Rainfall dilutes pool chemistry levels and lowers the readings for pH, alkalinity, hardness, stabilizer, and chlorine. Rainfall does not contain chlorine. As well, rainfall brings with it small amounts of contaminants that are washed into the pool.
Swimming in the rain isn't worth the risk of getting hurt. Stay away from the pool during rain showers, and if you must enter the area for whatever reason, bring someone along so you aren't alone around the water.
If you get more than five inches of rain in an hour, or if your pool wasn't properly designed with sufficient overflows, then your pool may overflow, which can put you at risk of water getting inside of your home and causing serious damage. As your pool fills with water, it may overflow into your yard.
Heavy rains will deplete many of the chemistry levels in your pool. Generally your alkalinity will drop significantly. It is a good idea to have Alkalinity, Muriatic Acid, Chlorine (or Salt), and Shock on hand to be able to test your water and treat your pool immediately after the rain stops.
It is entirely safe to run your pool pump when it's raining – most of the time. Running your pool pump during rain should not affect the pumps' ability to do the job it was designed to do.
What happens if my pool overflows? Most of the time, when your pool overflows, it's a big headache, but nothing that can't be remedied. You'll just need to wait for your yard to absorb the excess, drain off some pool water, and balance your pool chemicals. That's the best case scenario.
If your poor overflows, you will need to shock the pool with chlorine, then re-adjust your pH and chemical levels over the next week by continually re-checking the pool's pH with a pool test kit. If the pool was contaminated with debris or dirty water, you will have to clean or replace your filter.
Leave Your Pool Open
When preparing your pool for a storm, leave it uncovered. Installing any kind of cover across the pool will not do much to protect against dust and contaminants because storms often bring strong winds and heavy rain that can cause the cover to lift off your pool.
Remember, rain is acidic. Hence, pool overflowing from rain causes the Alkalinity and pH levels to lower. Very low pH causes pool water to turn very clear and acidic, which destroys your pool surface and equipment.
Why Your Pool Turns Green and Cloudy
While the rain itself doesn't generally harm your pool, it can dilute the carefully balanced chemistry in the water. This can alter your pH levels and dilute the chlorine or other sanitizers, allowing algae or other contaminants to gain a foothold.
You should keep the pump dry and out of the rain. Rain that is allowed to fall on the pump can get into the motor and cause a short circuit, burning out the motor in the process. Cover the pump and never allow water to fall on it from above.
After it rains, you should remove standing water as soon as possible. To do this, you'll want to use a siphon or a water pump. An automatic pool cover pump is one of the most useful pool supplies in New Haven County, CT because it can remove standing water from your cover without you needing to do the work.
Green pool: Leaves, dirt and algae spores delivered into the pool water decompose, causing phosphates to be deposited into the water. Combined with sunlight, these conditions are perfect for algae and other contaminants to grow and affect the health of the pool, turning it green overnight.
Effect on Pool Water pH
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.
Should the green be due to pollen, there may be little to do in the way of minimizing the discoloration short of erecting a building around the pool. Fortunately, assuming there are no allergies to the pollen, it is safe to swim in a pool with that as the cause for green water.
Close the pool for winter – but don't drain it.
In winter, the water in your pool is still your friend. Especially when properly winterized, it helps to protect the pool liner, keep it clean and prevent unnecessary damage from debris, harsh weather and other factors.
An uncovered pool will lose water in the winter to evaporation in the same way it does during the summer. But the water loss is only about a quarter-inch on average during a 24-hour period when the pool is not in use. An uncovered or covered pool can have problems in the plumbing lines or pump.
This will vary depending upon several factors including: weather, if the pool is covered or not, bather load, and if it is heated or not. With pools that are covered, a good rule of thumb is that they should not have to be refilled more often than once every 2 weeks.