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How To Lower pH and Alkalinity in Your Pool

Your pool’s pH and alkalinity are typically tied together. When the pH goes up, the alkalinity follows close behind. While this pairing can be convenient, it also means you have to focus on reducing two parts of the chemistry with every adjustment. Adjusting these factors incorrectly can mess up the pool’s clarity and cleanliness.

To lower the pH and alkalinity in your pool, follow these steps:

  • Test the pH and alkalinity
  • Dilute dry acid
  • Use liquid pool acid
  • Check the pool’s chemicals
  • Get rid of the algae
  • Lower the pool’s salinity
  • Consider natural alternatives

Throughout this article, I’ll explain the whole process of testing and adjusting your pool’s pH and alkalinity. I’ll also dive into a few alternative options to prevent excessive chemical usage.

Test the pH and Alkalinity

It’s always important to test your pool’s chemistry before adjusting anything. Everything that lowers the pH will lower the alkalinity, and vice versa. Use test strips, digital testers, and liquid drops to find out if you need to adjust your pool’s chemistry. Unbalanced pH and alkalinity are dangerous because they can cause corrosion, buildup, cloudiness, and more.

The Poolmaster Chemical Testing Kit comes with everything you need to check your pool’s alkalinity and pH. You can also check the chlorine, bromine, and acid demand. These liquid drops provide top-notch accuracy that you won’t find in traditional pool test strips. The reagent bottles last much longer, too.

Keep these three things in mind when testing the pool’s pH and alkalinity:

  1. Your pool’s pH should be between 7.2 to 7.8, and the alkalinity should range from 80ppm to 120ppm. Don’t adjust these components if they’re both within the recommended range.
  2. Make sure your test strips or liquid reagents aren’t expired. They shouldn’t be discolored or dull. Always store your pool test kits in a dry, room temperature location. Direct sunlight can cause irreversible damage that renders them useless.
  3. Always add the smallest recommended dose of dry acid or liquid acid. The last thing you want is to drop the pH or alkalinity too low. You’d have to use soda ash or baking soda to bring them back to the recommended range.

Use Diluted Dry Acid

A dry acid is a budget-friendly option for those with soft-side pools or hot tubs. You can use dry acid with any pool material, making it better for people who have vinyl or fiberglass swimming pools. It’s important to dilute the dry acid if you want to prevent it from clumping. These clumps take much longer to dissolve and can damage the pool or spa.

Using dry acid is one of the best ways to lower the alkalinity in a pool. Not only does it work in small doses, but you also don’t have to worry about using corrosive liquid acid. Dry acid has numerous perks over liquid acid, all of which I’ll explain below.

  • Dry acid can be purchased in bulk. Most stores and online locations can’t sell more than a few gallons of liquid acid at a time due to legal reasons. However, you can purchase and store hundreds of pounds of dry acid at a time. You’ll save a lot more money in the long run with dry acid.
  • It’s not as dangerous as handling muriatic acid. Liquid acid is notorious for corroding metal, burning skin, and scorching hair. However, you won’t find any of these issues when handling dry acid for short periods of time. You can quickly clean spilled dry acid without corroding the ground, too.
  • Dry acid won’t explode or off-gas when exposed to warm sheds and direct sunlight. Liquid acid can’t get too hot, or the gallon containers will split or explode. This acid sends toxic fumes into the air. If dry acid gets too hot, all you have to do is move it to a colder location.

EcoClean Solutions’ Dry Acid is easy to use and comes with more than enough dry acid for multiple swimming seasons. It comes in 25-pound and 50-pound buckets. Ten pounds of this dry acid is equal to one gallon of top-tier muriatic acid. These buckets include a helpful dosage charge to keep your pool’s pH and alkalinity aligned.

EcoClean Solutions’ Dry Acid

Try Small Doses of Muriatic Acid

Despite some of the warnings in the previous section, muriatic acid is the most effective way to reduce your pool’s pH and alkalinity. Not only does it not need to be dissolved, but it’s also much stronger than dry acid. One gallon goes much further than one pound of dry acid. You can pour it directly into the pool and check the pH and alkalinity a few hours later.

