Having a high alkalinity level in your pool can make it difficult to properly balance and sanitize the water. While there are a few options for lowering alkalinity, some methods work faster than others. If you need to lower your pool’s alkalinity level quickly, here are some of the best options to consider.
Page Contents
- 1 Use Alkalinity Decreaser
- 2 Dilute the Pool Water
- 3 Use Muriatic Acid
- 4 Adjust Chlorine Levels
- 5 Use Baking Soda
- 6 Change the Water
- 7 Tips for Lowering Alkalinity Quickly
- 8 The Effect of High Alkalinity
- 9 Target Alkalinity Level
- 10 Lowering Alkalinity Without Chemicals
- 11 Preventing High Alkalinity
- 12 FAQs
- 13 Conclusion
Use Alkalinity Decreaser
The fastest way to lower alkalinity is by using a chemical alkalinity decreaser or reducer. Alkalinity decreasers contain sodium bisulfate, which reacts with bicarbonates in the water to lower total alkalinity levels. Look for an alkalinity decreaser product that is designed for swimming pools and follow the dosage recommendations on the label.
When adding an alkalinity decreaser, broadcast the recommended amount across the entire surface of the water. Run the pool pump and filtration system while adding the chemical so it can circulate and react with the bicarbonates thoroughly. Test the alkalinity level again after a few hours. You may need to add more decreaser in incremental doses to reach your target alkalinity reading.
Dilute the Pool Water
Another rapid way to lower high alkalinity levels is by diluting the pool water with fresh water. This decreases the concentration of bicarbonates and carbonates that contribute to total alkalinity. To dilute, you can add a large volume of fresh water from a garden hose. Aim for diluting the pool by 10-15%, then retest alkalinity.
Depending on how high your starting alkalinity level is, diluting by up to 20% may be necessary to achieve a significant drop in the reading. Be sure to retest for calcium hardness and other chemical levels after diluting, as those will decrease proportionately as well.
Use Muriatic Acid
Muriatic acid can also be used to lower alkalinity and pH quickly in a swimming pool. When adding muriatic acid, it reacts with carbonates and bicarbonates in the water to lower total alkalinity. Muriatic acid is very potent and dangerous if not handled properly.
Only add muriatic acid following the product instructions carefully. Wear safety goggles and gloves, and add the acid slowly in small doses. Broadcast around the perimeter of the pool as you add it. Retest every few hours and add small doses as needed to reach your target alkalinity level. Do not add too much at once, as lowering alkalinity excessively can damage the pool.
Adjust Chlorine Levels
Boosting the chlorine level in your pool can contribute to lowering alkalinity, especially if alkalinity is too high. As chlorine is added and becomes more concentrated in the water, it starts to react with bicarbonates and gradually reduces alkalinity levels. Running the pool pump and filter continuously will accelerate this process.
Test chlorine levels regularly as you raise it and add the appropriate chlorine products to reach 5-10 ppm. Shock the pool if necessary to rapidly get free chlorine levels up. High chlorine combined with circulation for 24-48 hours can start to bring down elevated alkalinity.
Use Baking Soda
Although this may seem counterintuitive, using baking soda to raise pH can ultimately lower alkalinity. Baking soda increases carbonates in the water, which has more of an effect on pH than alkalinity. As pH rises, it causes some of the bicarbonates responsible for alkalinity to convert to carbonates instead. This decreases bicarbonates and therefore alkalinity.
Add baking soda to raise pH above 7.8, closer to 8.0. Test regularly and add baking soda in small amounts to prevent pH from getting too high. The conversion of bicarbonates will gradually lower your alkalinity reading over the course of a day or two.
Change the Water
Completely draining and refilling your swimming pool is the most thorough way to lower high alkalinity. By replacing all of the existing pool water with fresh water that has minimal bicarbonates, you can reset alkalinity essentially to zero. This is the most time consuming option, but necessary if other methods have not reduced alkalinity sufficiently.
Drain the pool either to waste or onto lawn or landscaping that can benefit from the nutrients in the water. Refill the pool completely with fresh water and retest. You’ll also need to rebalance calcium hardness and any other chemical parameters after refilling the pool.
Tips for Lowering Alkalinity Quickly
- Test alkalinity levels every few hours to monitor progress.
- Run the pool pump and filtration system continuously while lowering alkalinity.
- Add chemical treatments or fresh water in increments, retesting after each addition.
- Target an alkalinity decrease of 20-40 ppm at a time.
- Don’t let alkalinity fall below 60 ppm, which can damage the pool.
