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Above Ground Pool Chemicals (Defined)

When it comes to maintaining a swimming pool, there are so many different pool chemicals to choose from. And there’s big money in it, so the sales and marketing associated with them are really good.

Making sense of pool chemicals for above ground pools

Swimming pool chemistry can be very confusing. When I started a maintenance company in the late eighties, it took me a solid couple of years to get it down and really understand it.


In the real world, there are a few ways to chemically maintain a swimming pool. And the more options we have, the more confusing things can be. As an experienced pool service guy, I can tell you only a few pool chemicals are really needed.

After doing year-round weekly service to a hundred different pools, it doesn’t take long to realize that less is usually more in terms of pool chemistry. Each pool is different though, and since a pool owner isn’t working on pools all day, learning what works for him/her with just their pool is the ideal goal.


This is the first lesson I learned when I started my pool service. There are some basics to chemistry that teach you how unnecessary most specialty pool chemicals really are.

But there are thousands of pool owners out there who maintain their pools very well using stuff that I would never recommend. To this, I say “You can’t argue with success”. If what you do works, then by all means, keep doing that regardless of what I or anyone else may say or do.


My intention here is to explain these chemicals as a pool dude and not Bill Nye the science guy. If beakers and subatomic particles excite you, then you’ll have to google geek-out elsewhere.


Shocking a swimming pool is maybe the most common and most essential task in pool chemistry. But what does shock really mean?

“To shock a swimming pool means that you are adding a whole lot of a sanitizer (Chlorine) in a very short period of time”

When you think of shocking a pool, imagine a nuclear bomb going off in the pool. The bomb sends a shockwave at a very quick speed across the entire environment (the pool) and kills a lot of things instantly. Both quantity of the product and the speed that it is introduced into the water is crucial.

So the term “shock” is a process and not a specific chemical. But shocking does require a lot of a sanitizer like chlorine. Chlorine is by far the most common sanitizer used to shock a pool, but you will see some products called “non-chlorine shock”.

Chlorine (liquid)

This is by far the most common chemical used in swimming pools. There are three main reasons why chlorine is so popular – it’s inexpensive, it’s available everywhere, and it works very well.

Chlorine is an excellent sanitizer(killer) and oxidizer(dissipater) of things that you don’t want living in the pool water. Some pool chemicals are good for killing and others are good for getting rid of dead stuff. Chlorine is great at doing both.

Killing tiny living things and then dissipating them out of the water and into “nothingness” is a huge part of the battle of having a clear and safe swimming pool. If you can learn how to use chlorine properly, maintaining a swimming pool will be very easy.

Not all liquid chlorine is equal. Liquid chlorine can have a range of 5 – 15 percent of chlorine in it. Most chlorine you buy from a pool store (in those reusable yellow 2.5-gallon jugs) will be something close to ten percent chlorine. Household bleach (like Clorox) will be five percent.

Knowitall tip: Liquid chlorine has a shelf life of about one month. This means it will lose its potency from where it started (15%-10%) and end up at just 5%. For this reason, I recommend buying your liquid chlorine from a busy pool store instead of off the shelf at Wal-mart.

Muriatic acid

Also called “hydrochloric” acid, this product is the most common one used to lower the pH in the pool. With my pool service business, this was what we used.

WHAT TO KNOW – Muriatic acid will burn your skin fairly quickly. The good news is that it will neutralize immediately when you pour water on it. Also, you’ll want to avoid breathing in the fumes as they are offensive to your lungs, nose, and eyes.

Muriatic acid has a fairly long shelf-life. Store it with a tight lid in a cool area away from long-term direct sunlight.

NON-RELATED POOL TIP: Pouring just a splash of muriatic acid in your toilet and then gently scrubbing the porcelain will completely clean any kind of build-up at the waterline.

Soda ash/Sodium carbonate

This relatively harmless white powder is used to increase the PH of the pool’s water. It has a nice long shelf life and stores easily. Just keep it from getting wet.

Sodium bicarbonate

Called “bi-carb” by pool guys, this is used to raise this thing called total alkalinity. Total alkalinity or TA has a relationship with PH and helps keep it from fluctuating a lot. You shouldn’t have to adjust the TA very often.

Sodium bi-carb stores easily and has a long shelf life. Oh, and it’s not toxic.

FUN FACT: This product is the same as the baking soda you buy for your kitchen.

Sodium bromide (Yellow Treat/Yellow Out)

This chemical is used to get rid of yellow algae. It needs chlorine present to work, so following the usage directions is important.

