Chlorine to saltwater pool conversion
In this article we are going to dive in and take a look at the chlorine to saltwater pool conversion. But we are also going to take a look at several aspects of the saltwater pool and talk about dealing with corrosion and other aspects to keep in mind when you have a saltwater pool. You see, there are some things with the saltwater pool that are necessary for the pool owner to know. This article is long, but there is no need to read through the article in chronological order, take a look at the index underneath and jump right to the section of your interest.
Chlorine to saltwater pool conversion
To convert your pool to saltwater is not a very complicated process and you certainly do not need to empty your pool and refill it with fresh water. What you need to do is to pour and dissolve salt in the pool water and install a salt cell. A salt cell may also be called a salt chlorinator or a salt generator. All salt cells should have a flow meter. Some salt chlorinators have the flow meter incorporated into the salt cell, so that saves us one step.
The flow meter is an important security feature and makes sure that there is water flow to the cell before it starts the electrolysis. The installing of the salt chlorinator is something someone a tiny bit handy can do themselves. The most complicated part of it is cutting some pvc tubes and connecting the chlorinator. Also, most salt chlorinators come with a very detailed instruction.
So here is how you should proceed with your chlorine to saltwater pool conversion:
Install the salt chlorinator
Before proceeding, make sure to turn of the power at the main breaker.
The flow meter may be integrated in the salt chlorinater or it may be an independent unit. If it is independent it must be installed in front of the salt chlorinator itself, usually on a horizontal piece of the pipe. This allows it to control that there is water flow to the cell before connecting. This is an important safety precaution. The salt chlorinator itself must be installed last on the line of equipment. After the pump, filter, etc, just before the pool return.
If your pool has a heater you should also install a one way chlorine resistant valve between the heater and the salt cell. This is to prevent chlorine from traveling back to the heater as that would destroy it rather quickly.
Your salt chlorinator will come with a proper set of instructions that will tell you how much space the unit will need.
Calculate how much salt you need
You need to calculate how much salt to put in the pool. For instance if your pool is of 10,000 gallons (38 000 liters) of water you would need between 267 lbs and 284 lbs (121 – 128 kg) of salt. You can buy them in 40 lb bags, so in this example you would buy 7 bags of 40 lb and a couple of smaller bags to make sure you have enough. The salinity your salt chlorinator requires to function optimally will be indicated in the installation guide. It will usually be given in ppm.
This calculator on poolcalculator.com will help you determine the necessary amount of salt for your pool:
When purchasing the salt, be sure to use at least 99.8% pure and NON-iodized salt. If you do not know how much water your pool hold you can use this volume calculator to find out.
TIP FOR ADDING SALT
If you think you need 7 bags 40 lb of salt, put in 6 or 6 1/2.
- It is a lot easier to add another bag if needed, than it is to remove it if there is too much salt in the water
Add the salt
Make sure your salt chlorinator is turned off. Pour the amount of salt needed in the shallow end of your pool. To help dissolve the salt in the water you can brush it back and forth on the pool bottom with a pool brush.
Then let it sit for a couple of hours. Next you run the pool pump, without running the salt cell, for 4 hours. Now let the pool sit for 24 hours.
Check that the salt level is at the indicated level (as indicated by the salt cell manufacturer, usually around 3400 ppm) before you start the system with the salt chlorinator. Add more salt if needed, make sure it is properly dissolved (run the pump, let the pool sit for a couple of hours) and then measure again.
Your pH is probably OK at this point, but check it anyway. You can use sticks like the ones here below. And finally you are happy with the salt level and pH you can start your salt chlorinator.
Advantages of the chlorine to saltwater pool conversion
- The perhaps most obvious advantage is that you will no longer have to haul home gallons and gallons of chlorine and pour it into your pool.
- You will no longer have to deal with the chloramines, which is the by-product of chlorine, as the saltwater cell will burn those off. That means that you will not suffer the stinging eyes and the itching skin, or the unpleasant chlorine smell.
- Saltwater pool has less chlorine than a traditional pool
- The electrolysis that occurs in the saltwater cell will soften the water, so it feels very soft and comfortable to swim in.
- Some argue that a saltwater pool is economical in maintenance. That depends however of a well kept chemical and pH balance, because that will make the salt cell last longer.
- A saltwater pool however requires less maintenance work overall.
