One of the biggest myths about saltwater pools is that they don’t have chlorine.
They do.
On this website I usually distinguish between saltwater pools and regularly chlorinated pools for lack of a better term.
But both types of pool do contain chlorine which is the sanitizing agent that keeps your water free of bacteria and helps the water remain crystal clear.
You can use chlorine tablets in a saltwater pool when required but be careful about using too much concentrated chlorine as it can damage the plates of your salt cell over time. It can also bleach the liner and cause other damage if you’re not careful when adding it.
Below we’ll discuss more about how a saltwater pool needs chlorine manually added from time to time and the best way to go about doing so.
How should I manually add chlorine tablets to my pool?
Chlorine tablets are also commonly referred to as pucks. They are round and are made from compacted chlorine that is highly concentrated. A good quality product will be stabilized meaning that it includes cyanuric acid which we’ll talk about more below.
The reason they are in puck form is for convenience. You typically put one or more as required into your side skimmer with the pump running and over time, they will slowly dissolve and enter the pool.
Back in the day when only liquid and crystal chlorine was available, you had to measure out the chlorine and spend more time storing it, handling and pouring it into the water. With a tablet, you just put it into the side skimmer and it’ll dissolve on its own.
Never toss chlorine tablets directly into the pool as they will sink to the bottom and sit there for hours or longer and can bleach the pool liner.
Chlorine tablets are highly concentrated so read the instructions to be safe.
What other benefits do chlorine tablets offer a saltwater pool owner?
Depending on how much water your pool holds and other factors (how much sun you get, degree of pool usage, etc) you can typically find yourself adding 1 – 4 chlorine tablets per week to your pool. It’s just a matter of putting the tablet(s) in your side skimmer and allowing it to dissolve on its own.
Other than the convenience and ease of use, chlorine tablets offer another benefit that regular chemical chlorine doesn’t have.
While regular chlorine just has chlorine on its own, tablets usually contain cyranuric acid or stabilizer which helps to protect the chlorine from the sun’s rays. Cyanuric acid is an important part of saltwater pool water balancing.
What ingredients are chlorine tablets made from?
The makeup of chlorine tablets is a benefit on its own because they tend to incorporate several ingredients that adds to the convenience. Chlorine tablets are typically made from:
- Trichloro-S-Triazinetrione or simply Trichlor which is a very concentrated form of chlorine.
- Cyanuric acid which is also generically known as stabilizer which helps to protect the chlorine from the damaging rays of the sun. It’s kind of like sunblock for your chlorine.
So if you see stabilized chlorine tablets, that’s what this means. You’re getting a highly concentrated level of chlorine per tablet – 90% is good – plus the cyanuric acid which saltwater pool owners normally have to add anyways.
If you choose cheaper chlorine tablets with no stabilizer, you’ll have to add the cyanuric acid yourself typically in powder form. If you don’t, your chlorine usage will go up as it won’t be protected from the sun.
Why would I manually add chlorine to my saltwater pool?
Common reasons you will manually add chlorine regardless of the format to your saltwater pool include:
- During your pool opening in the spring when chlorine levels are 0.
- After heavy pool usage when chlorine is quickly utilized.
- During particularly sunny days when the strong sun’s rays quickly kills chlorine.
- After a heavy rainfall when the chlorine level drops due to dilution.
- At pool closing in the autumn to keep chlorine levels high and avoid algae growth.
As we’ll see below, while a saltwater chlorine generator is good at maintaining the level of chlorine in the pool, it’s not great at quickly raising it. This is fundamentally why you will manually add chlorine to a saltwater pool from time to time.
Why does a saltwater pool have chlorine?
A saltwater pool is a chlorine pool. While an old style chlorine pool involves manually adding chlorine as the sanitizing agent to kill bacteria, a saltwater pool uses a salt chlorinator generator to convert dissolved salt (NaCl) into liquid chlorine.
So the main difference between a saltwater pool and regular chlorine pool is how the chlorine is supplied. A saltwater pool produces chlorine from dissolved salt. A regular pool uses chemical chlorine manually added on a weekly basis (typically) by the pool owner.
But they are both chlorine pools.
Another main difference: The chlorine produced in a saltwater pool produces no smell and doesn’t annoy your eyes the way regular chlorine does. But it’s still strong enough to kill bacteria and keep your pool water clean for swimming.
How does manually adding chlorine to a saltwater pool help?
While a saltwater chlorinator keeps the chlorine level in your pool at the required level, it can be difficult to quickly raise the chlorine in the water on its own.
When you open a saltwater pool in the spring, you have a chlorine level of 0. It’s not uncommon to dump in a large amount (depending on the size of your pool) of liquid chlorine to get the chlorine level up quickly and to kill off bacteria that has developed over winter.
Going from 0 to 1 ppm – 3 ppm (parts per million) of chlorine in your pool using only the chlorinator is not a reasonable thing to do. It will take far too long and the more stress you place on the salt cell, the quicker its lifespan will be used up and you’ll have to replace it.
If you get a large amount of rain, it can quickly dilute the chlorine so draining some water off and adding chlorine manually may be required.
Also, heavy pool usage and/or very hot sunny days can require you to quickly bump up chlorine levels in a way that a chlorinator simply can’t do fast enough on its own.
How much chlorine does a salt cell produce each day?
Salt cells can produce up to 1.5 lbs of chlorine per day but that would be running it non-stop. The best salt cells from Hayward can typically produce 210 lbs – 725 lbs of chlorine over its entire lifespan. The more you run it, the quicker it will need to be replaced.
If you run your pool pump 8 hours per day, you can only produce 1/3 of the total chlorine that your cell is rated for. But that would assume you have the chlorinator set at 100% which you wouldn’t normally do.
You only need to run the chlorinator at a rate that delivers enough chlorine to keep the reading at 1 ppm – 3 ppm at all times.
What kind of chlorine do you use in a saltwater pool?
The main forms of chlorine you will typically use for your saltwater pool are:
- Chlorine tablets or pucks
- Crystal chlorine
- Liquid chlorine
- Crystal Shock powder (highly concentrated chlorine)
You can use all four types of chlorine in your saltwater pool but it really depends on what your need is and the cost you’re willing to spend.
On a per use basis, the bigger the container the less you’ll typically spend per unit of chlorine. So you’ll probably find crystal chlorine is the cheapest per unit, liquid chlorine is next, chlorine tablets are next and shock is the most expensive.
Shock is usually sold in small packets and is used to shock your pool. So it can come in handy for saltwater pool owners who want to quickly raise the chlorine level by shocking the pool water.
Liquid chlorine is generally good for pool openings and closings only. Otherwise you’re keeping significant amounts of it on hand which is expensive and dangerous since large amounts are required.
Summary
Manual addition of chlorine to your saltwater pool is something that will be required during the pool season. The two chlorine options generally used by saltwater pool owners for regular use are tablets and crystal chlorine.
But the more crystal product you add to the pool at one time the more likely you are to have to mix it into a slurry in a large bucket, allowing it to dissolve, before dumping the slurry into your pool. While you can get away with sprinkling a small amount of crystals across the water with the pump running, larger amounts require you mixing it with water.
Chlorine tablets or pucks are thus very commonly used and help to keep the chlorine level high enough and within range at all times reducing the stress placed on your salt chlorinator.
So the tablets win out in terms of convenience and safety since there is nothing to measure, mix or pour.