What is Pool Salt?
Pool salt is functionally the same as table salt, except with a coarser grind and larger crystals that work well with chlorine and bromine generators. Most pool supply places sell pool salt in bulk rather than forcing you to get small canisters suitable for the kitchen.
Salt is a popular source of chlorine because it’s affordable and easy to get. It also doesn’t have the same risks as other sources of chlorine or pool cleaners.
However, pool salt is not the same as some popular kitchen varieties. People use Himalayan salt, Epsom salts, Kosher salts, and other salts in their food, but these often have additives or minerals that give them their distinctive flavors and properties that are bad for pools.
The best pool salts are as close to pure sodium chloride as possible. It’s prohibitively expensive to get 100% pure salt because there will always be trace minerals and impurities, but up to 99% pure is both easy and affordable.
Types of Pool Salt: Pros and Cons
There are three common types of pool salt. While you can use other salts in your pool, you shouldn’t; these are the three types that work best and are the least likely to have unintended consequences on your pool.
Mined salt is the best type of salt to use in your pool. This variety ranges from 95% to 99% pure sodium chloride and, as the name suggests, comes from mining it out of the earth. This is easily the most popular type of salt in the United States, which is part of why it’s so affordable to use in pools.
The US produces millions of tons of mined salt annually, usually through deep shaft mining, where companies can extract it in large chunks and break it up to their preferred consistency. Mined salt also works particularly well with chlorine generators because there are few impurities to corrode or damage the systems.
Mechanically Evaporated Salt
Mechanically evaporated salt comes from artificially-generated heat that removes salty water, leaving the crystals behind. Generating heat just to boil water and create salt is rarely cost-effective on its own, so some companies do this as a secondary use for heat created for generating power. If they’re paying to generate the heat anyway, reusing that heat makes it far more affordable to make this salt.
In most cases, mechanical evaporation systems use specific temperatures designed to kill off bacteria, brine shrimp, and anything else that may be in the water before it’s evaporated. Through further processing, it’s easy to remove most of these and leave moderately pure salt crystals behind.
Mechanically evaporated salt usually contains more minerals than mined salt, including calcium, copper, and iron. These are generally bad for pools, so you may need to use a metal sequestrant and monitor the calcium hardness in your pool to keep things under control. This added work is why mechanically evaporated salts aren’t as good as mined salt.
Solar salt is similar to mechanically evaporated salt, except that it uses wind and sunlight to evaporate the water. This is extraordinarily cost-effective because nature does all of the work, and evaporation areas are easily reusable, making solar salt one of the most cost-effective options currently on the market.
However, this process also temporarily increases the presence of brine shrimp and bacteria in the salt. They die when the ratio of salt to the water gets too high, but it also means solar salt has a particularly high level of impurities when compared to other types of pool salt. This is why solar salt is the worst of the three types of pool salts.
Getting The Right Pool Salt For Your Chlorine Generator
Salt is salt, isn’t it? Not exactly. Even if you’re using pure mined salt, the crystals you get aren’t necessarily the right choice for your chlorine generator. Generators may use anything from a fine-grind suitable for use at your table to rough, coarse crystals piled on top of each other.
If you don’t use the right grind for your salt water chlorinator, it won’t work the way it’s supposed to. Getting the right size of salt crystals for your chlorinator is more important than the exact type of pool salt you use, so check your user’s manual and, if necessary, contact companies for more information before you go shopping.
How Should I Add Pool Salt To My Pool And Generator?
Adding pool salt is easy! Follow these simple steps to get the optimal levels of salt in your pool. Trying to convert your pool to salt water? Read my salt water pool conversion guide first.
Step 1: Determine How Much Salt Your Generator Needs
Most salt chlorine generators need between 3000 and 4000 parts per million (ppm) of salt. When you’re adding salt, it’s best to aim for the middle of your generator’s range so it will continue working properly even if the concentration goes up or down a little. Check the owner’s manual for your generator to determine the actual range.
Step 2: Determine How Much Salt Is In Your Pool
Salt test strips are the best way to test how much salt you have in your pool. Brand-new pools usually have 0 ppm, which makes the calculations much easier. Traditional chlorine pools often have around 500 ppm.
Alternatively, you can take a sample of your swimming pool water to your local pool store. Most stores provide free, accurate tests.
Step 3: Calculate How Much Salt You Need
The exact amount of salt you will need varies based on the purity of the salt. That is, you don’t need as much 99% pure mined salt as you would, say, 92% pure salt from another source. Most pool salt products explain how much they will increase the ppm in various standard pool sizes, so use these as a guide.
The larger the pool, the more salt you’ll need. Most stores sell them in 40-pound bags. You can use my pool volume calculator to determine how many gallons of water are in your pool. Use my pool salt calculator to help you determine the right salt levels for your pool volume.
Step 4: Turn Off Your Chlorine Generator
Yes, I said that correctly. Do not run your chlorine generator when adding salt. Wait until all of the salt is dissolved before you turn it back on. Leave your pump on to circulate the water.
Step 5: Add The Salt
Finally, add your salt. For the best results, put it in the shallow area of your pool (or the closest equivalent). Do not add the salt directly into the skimmer area. When adding salt for the first time, it usually takes about 24 hours to dissolve properly. Afterward, test the salt levels again to be sure they’re right, adding more salt as needed.
If you’re not sure how much to put in, start low. It’s much easier to add more salt than it is to drain your swimming pool a bit, refill it, and then add more salt. If you find that you added too much salt – don’t worry! Head over to my guide for what happens if too much salt is in your pool.
Congratulations, you’re done! Questions? Send me a note, and I’ll be happy to help.
Thinking of converting to a salt pool? Read my salt water pool conversion guide first.
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