water, after which you should add Calcium Chloride to balance the water’s hardness. Finally, you’ll add Chlorine to make your pool water microbially inert. 

In this article, you will learn how to add different chemicals and the recommended quantities for each, including:

  • Muriatic acid
  • Sodium Bicarbonate (Baking Soda)
  • Calcium Chloride
  • Chlorine

Add Muriatic Acid to Increase Acidity

ff by adding muriatic acid and increasing the acidity of your swimming pool. Though it might sound counterproductive, you need to raise the acidity to kill mold, remove rust stains and hardened calcium deposits. 

Though none of these are immediate threats to a freshly opened pool, starting with muriatic acid sets the correct sequence of chemicals for your pool. Make sure that you do not add too much muriatic acid. Remember that a quart of acid can typically suffice for 15,000 gallons of water (the size of a standard inground pool).

Add Soda Ash to Balance Alkalinity

You may have killed off most of the bacteria in the pool in the previous step, but you’ve also turned the water acidic. And because acidic water is corrosive, you cannot swim in it, making it necessary first to balance its alkalinity. Adding any chemical with high net-alkalinity will balance the water’s alkalinity and make it less corrosive. 

However, different chemicals can have their own side effects, and it is advisable to go by the tried and tested sodium bicarbonate as it is tried and tested. Getting a serving from your local chemist is no different than ordering baking soda online. Get a can of sodium Bicarbonate and start adding it in small portions while testing the water’s alkalinity.

Balance pH of the Water

This step is only different in concept because, in practice, the actions that balance alkalinity also balance pH. That’s because acidic water has a pH below 7, whereas alkaline water has a pH above the 7 point mark. When you add baking soda to offset the water’s acidity, you’re also balancing its pH. 

The only difference is that you now measure its pH as well. Alkalinity is easy to go overboard with. A net alkaline solution, the bare minimum required from the previous step, can easily be unfit to swim in if the pH is past 7.9. You should aim for a 7.4 pH level as it is barely alkaline and well-balanced for human eyes and mucous membranes, making the water safe to swim in for a longer period.

Offset Calcium Hardness Imbalance

This is the second-last step in getting your pool ready for swimming. The goal of balancing calcium hardness in your pool is to make sure the water in your pool isn’t too hard or too soft. If the water is too soft (has low calcium hardness), it can cause corrosion across the interior of your pool and in the lining of the circulation pipes. 

Calcium chloride can help harden the water, but you must take very tiny steps in raising water’s hardness as it becomes nearly impossible to soften hard water without having to add more water; a luxury most pools don’t have since they’re already full when you’re adding chemicals. Hard water can leave your skin dry and produce curds out of any oils or sanitizing material you’re using. 

As a result, you can have blocked pores that generally lead to acne. This step might seem unforgiving because both soft water and hard water have their pros and cons, but you have relatively a broad safe range for Calcium hardness, with anything between 200 to 400 ppm (parts per million) being acceptable for a swimming pool.

Shock Your Pool With Chlorine

If you’ve previously held even tangential interest in swimming, you know that Chlorine is (usually) essential for swimming pools as it helps keep the water microbially inert and acts as an algaecide while also sanitizing the water to a large extent. Using chlorine tablets and a tablet dispenser like Swim Time Chlorine Dispenser can help evenly distribute the chemical in your pool while ensuring its longevity. 

Remember, Chlorine reacts due to sunlight and can disappear from water. This means the frequency with which this step will need to be repeated depends entirely on how much sunlight your region receives. If you use chlorine powder, I recommend using a stabilizing agent like Clorox Chlorine stabilizer, which helps lengthen the lifespan of dissolved chlorine powder. Chlorine powder is easier to use because it has been the industry standard and therefore has better usage guidelines. 

For instance, it is common knowledge that you only need one pound of Chlorine for every 10,000 gallons of water. Given that a standard inground pool generally contains 15,000 gallons of water, one can safely assume an initial chlorine deposit requirement of 1.5 lbs. 

How Do You Balance the Chemicals in Your Pool?

The difference between a pool that’s ready for swimming and a chemical soup is simply whether you’ve used the right quantities and balanced them against each other. This would be impossible without using precise testing and monitoring. 

Since the chemical composition can change and you need to add chemicals periodically, you’ll need to test your swimming pool regularly. Here are some products that will help you maintain the health, readiness, and acceptability of your swimming pools.

JNW Direct Pool and Spa Test Strips

This is your all-in-one water-testing kit that allows you to check whether your water’s Chlorine, pH, alkalinity, and hardness are up to optimum levels. Each strip serves seven functions, and a detailed usage guide is included in the packaging, making the product novice-friendly. With over 7,000 ratings and reviews, the product stands at a global average rating of 4.5 out of 5 stars. 

Embryant pH Meter

While testing strips are great, you may not want to run out of them by checking pH regularly. Still, a regular checkup of your swimming pool’s pH levels is essential. That’s why I recommend a pH tester with a digital screen. 

You can use this and take a few different readings of water from your swimming pool by scooping the water in a glass and dunking the reader’s testing end into the glass. You need to take multiple readings because, despite circulation, the chemical in the water may not be distributed evenly at the point you take your initial sample from.

Final Thoughts

The sequence with which you add chemicals doesn’t make or break your pool. Therefore, you have room for error as long as you ultimately balance the pH and the water hardness. The above order is simply the best way to achieve the desired balance without wasting too much of each chemical in the process.

Jed Arnold

Jed spent every year from the ages of 15 - 22 as a Lifeguard (Red Cross) and ages of 17 - 22 as a Certified Pool Operator (CPO). Between working for over a dozen facilities and owning a pool, he carries over a decade of pool experience.

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