- Adjust pH after reaching the desired alkalinity level.
The Effect of High Alkalinity
Let’s take a look at some of the negative effects that high alkalinity can have on your pool if not lowered to proper levels:
| Alkalinity Level | Effects |
|---|---|
| Over 180 ppm | pH difficult to adjust, tends to stay high |
| Over 300 ppm | Cloudy water, scale formation |
| Over 400 ppm | Possibility of staining and plaque buildup |
As you can see, allowing alkalinity to remain very high for long periods can lead to numerous issues that will require more extensive treatment down the road. By lowering alkalinity promptly, you can avoid many of these problems and maintain good water balance.
Target Alkalinity Level
Once you’ve lowered your pool’s high alkalinity reading, you’ll want to be sure it’s within the ideal range. For most pools and spas, target an alkalinity reading between:
- 80 – 120 ppm for chlorine pools
- 100 – 120 ppm for saltwater pools
- 80 – 140 ppm for spas
Testing alkalinity weekly will help you monitor and maintain proper levels. Be prepared to make adjustments any time the reading falls outside of the ideal range.
Lowering Alkalinity Without Chemicals
If you want to avoid using alkaline-decreasing chemicals, there are a couple options to reduce alkalinity naturally:
Use a Metal Stain and Scale Control Product
Metals like copper, magnesium, and zinc can help bind with carbonates and slowly reduce alkalinity levels. Using a sequestering agent or metal stain and scale inhibitor containing these metals introduces them to the water.
Over several days, these metals will form complexes with carbonates and cause them to precipitate out of the water. This gradually decreases bicarbonates as well. Make sure the product is formulated for pool use before application.
Add Ion Exchange Resin
An ion exchange resin can also be used to remove both carbonates and bicarbonates from pool water. The resin beads exchange hydrogen ions for carbonate and bicarbonate ions as the water passes through. This lowers total alkalinity without affecting pH or other chemical parameters in the pool.
The resin beads need to be periodically recharged with hydrochloric or muriatic acid as they become saturated. Find pools-grade ion exchange resins to lower alkalinity over time without diluting or draining the water.
Preventing High Alkalinity
To avoid having to lower alkalinity frequently, there are some steps you can take to prevent it from getting too high:
- Use a water testing kit to monitor alkalinity weekly.
- Automate water testing with electronic sensors to catch rising alkalinity early.
- Add regular doses of muriatic acid or alkalinity decreaser for maintenance.
- Watch for excessive scale formation on pool surfaces.
- Replace or clean filters more frequently to remove carbonates.
- Have a pool professional manage your chemicals.
Paying close attention to your alkalinity reading from the start and making preemptive adjustments is much easier than having to deal with extremely high levels after the fact.
FAQs
What causes high alkalinity in pools?
Alkalinity usually rises from bicarbonates dissolved in the fill water or added through pool chemicals. Over time, heat and aeration can cause carbonates to convert to bicarbonates, increasing alkalinity. Not replacing filters as needed also allows carbonates to build up.
How fast does alkalinity increaser work?
Alkalinity increasers raise levels within a few hours typically. Sodium bicarbonate dissolves quickly in water to increase bicarbonates. Test levels every 1-2 hours after addition until the desired alkalinity reading is reached.
Which chemical raises alkalinity the fastest?
Sodium carbonate (soda ash) raises alkalinity the quickest. It fully dissolves and dissociates within an hour to increase carbonates after application. Sodium bicarbonate works only slightly slower to raise alkalinity.
Is it bad to adjust alkalinity daily?
Frequent, small alkalinity adjustments are not harmful, and sometimes necessary to keep levels in balance, especially in very small bodies of water. However, fluctuating alkalinity too severely or too often can make balancing other chemicals difficult.
Should you raise alkalinity before lowering it?
No, it is not necessary to raise alkalinity before lowering it. Adding baking soda or alkalinity increaser first provides no benefit and will only make lowering it more difficult. Alkalinity reducers can be applied directly whenever alkalinity is too high.
Conclusion
Having to deal with high alkalinity levels can be frustrating, but thankfully there are several effective options for lowering it quickly in your swimming pool. Using an alkalinity decreaser product provides the fastest result. Diluting the water or using muriatic acid can also work very quickly when done properly. Adjustments to pH and chlorine can also help lower alkalinity within a day or two.
Bringing alkalinity down to the ideal range promptly will allow you to rebalance related water parameters and avoid common issues like cloudiness, plaster damage, and scale formation. With routine testing and preemptive alkalinity management, maintaining proper levels long-term becomes much easier.