Managing Your Pool After Heavy Rainfall
Stormy weather, particularly heavy rain accompanied by strong winds, is a familiar occurrence in the Midwest and many other regions across the globe. One moment, the skies may be clear and sunny, and the next, dark clouds roll in, unleashing torrential downpours. Many pool owners have reported challenges in maintaining their pool’s chlorine and pH levels following significant rainfall. While rain can indeed impact your pool’s chemical balance, it’s important not to panic with every storm forecast. Below, I will share several strategies I employ—and sometimes choose not to implement—after a rain shower passes.
After a heavy rain, the chlorine levels in your pool will likely become diluted. Depending on the volume of rainfall, you may or may not need to take action. If you experience significant rainfall, it’s advisable to test your chlorine and pH levels and add the necessary products to restore them to normal. Shocking your pool post-rain is an effective method to counteract the dilution caused by the storm.
Test Your Chlorine Levels
Following a strong rainstorm, it’s crucial to assess the chlorine levels in your pool. The intensity and volume of rain can significantly influence the chlorine concentration in your water. In severe cases, a heavy downpour can completely deplete your chlorine levels, leaving your water unprotected from bacteria and algae.
- Utilize your preferred chlorine test kit to determine the current chlorine parts per million (ppm) in your pool’s water.
- If your test indicates a reading of 3 ppm or higher, you likely didn’t receive enough rain to cause major issues, and no adjustments are needed.
- Readings of 1 to 2 ppm suggest a slight dilution; it may be wise to temporarily increase your chlorine dosage and/or administer a small amount of shock to reach the optimal range of 3 to 5 ppm.
- If an excessive amount of rain has fallen, you may find that your chlorine levels have dropped to zero:
- In this scenario, shock your pool with full strength to restore chlorine levels above 3 ppm, then continue with your regular maintenance routine to keep your pool clear and clean.
Test Your pH Balance
Rainfall can also adversely affect your pool’s pH balance due to the naturally acidic properties of rainwater. Consequently, your pH levels are likely to drop following significant rainfall.
| pH Level | Examples |
|---|---|
| 4.0 | Acid Rain Water |
| 4.5 | Acid Lake Rain |
| 5.6 | Clean Rain Water |
| 7 | Pure Water |
| 8 | Sea Water |
| 11 | Ammonia |
The greater the acidity of the rain, the more your pH levels will decline. It’s essential to use a test strip or kit to gauge your water’s pH.
- Check your water’s pH balance a few inches below the surface using your preferred testing kit.
- The ideal pH range is between 7.2 and 7.6. Levels slightly outside this range are usually acceptable, but you should monitor them closely.
- If your pH drops below 7.2, add Borax to bring it back to the recommended levels.
- If your pH is too high, Muriatic Acid can help lower the levels effectively.
If you’re uncertain about how much Borax or Muriatic Acid to add, consider using a Pool Calculator. This free tool can help you determine the appropriate chemical quantities based on your pool’s water volume to achieve your desired pH range.
Three Reasons Not to Shock Your Pool Before a Storm
I’ve encountered individuals who preemptively add extra chlorine, shock their pool, and even adjust pH levels when severe weather is predicted. The rationale is that by doing so, the dilution from the impending rain will be less impactful on their pool’s chemical balance. However, I do not recommend this approach for several reasons:
- Uncertainty of Rainfall: While meteorologists are skilled in forecasting, they cannot guarantee the exact amount of rain that will fall. Storms can shift paths, intensify, weaken, or even dissipate unexpectedly.
- Irreversible Chemical Changes: If the storm does not deliver the anticipated rain, the chemicals added to your pool cannot be removed. This may lead to elevated chlorine levels and pH balance that could pose risks for swimmers.
- Cost Concerns: Pool chemicals are not inexpensive. Even budget-conscious pool owners prefer to avoid unnecessary expenditures. By waiting until after the storm, you can test your water and add only the necessary chemicals, saving money and allowing for immediate swimming.
Skim Pool Surface and Vacuum
If your area experienced heavy winds, hail, or excessive rain, it’s likely that debris such as leaves and branches have found their way into your pool. Intense rain can dislodge foliage from trees, while strong winds can scatter debris across your yard, leading to unwanted material in your pool.
Skimming the surface of your pool after a storm helps minimize the debris that may accumulate in your skimmer. Additionally, some leaves may settle to the pool’s bottom, requiring vacuuming to restore your pool’s cleanliness.
Scrub Side Walls with a Brush
If your pool has undergone a significant rainfall and you couldn’t promptly adjust the chlorine levels, there’s a chance algae may develop. In such cases, shocking your pool and applying an algaecide treatment will eliminate harmful bacteria, including algae. After about 24 hours, when the algae have died and are no longer visible, scrub the walls and floor of the pool, then vacuum up the debris once it settles.
If your water doesn’t return to its previous clarity, consider adding a stabilizer to help clear the pool once the algae has been addressed.
Drain Water Levels if Necessary
When it comes to draining water, utilize a designated drain plug equipped in your pool, a submersible water pump, or for sand filters, use the waste setting to drain excess water. The backwash feature on sand filters should only be activated when backwashing is necessary; do not leave it on for extended periods to drain water.
Above Ground Pools
For above-ground pools that are overflowing, it’s crucial to drain them to restore the water level to the recommended range. If the water exceeds the top of the skimmer, it may be too high. Overfilled pools risk allowing water to seep between the pool wall and liner, potentially washing away sand or dirt from beneath. This is a common issue for above-ground pool owners, but there’s no need for concern; simply return the water levels to normal, and any excess water will dry out.
In-Ground Pools
Some in-ground pools feature an automatic overflow that drains excess water, preventing overfilling. These pools generally do not require additional draining after heavy rainfall. However, other in-ground pools may need to be drained slightly to maintain an appropriate height for optimal pump performance. Typically, in-ground pools remain unaffected by heavy rains, as they are situated below ground level, making draining less critical.
Small Calm Rain Showers
Occasionally, during the spring or summer months, we experience brief rain showers lasting 10 to 15 minutes, or gentle rain that may go unnoticed except for the wet sidewalks and grass. Such minimal rainfall, which registers little to no measurement on your rain gauge, typically has a negligible effect on your pool’s water chemistry and should not necessitate testing or adjustments in your regular maintenance routine.
In fact, as long as there is no threat of lightning or thunder, these light showers can provide delightful swimming conditions. Enjoying the warm waters while light raindrops fall can be a relaxing experience. Only substantial rainfall over an extended period will significantly impact your pool’s chemical balance, necessitating adjustments for chlorine or pH levels.