What Does your Pool Need after it Rains?

2017-04-10T18:41:48+00:00 March 7th, 2017|Info & Tips, News|

 What does your Pool need after it rains?

What does your pool need after it rains? Rain can sometimes ruin your pool water’s careful balance- and if the rain is acidic, it can greatly affect the pH levels. Also, after a heavy rain, there will be extra water in your pool that can dilute the water’s chemistry.

With any heavy rain fall, it is important to check the pH, alkalinity and sanitizer levels. (Using at home test strips will help you with this)

Note: If you get light showers, don’t worry too much about the pool chemistry. A light rain will have very little effect, if any, on your pool water. Feel free to check anyway, if only to make sure everything is balanced.

So what does your pool need after it rains? Below are 4 simple steps to take after a rainfall:

1.Clean Your Pool

Clean clean clean!
Whether you clean it yourself, or have a professional come by, this is an important step.

If the rain comes with any sort of wind, dirt, leaves and assorted debris can be blown into your pool. With dirty pool water, it can be difficult to get an accurate pH reading on your test kit or strips.

We recommend that you start the cleaning process by simply skimming your pool, and then moving on to vacuum the bottom.

You can use an automatic pool cleaner or a manual vacuum, whichever you prefer.  Try to get the water as clean of debris as possible.

Once your pool is cleaned of dirt and debris, you can properly test the water chemistry.
For large leaves and debris, try the Jandy LeafMaster.
Jandy Leaf Master and Fine Mesh Bag


2. Check Your Water Level

If there is excess water in your pool after it rains, there are various methods to drain the excess.

-You can drain some of the water by using your filter’s waste setting. Let the pool drain until it is back at the normal level.

-Some pools have a hose spigot plumbed after the pump, or on the filter valve, which you can connect to a garden hose to lower water level.

-You can use a submersible pump, aka a pool cover pump, to keep the pool from overflowing.

-In addition, there is the siphon method, and a pool vacuum hose works best.
Prepare the hose in the pool, to fill it with water, and attach a vacuum head or use a heavy item to hold the hose on the first or second step, the pool ladder, or swim out.

Cap the other end of the hose with your palm and quickly pull the hose away from the pool and a few feet below the level of the pool water. Uncap the hose at ground level and let it flow. Be careful to keep an eye on it!

3. Check pH and Alkalinity Levels

Any sort of rain, especially acid rain, will cause your pH to drop. The alkalinity in your water will help to balance it out.

Extra water and contaminants can also lower the pH, but the alkalinity will take the big hit. If your alkalinity levels see a more drastic change than your pH levels, your alkalinity is working!

Be sure to keep your pH at 7.2, as this helps the sanitizer work and prevents scaling.

Re-adjust your alkalinity by adding Sodium Bicarbonate – Alkalinity Up..


4. Check Sanitizer Levels

As noted, rain can introduce contaminants into your water, and chlorine or sanitizer levels may be compromised.  If you currently have a good sanitizer level, it will start fighting off the contaminants, which will lower your levels of available sanitizer.

Your calcium or CYA (cynauric acid) levels are not greatly affected by the rain except for some dilution, however it is always good to re-test and add as necessary.

When you have a clear picture of your pH, alkalinity and sanitizer levels, go ahead and balance them back to normal.

Your pool should be good to go!

The Big Question: Do I need to Shock My Pool?

Shock can be beneficial- it assists in fighting off any impurities that may be lurking in your pool.

If your available sanitizer levels are low, you MUST shock your pool or risk cloudy or even algae-ridden water.

If you levels are between 1-3 ppm, then you may want to use chlorine free, O2 Shock.

However, if your chemistry is balanced and the water level is back to normal, shocking your pool is not necessary. Please note- it won’t hurt your pool if you decide to do so just to be cautious.


Clean your filters!  Lots of leaves, sediment and debris will be trapped. The particles don’t disappear with shocking, but rather get trapped in your filters.  Always clean your filters a minimum of 2x a year (we suggest April and October).

There may be additional run-off from your pool deck which can bring contaminants from your lawn or the deck itself. If you follow this short list after a rainfall, your pool should not have any issues (including cloudy water or algae).

Add algaecide before a storm if you have time, to help with the contaminants that may enter your pool.

If you do shock your pool, do so after the chemicals are balanced and the water levels are normal, in the evening after the rain has ended.

Finally, avoid swimming during a thunderstorm – there could be lightning! No one needs to be in a large body of water during that sort of weather.

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