Rain and Swimming Pool Water Balance
Have you ever wondered how rain affects your pool's water balance? Maybe you've even made a practice of testing you pool water after a rainstorm. Although we typically think of rain water as an unpolluted water source, its chemistry is very different than your swimming pool water. This article will answer the question, what does rain do to my pool water?
Rain and Pool Water Levels
Let's just get the obvious out of the way first. Heavy rain will raise you pool's water level. This make sense but wat are the affects of a rain event raising your pool water? Rain and evaporation are processes that are constantly raising and lowering your pool water level. A heavy rain can raise you water level above your skimmer box opening. This water level change will prevent your skimmer from collecting the floating debris on your pool's surface. In a few hours, this floating debris will end up on your pool's floor where it is more difficult to remove.
Your skimmer is your pool water's first line of defense. It is designed to remove anything floating on the pool's surface. Most debris will be trapped by your skimmer baskets or your pump filter basket. Anything that makes it through this removal system will enter your filter for removal or remain in circulation.
It is important to lower your water level whenever it rises above your skimmer box. In fact, this is probably one of the easiest ways you can keep your swimming pool clean without touching a pool tool. It is recommended to maintain a water level that covers around 50% of your skimmer box opening. Levels below and above 50% will begin to impede your ability to remove surface debris.
If a rainstorm overfills your pool above the skimmer boxes, you will need to lower the water levels. The best way to drain your pool in this situation is by setting your filter to "waste". You can even use this high water level to vacuum your pool floor, killing two birds with one stone.
Rain and Pool pH
Rain water pH will vary depending on where you live. In general rain is slightly to moderately acidic and can range from a pH of 6.2 - 4.3. The ideal pH range for swimming pool water is 7.2 - 7.6. So, heavy rain can lower your pool's pH. It is important to measure your pool's pH following a rain storm. You may need to add a pH up product to raise your water's pH back up to recommended pH levels. But, before you do this you should first balance your pool's alkalinity.
Rain and Pool Alkalinity
Rain will normally have a very low alkalinity, zero in some cases. Heavy rain will have a dilution affect on your water lowering your pool's alkalinity. The heavier and longer the rain, the greater the dilution to your pool water. Test your alkalinity following a rain and balance it first if necessary. Then move on to pH and chlorine.
Rain and Pool Chlorine
You probably know that chlorine is the most common chemical used to sanitize you pool water. Chlorine kills micro-organisms in your swimming pool like bacteria and algae. It is important to maintain healthy chlorine levels to control these microbes and prevent future outbreaks.
Heavy rain will also have a dilution effect on the chlorine in your pool. Once you have balanced your alkalinity and pH, you will probably need to add chlorine.
Green Tint in Pool After Rain
If you notice a green tint in your pool after a rain session, you are probably observing early stage algae growth. Algae can enter your pool a million different ways including during rain. It may be washing off you pool deck or from the trees in your yard. Algal spores can even enter you pool from a wind gust. This algae can reproduce quickly especially if your chlorine has been diluted. Brushing you pool's surfaces is also an important part of algae control. Algae is more susceptible to the sanitizing action of chlorine when in is suspended in water.
If you do see an increasing amount of algae, you will need to balance your water, shock you pool and use an algaecide. You should also run your filter regularly while working to control algae. Your filter will help remove the dead algae from your water.
Can You Swim While It's Raining?
Did you know this is one of the most searched pool related questions on Google? It's true although it seems like common sense. If you have ever swam during a summer rain, you know how peaceful and enjoyable it can be. But what about lightning? Over 300 people are struck by lightning in the United States each year. Swimming during lightning rich conditions is not advised. If you see lightning or hear thunder close by, do not swim in your pool. You may want to consult your local lightning advisory if you are uncertain if conditions are favorable for the production of lightning.
Rain is not bad for your swimming pool but it can unbalance your water or introduce algae which could lead to bigger problems. Just test and re-balance your water after each heavy rain. It's that simple. Good luck and happy swimming!
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