If you have to winterize your salt water pool at the end of summer, there are a series of things that need to be done to ensure it’s done properly. Depending on your preference and how harsh your winters, you might add chemicals to the water at closing such as chlorine or shock and perhaps an algaecide.
One question people often ask is whether or not they should add more salt to the pool shortly before closing to keep the salt levels at a good level over winter.
When your pool is closed for winter there is no benefit by adding salt to the water. Chlorine is only produced when dissolved salt is pumped through the chlorinator cell with the chlorinator running so adding salt to a pool that isn’t operational serves no purpose and may lead to staining of the pool.
Let’s take a closer look at when to add salt to your pool and when you should avoid doing so.
Should I add salt to my pool in winter?
Don’t add salt to your pool in winter when the pool has been closed and the pump is shut off. Salt will simply sit at the bottom of the pool and slowly dissolve but in a big pile at the bottom. Even if you use granular pool salt which dissolves faster, you only want to add salt during the season when the pool is open with the pump running.
Salt is added to your pool to dissolve and get converted into chlorine to sanitize your pool water. There is no reason to add salt to a pool that has already been closed for the winter as no chlorine is being produced and thus more salt is not needed.
If you happen to live in an area that enables you to keep your pool open during the winter, that’s a different story. If your pool is able to be used in winter, then you want to keep the salt level in range:
2700 parts per million (ppm) to 3400 ppm is the suggested salt level range.
Use your chlorinator’s salt reading feature and disposable test strips to ensure that salt is kept within this range.
If you keep you pool open in the winter but shut off the pump and don’t run it, you still don’t need to add salt. Only add salt when needed (i.e. salt level is low) and when the pool pump is operating.
Should I add salt to the water shortly before closing the pool for winter?
Adding salt shortly before closing the pool for winter should be avoided. Having a high salt level in a pool that is closed and has stationary water that is not moving can lead to stains on the pool walls and floor if the salt level is too high. Remember that salt has a corrosive effect on metal too.
If you’re going to drain water so you can cap the water returns and winterize the pool because you live in an area with freezing cold winters, there is even less point in adding salt shortly before closing the pool. When you drain the water at closing time, you’ll just drain much of the salt with it.
In this instance, you’re just wasting money on salt that will literally be going down the drain along with the water that is removed for winterization.
What happens when temperatures drop in the autumn
When summer comes to an end, you may still be able to use your pool especially if you keep your pool heater running or if you’re ok with cooler water after the best days of summer are behind us.
But later in the autumn when the temperature drops, your pool’s chlorine requirements decrease and at some point your chlorinator will stop producing chlorine. Many chlorinators will no longer produce chlorine when the water temperature drops below 60° F (15° C).
It’s a safety mechanism because when the temperature drops this low, the chlorinator has to work harder to produce chlorine and taxes the system. Plus as mentioned above, your pool’s chlorine requirements are lower than during the hot summer anyways.
So if you keep your pool open late in the season and the chlorinator shuts off due to low water temperature, the salt isn’t getting converted into chlorine anyways so adding more salt will have no effect.
Adding more salt at this point in the season really isn’t necessary unless your salt level is low. Keeping an eye on salt levels during the season helps to ensure you don’t need to add salt later than about halfway through the pool season.
When to add salt to your pool water
The obvious answer is to add salt to your pool when your salt level is low and is outside the desired range which is typically 2700 ppm – 3400 ppm. You have to be careful about adding too much salt because while it’s relatively easy to raise the salt level – you simply add salt to the pool – lowering the salt level generally means draining water and refilling it with fresh water to dilute it.
When you drain water though, you’re also draining out chlorine and every other chemical in the water at that time which can throw water chemistry out of whack. That costs you time and money to get it right again.
In general terms you will find yourself adding salt to your pool:
- In the spring when you open the pool.
- Midway through the pool season or whenever you find that the salt level is low.
Final thoughts
Don’t add salt to your pool shortly before closing it nor during the winter as it serves no purpose. Check salt throughout the season to keep it in the range of 2700 ppm – 3400 ppm unless your chlorinator manufacturer suggests something sightly different. That way you don’t have to even think about adding salt later in the season near winter closing time.
Check out my article on the main reasons why you lose salt in your pool water. It’s not evaporation in case you’re wondering…
If you’d like a bit more information on how to actually physically add salt to your pool, check out my article called How To Add Salt To Your Pool (Instructions).