Shocking your pool isn't necessary, although, it's not a bad idea either. If you get an extremely heavy rain fall, you could shock your pool for good measure. This will help fight off any contaminants that the rain may have brought to your pool.
Use shock treatment on your pool one or two days before the storm. Add chlorine levels significantly during the treatment and let it run for 24 hours to allow the treatment to fill the entire pool. Make sure all furniture or items around your pool are safe to prevent injury to persons or property.
If your pool pump manufacturer has declared your pump is rain safe, you can leave it on in rainfall. Nevertheless, during a thunderstorm, it is highly recommended that you switch off and unplug your pool pump to prevent any costly and irreversible damages to your pool equipment.
Should I run my pump while it's raining? Zagers says yes! We recommend that our customers run their pumps rain or shine UNLESS we have an electrical storm. In that case, lightning could strike an outside circuit, which could damage your pump and other equipment.
When rainwater and 'run off' enter the pool, they can change your water's pH, calcium hardness, total dissolved solids (TDS), alkalinity and other chemical levels as well as bring contaminants (e.g. debris, dirt) into the pool.
One heavy rain is all it takes to throw off your pool's chemistry by unbalancing the pool water's pH and making it slightly more acidic. This additional acidity and nitrogen provide a breeding ground for algae that will turn your pool green.
"Heavy rain dilutes pool chemicals, especially salt and chlorine, which causes the pool to turn green. This means the water is not sanitised or healthy, so it's vital to address this.
Since rain is diluting your pool, you may expect that it will reduce the acidity of your pool water. However, all rain in the US is acidic due to pollution, so rain actually decreases your pool's pH – in other words, the pool water becomes more acidic.
With a rain storm, any number of contaminants can be washing into your pool – acid rain, pollen, insects, tree droppings, dust, sand and even phosphates. Any one or combination of these things in rain can make your pool cloudy.
When is it safe to go into a pool after it's shocked? In general, it's recommended that you wait up to 24 hours to hop into a pool after it's been shocked, depending on the size of the pool, Alan says.
It's pretty tough to over-shock your pool; shocking your pool two days in a row with the proper dosage for your pool volume shouldn't be a problem – and in fact, is sometimes even needed to rid your pool of algae and other contaminants.
Normal, clean rain has a pH value of between 5.0 and 5.5, which is slightly acidic. However, when rain combines with sulfur dioxide or nitrogen oxides—produced from power plants and automobiles—the rain becomes much more acidic. Typical acid rain has a pH value of 4.0.
Swimming pool owners can add disinfecting and stabilizing chemicals as they please when it rains. However, continuous rain will adversely affect the water's chemical balances. This is because rain picks up atmospheric contaminants, such as organic materials and even algae spores, when it falls.
After Shocking Your Pool
It is safe to swim once your chlorine levels are around 5 ppm or after 24 hours. It is always best to test first!
Brown pool water is often caused by metals (iron) becoming oxidized in the pool water. If you shocked your pool water and it turned brown you probably have metals. Oxidized iron usually turns a brown or rusty color in the water.
Although, if you overdo the shock treatment, you risk getting green hair from chlorine due to the excess chlorine oxidizing the copper in the water. You can execute a shock treatment with a few different types of pool shock, just be mindful of how much you're using.
Pools can immediately turn green after shocking when they have metals like copper in the water. These metals oxidise when exposed to high levels of chlorine which makes the pool water turn green. Adding a metal control product such as Zodiac Metal Remover will help to restore the pool water.
A pool filter should be run for a minimum of 6 hours after shocking a swimming pool. This is to allow the filter to clean the water and give the shock enough time to fully mix with the pool water. Running the filter after shocking for 24 hours to 7 days is necessary if the pool has a large amount of algae.
Before you start pouring shock in the pool, the first step is to brush the sides and floor of your pool to loosen all the algae. Doing this breaks the skin and allows the pool shock to more easily kill the algae. Once you've done this, it is important to make sure you have the proper pH level in your water.
Shock Your Pool with Chlorine to Kill Algae
This is the main event in clearing a green pool—killing the algae. Pool shock contains a high level of chlorine that will kill the algae and sanitize the pool. For the best results, use a shock that contains at least 70% available chlorine (calcium hypochlorite).