Disadvantages of the chlorine to saltwater pool conversion
- The initial investment in equipment is higher than in a conventional chlorine pool.
Are saltwater pools a more ecological solution?
No, it is not. In fact, to some extent you may be able to backwash the pool water of a regular chlorinated pool on to the ground and let the waste water find its way into the public sewer system.
Not so with the water from a saltwater pool. Removing salt from water is a very laborious and expensive process, so it should not be sent to the local water plant. And if it gets there you might get fined.
Also, the salt, the free chlorine and the pH of this water is dangerous to fish and aquatic life and also the the plant and animals on land so it should not be drained into the ground either.
You may want to consider this before going forward with your chlorine to saltwater pool conversion: Wastewater from saltwater pools is being regulated by federal requirements. Section 301 of The Clean Water Act prohibits a direct discharge of pollutants into the waters of the United States without a permit from the U.S. Environmental Protection Agency (EPA). You will also find that many areas have put bylaws in place to ban salt water swimming pools to drain into the public sewer system. This means that you may have to get it trucked away. This becomes even more of an issue if you have filter like a DE filter that needs regular backwashing.
Therefore, if you go for a saltwater system, you should probably go for a filter system that does not require backwashing. Like a cartridge filter:
Understand the process of a saltwater pool
So while in a freshwater pool you have to keep filling up with chlorine because it will
a) be broken down by the UV light from the sun and
b) turned to chloramines by the ammonia from our body.
In the saltwater pool the chlorine is being produced by the salt cell, also called salt generator or salt chlorinator. Same thing, different names.
The whole process can be described like this:
The pool water contains about 1 teaspoon of salt per gallon (3.8L) of water. This is actually plain table salt and it’s chemical formula is NaCI. The Na stands for sodium and CI stands for Chloride. When the salt is dissolved in the water the bond between the Na (sodium) and the CI (chloride) is loosened.
The saltwater solution is then pumped through the salt chlorinator cell, where a small electric charge (electrolysis) will induce a chemical reaction to create sodium hypochlorite (NaClO) and hypochlorous acid (HClO), which is chlorine. The very same one that is used in freshwater chlorinated pools.
In a regular freshwater pool we would pour in chlorine. When we swim in it, the ammonia from our body (sweat and urine etc) reacts with the chlorine and creates free chlorine and combined chlorine. The free chlorine is what is available for sanitizing the water and is the useful part of it. The combined chlorine is the “used chlorine” and what we call chloramines. This is the one that creates the characteristic chlorine smell, it is also what irritates our skin and stings in our eyes.
The benefit with the saltwater system is that the electrolysis will burn off the chloramines, so we avoid the smell and the irritation on eyes and skin. The concentration of chlorine in a saltwater pool is also much lower than in a freshwater pool.
Maintenance of your saltwater pool explained
The water in a saltwater pool is less salty than a human tear and you can barely taste the salt in the water. Even so, salt is corrosive and a too high salt level could destroy your equipment. The salt level should be maintained stable between 3200 and 4000 parts per million (ppm) and should not never exceed 5500 ppm. The salt level in your pool may also drop due to rain or backwashing. If it drops too low, you will have to top it up again or the sanitizing system of your pool will not work properly and you will get a problem with algae etc. Just as you would in a freshwater pool.
For the chlorine to work most effectively the pH of the pool water should be in the range of 7.2 to 7.6, with the optimal pH at 7.4. A study done by the National Pool Industry Research Center concluded that the chlorine is 65% effective on a pH of 7.2 which is slightly too low and 32% effective at only 7.8 which is slightly too high. So that tells us that it is better to maintain the pH on the lower end of the scale
The salt chlorinator cell is what will cause the pH to rise, and it will rise quickly, so the best is actually to check the pH a couple of times a week. To adjust the PH you should pour liquid hydrochloric acid (muriatic acid) or you could use dry acid (sodium bisulphate) to lower a high pH. If you need to rise the pH you could use calcium carbonate (soda ash). The correct way of adding this components to the pool water to correct the pH is to add the component, then let the pool run for a couple of hours and then measure again. Even if saltwater pool is rather low maintenance it can be quite tedious to remember to measure the pH and correct the continuously. Some salt chlorinators has a reader very conveniently incorporated. But you can even find salt cells with chemical automation. These will not only measure the chemical balance, it will also correct it if needed. They use a CO2 system that buffers CO2 (Carbon dioxide) into your water a couple of times a week and through that lower the pH. These CO2 systems lowers the pH without affecting the alkalinity as the muriatic acid does.