Here are a few tips for using liquid acid:

  • Pour the acid around the edges to evenly distribute it.
  • Always run the pump for at least two to six hours after adding the acid.
  • Store pool acid in a room temperature location out of direct sunlight (sheds, garages, etc.).
  • I recommend wearing safety gloves and safety glasses when using liquid acid.

Check Your Pool Chemicals’ pH and Alkalinity

All pool chemicals have varying pH levels. Since the pH affects the alkalinity, everything you put in the water will influence both factors. Some pool liner materials impact the pH, too. I suggest steering clear of any chemicals that can increase the pH or alkalinity until you have both of them corrected.

So, how do your pool’s chemicals affect the pH and alkalinity?

  • Cyanuric acid reduces the pH because it’s an acid.
  • Chlorine tablets increase the pH, whereas liquid chlorine lowers the pH.
  • Muriatic acid and dry acid reduce the pH.
  • Soda ash and baking soda increase the pH and alkalinity.
  • Calcium hardness increases both of these factors.
  • Algaecides can reduce or increase the pH and alkalinity, depending on the primary active ingredient.

I typically recommend the pH and alkalinity before changing anything else in the pool’s chemistry. Every pool chemical works better within the suggested ranges, so there’s no point in adding anything else until they’re balanced.

Remove Algae Blooms From the Pool

Algae typically raises the pH and alkalinity. However, debris that causes algae blooms can raise or lower the pH. For example, most fertilizers, leaves, and other natural debris are acidic. They’ll drop the pH, but the incoming algae blooms might raise it beyond safe levels. The good news is you can quickly adjust the alkalinity and pH by dealing with the algae problem.

Try this quick method to stop algae from raising the pool’s pH and alkaline levels:

  1. Circulate the pool pump for as long as possible. Moving water mixes the chemicals and reduces the chance of algae sticking to the walls.
  2. Keep the pool’s chlorine between 5ppm to 6ppm. Algae blooms can’t survive and spread if there’s enough chlorine in the pool.
  3. Use an algaecide with chlorine. Algaecides prevent algae from growing while chlorine battles it.
  4. Brush and vacuum the algae. Stirring the algae and removing it from the pool prevent it from spreading to other areas.
  5. Use a water clarifier. Pool clarifiers clump algae in the filter, helping you remove it when you clean or backwash the filter.

Not only does algae influence the pool’s chemistry, but it also creates a hazardous swimming environment. Never swim in a green pool or in a pool with black algae spots. This algae digs into the pores of the plaster, making it difficult to remove.

Lower the Pool’s Salt Levels

Pool salt is one of the many things that cause a high pH in your swimming pool. A saline pool can create scaling, calcium buildup, stains, and many other issues. If you have a saltwater pool, I recommend keeping plenty of dry acid or liquid acid on hand. You’ll likely have to reduce the pH once every week or two.

Almost all swimming pools have salt in them, even non-saltwater pools. Salt comes from various pool chemicals with a sodium base (such as liquid chlorine). You can have a little bit of salt in a swimming pool without any issues, but it can’t exceed 1000ppm. A saline chlorinated pool will get cloudy and drastically increase the pH.

Unfortunately, dilution is the only way to lower your pool’s salt levels. You’ll have to turn off the pump, drain a foot of water, and fill the pool with fresh water. Circulate the pump for a few hours, then test the salinity.

Keep in mind that adding fresh water to the swimming pool will impact the pH and alkalinity. Most garden hoses have a slightly high pH, which means you might still have to add acid. However, you won’t have to worry about the salt increasing either factor once you partially drain and refill the pool.

Consider Natural Alternatives

There are several natural ways to lower a pool’s pH and alkalinity. Below, I’ll provide a brief list of options.

  • Lemon juice
  • Rainwater
  • Injected carbon dioxide
  • Distilled water
  • White vinegar
  • Apple cider vinegar

Always check your pool’s required dosage before adding any natural solution to adjust the water’s chemistry.

Author

  • Jonah Ryan

    Jonah has worked for several years in the swimming pool industry installing and repairing equipment, treating pools with chemicals, and fixing damaged liners. He also has plumbing and electrical experience with air conditioning, ceiling fans, boilers, and more. When he's not writing for Temperature Master, he's usually writing for his own websites, LawnCareLessons.com and DIYByHand.com.

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