Author: Patrick Slusser

As a pool owner, the times of year for opening and closing your pool are entirely up to you.  However the “pool season” as defined by the industry is typically between Memorial Day and Labor Day.  Many pool use this definition as their way of knowing when to open and close their pools.

This is by no means a strict rule but more of a general guideline that people can use.  Some pool owners opt to open their pools earlier in the spring, and close it later in the fall.  They can do this because they either live in an area that stays warm longer or they have a heater that is powerful enough to keep the water warm in cool ambient temperatures.

As a pool owner you just want to make sure that your pool is closed before your area reaches freezing temperatures.  When water freezes it expands and if it expands inside of your swimming pool plumbing components it can cause a lot of damage.  To avoid the potential for this to happen many people wait until after Memorial Day to open their pools, and then close them down again by Labor Day.

I always recommend having a pool professional do the actual opening and closing of your pool, or at the very least the closing part.  It is recommended for a couple of reasons.  First, they tend to know exactly what they are doing.  There can be quite a few steps in the process of closing a pool and if even one small step is missed the result can be dramatic.  The other reason is that many pool companies will guarantee their work.  This means that if anything does happen over the course of the winter, they will be the ones who correct it.  If you were to close your own pool and something happened then the responsibility to fix it would be yours.  Depending on what happens that responsibility can be very costly.

In my opinion the best way to avoid any sort of mishap with your swimming pool over the winter is to make sure it is opened on or after Memorial Day, and closed on or prior to Labor day.  I understand that we generally have warm days outside of that range, but like I stated before this range is more of a general guid line.  Also it is always best to have a swimming pool professional actually do the opening and closing of your pool to ensure that everything will get done the way that it needs to in order to survive the winter.

This is something that almost every pool owner will ask themselves at some point.  Does the pool have a leak or is the water just evaporating?

Just like every body of water, over time the water will begin to evaporate.  Typically you can expect about a quarter inch of water or less to evaporate each day in an uncovered pool.  There are a number of things that contribute to this.  Wind, sunlight, and humidity are the key players in water evaporation.

Wind can blow across the surface of your pool which will cause the water molecules to evaporate much faster.

Direct, intense sunlight will help to dry up water molecules and cause more rapid evaporation.

Humidity in the air plays a big role in evaporation.  The more humid the air is, the less water in your pool will evaporate.  Conversely, during dry spells you can expect more water loss through evaporation.  If you think about the air outside like a sponge then you can expect that if it is dry, then it will be able to pick up more water from your pool, whereas if it is already wet then it will be limited in how much water it can soak up.

So how do you know if you have a leak or if the water is just evaporating?

You can not be certain just by measuring the amount of water loss in you pool per day.  However you can conduct what is know as the bucket test.  To do this it is best to start with a full pool.  Then fill a five gallon bucket 2/3 of the way full and set it on the second step of the pool.  From there you will mark the water level on the inside of the bucket.  Next turn off you pump and mark the water level on the outside of the bucket.  Once that is done, turn the pump on again and let it sit for at least 24 hours.  At that point you can compare the water levels.  If the level on the outside of the bucket has gone down further than on the inside then there is likely to be a leak in your pool.  If the level is the same both inside the bucket and outside then the water loss is likely to be due to evaporation.

Properly maintaining water chemistry is a very important aspect of owning a swimming pool.  The water quality in your pool can not only affect your health but it can also affect the swimming pool itself and the equipment which circulates the water.  That being said you can begin to understand the importance of properly maintaining the water in your pool.

People often assume that by adding more chlorine to the pool they will effectively be keeping the pool water clean.  They also tend to think that with more people in the pool they will need to add more chlorine.  The thing about the water in a swimming pool is that you will never know what it needs without testing it.  This is why test kits were made.  Typically with a heavy bather load in the pool the water quality will decrease.  This is due to the fact that the oils in our skin as well as the sun screen that we use get into the pool and bond with the free chlorine preventing it from effectively killing the bacteria and viruses that may be there.

On the other hand if there is a fairly long period of time in which the pool is not used, will it affect the water quality?  In other words, does inactivity in a pool affect its water quality?

This depends on a couple of things.  Typically the water quality will not change much during time of inactivity.  However, one thing that can change is the volume of water in the pool.  If the volume changes, then the water quality can begin to change.  For instance, if the pool is left open and experiences heavy rainfall throughout the time of inactivity then the volume will increase.  It may not be much, but it may be enough to dilute the amount of chemicals in the pool.  In this case you would need to add more to stay within the appropriate range necessary to maintain a clean, healthy pool.  Conversely, if over the time of inactivity in the pool, the pool is left open and experiences several sunny, windy days then you may find that the water volume in the pool has decreased.  This is due to evaporation caused by the sun and wind.  In this case the amount of chemicals in the pool would seem to increase.  In both cases the amount of chemicals in the pool has remained constant, but because the volume of water changed it will either dilute or concentrate the chemicals in the pool.

The amount of activity your pool receives weather it is more or less will affect the water quality to some degree.  All in all it is really best to test the pool water at least once per week to get a good idea of what it needs in order to maintain a clean healthy pool.

Is it okay to allow rain water to get into your pool, or is it better to cover it?  This is a question that many new pool owners ask themselves the first time it rains after their pool is installed.  After all rain water is supposed to be fairly clean right? So how could it have a negative affect on your pool?

After your pool is installed you will find that there is some initial maintenance that you will have to do.  Basically you fill your pool with water and you then you will have to add chemicals, ie. chlorine, algecide etc. to make it healthy to swim in.  From there you will likely be checking your pool chemicals once a week to maintain that ideal amount.  Obviously this represents a fairly significant investment of time and money.  If you fall behind or just brush it off, and you are not keeping up with it then you may find yourself spending more time and money to get it back to where it needs to be.

Rainwater can change the chemistry of your pool.  Just as it is, it can “dilute” the chemicals in your pool.  Ideally you want to keep your free chlorine level between 2 and 4 ppm. (Parts per Million) So this is based on the amount of water in the pool.  If more water is added to the pool then you will have to add more chlorine.  So if a lot of rain water gets into your pool, the amount of water increases and in turn you will have to add more chlorine.

Another thing that is likely to happen is really only an issue if you have a heater or heat pump installed.  Obviously it costs money to run a heater or heat pump.  That being said, if the set temperature is warmer than the temperature of the rain water (which it will likely be) then the cool rain water will decrease the temperature in the pool and you will have to run the heater or heat pump more often to maintain the desired temperature.
So back to the original question.  Is it okay to allow rain water to get into your pool?  The answer is really yes.  It is okay for rain water to get into your pool.  This will not cause enormous problems for the pool and in fact many pools are open to the rain all of the time.  However, if you have the luxury of covering your pool while it is raining, then I would certainly recommend doing so.  It will decrease the amount of time and money you put into maintaining your pool.