- The salt chlorinator and chemical automation pool control system that is a convenient one box solution for pools
- It has 8 programmable soft keys and also equipped with a salt chlorination cell for pools up to 40,000 gallons
- Features variable speed pump control, super chlorinate function displays time, day, pool and spa temperature and ambient air
- Also controls on-off-timed of pool lights, light shows with Color Logic, Spa jets, backyard lighting, Water features, misters, fire pits and more
Issues with the saltwater pool system
Calcium build up and how to deal with it
In the salt cell you will eventually get a build up of calcium. This is due to both the salt in the water and the calcium hardness of the water used. The heat created by the electrolysis and the high pH in the salt cell will cause the calcium scale to attach to the cell and the build up will cause the cell to lose the electrolysis and eventually fail altogether if not cleaned. That in turn will result in a pool with low or no chlorine and its resulting algae and health issues.
Maintaining the pH on the lower end of the scale will help preventing build up, and also the less you have to run the salt chlorinator the less build up you will get. Hence the usage of a stabilizer like cyanuric acid to slow down the chlorine loss will also prolong the life of your salt chlorinator.
So how often should you clean? Well, that depend on factors like how big your chlorinator is in comparison with the pool. You will see many recommend to buy a salt cell for a pool twice the size of your pool and we are inclined to agree. Yes, the purchase will be more expensive, but you do not have to run the salt chlorinator that long every time as it will be quicker and more effective. Another determinant factor is the hardness of the water. And of course it also depends on the pH of your pool. You can in fact find self-cleaning salt cells. What these does is to reverse the polarity to repel the build up. However, buildup will eventually occur anyway, though to a minor degree. The best way to know when to clean is actually to do a visual inspection of the cell. But also be aware of other signs like that the chlorine level in your pool is dropping as that will indicate that the cell is not working effectively.
In this video Dave, the pool guy explains how to clean a salt cell
The cleaning of the chlorinator is usually done with muratic acid deluted to between 1 to 4 or 1 to 6 proportion. Where the muratic acid will soften the calcium so that it can be removed with high pressure water. One thing to keep in mind though, is that muratic acid is high in copper and will kill any bacteria, also the useful bacteria en your waste water treatment plant, so check with your local authorities as they should have a provision for disposing of it.
Scale or calcium on the pool walls
If the salt cell is not maintained and the pH in the pool is not properly managed that will create conditions that are very favorable for calcium deposits to form, not only in the salt cell but also in the pool itself.
This is often called “scaling state” and means that you can get deposits on the walls and floor, and that can become a very cumbersome and expensive issue to resolve.
If you notice that scaling has started to build up in your pool you can maintain it using a scaling solution like this one.
Prevent corrosion with a zinc anode
Salt and metals are known to be a notoriously bad combination. In saltwater something called galvanic corrosion may occur. This refers to the fact that if dissimilar metals are immersed in salt water they will produce a tiny electrical voltage and corrosion will attack the weakest metal.
A zinc anode is a soft peace of metal often put in the skimmer and is acts as a sacrificial anode. It allows the potential electricity in your pool to attract to the zinc anode instead of any other metal or to your pool system and break it down. It is a very simple and inexpensive solution.
One of these in each skimmer basket will save you a lot of money and trouble.
If you decide to go for a chlorine to saltwater pool conversion or just plain start with a saltwater pool, this is what you should keep in mind:
- The initial cost is higher, but it may be less expensive in the long run
- The water in a saltwater pool is less irritating on the skin and eyes and creates less problems for asthmatics
- Yes, you must keep a close eye at the pools pH value, but there is generally less maintance work to do
- A saltwater pool is not a chemical free pool, nor is it chlorine free
- A saltwater pool is not a more environment friendly solution.
- Ideal values are:
- salinity is between 3400 – 4000 ppm (that mean about 0.34% – 0.4% salt), your chlorinator will indicate the ideal amount for it.
- PH level between 7.2 – 7.6 where the ideal is 7.4
- Calcium hardness of 180-200 ppm
Should you prefer to go completely chem-free do read our article on Natural Swimming Pools that uses no chemicals at all.