For most pools, this chemical will be necessary. Yellow or mustard (as it’s called sometimes) algae wasn’t too common when I started servicing pools in the eighties, but it is now. There are a couple of other methods for getting rid of yellow algae, but using sodium bromide is the best. Read more here about mustard algae

Chlorine tablets

For most pools, the use of chlorine tablets is essential in keeping the pool clear. These will come in either three-inch round pucks that weigh about a half-pound each, or they come in smaller one-inch pills. Regardless, with chlorine tabs, they are the same so size doesn’t matter.

All chlorine tablets aren’t the same though. Some will be made with more chlorine than others. This is why you’ll see some that are much cheaper than others. As a pool guy, I’m looking for tabs with the most active ingredient (Trichloro-S-Triazinetrione) in them. So. I look for one with 99% Trichloro-S-Triazinetrione.

Some chlorine tabs will be considerably cheaper than others. You may think that one retailer is just ripping you off, but if you look closer at the cheap ones, you’ll notice they only have something like 77% chlorine.

Note: Chlorine tabs made with less percentage chlorine will be less effective.

Also, some tablets will be sold as more stabilizing than others. All chlorine tablets that I know of have stabilizer(cyanuric acid) in them. Typically, this is not something to think about when buying tabs. Usually, cyanuric acid doesn’t have to be adjusted in pools very often. If it does, you would use a separate product to adjust it, not more or fewer tablets with more or less stabilizer.

Cyanuric acid (stabilizer)

This is called a stabilizer because this chemical will prevent the direct sun from robbing chlorine from the pool. That’s it. It really doesn’t do much else. So, as long as your chlorine levels don’t go down too quickly, don’t worry about cyanuric levels.

Note: Too low levels of cyanuric acid won’t do much, but pool water having too much stabilizer can add to some issues. As a pool guy, I very rarely tested for or added cyanuric acid as chlorine tablets(that have CA in it) usually take care of that.

Dry acid (Sodium Bisulfate)

Most pool service guys will prefer muriatic acid when lowering the PH in pools. Most of the time, I will only see dry acid as part of a pool’s start-up kit or used by some homeowners.

Dry acid is preferred to be used in start-up chemical kits because it ships and stores much easier. It’s can also be preferred by pool owners because it’s much easier to work with than muriatic acid.

Tip for above ground pools As a general rule, I like using chemicals in liquid form when dealing with above ground pools because they are less likely to damage the vinyl liner.

Metal out

This is more of a general term than a specific chemical. A product called “metal out” or something like that is usually something to put one of the three metals in water that can cause an issue to be able to be filtered out.

You may see the term “sequestering agent” in the description. This means that the product will put the metal in a state and/or make it stick together to be big enough for the filter to capture it.

For above-ground pools, a product to get metal out of the pool is useful when using well water to fill it or if something made of metal has gotten in the water somehow and is causing color or staining issues.


This is another general term for something that kills stuff in the water. Most will have some form of copper in their ingredients. Certain things don’t like to live with or will die from the presence of copper.

Algaecides can also have this thing called quaternary ammonium or quats for short. Overall, this compound is better for applications requiring less toxic disinfectants and smell as in the food industry.

Note: As a pool service guy, I never used algaecides for swimming pools. They are expensive, marginally effective, and can get in the way of how chlorine works during basic swimming pool maintenance chemistry.


As a pool guy, the best way for me to describe calcium is that it’s a metal. It’s monitored in swimming pools only because too much or too little of it can damage the pool’s surface. That’s it.

Everything is relative, so calcium hardness can affect the pool’s water when the conditions are favorable (See Langelier Index)

The simplest explanation is that if the water doesn’t have enough calcium in it, then the water will aggressively seek it and get it from anywhere it can. Conversely, if the water has too much calcium, then it will try to get rid of some of it in any way it can.

This is most important for concrete pools because the wall’s finish will have some calcium in it, so the water can damage the surface by extracting it out of the walls. If there’s too much calcium in the water, it will deposit it on the cement finish in the form of scale or staining.

Note: Above ground pools have vinyl-lined walls. This means that calcium levels are not as important as it can’t damage the vinyl surface when aggressive. You may read that vinyl can be damaged by water seeking calcium, but that is just theory.


Some pool chemistry products use minerals as a disinfectant in swimming pools. To my knowledge though, minerals don’t oxidize (get rid of) what has been killed.

In theory, using minerals as a sanitizing alternative to chlorine looks really good on the internet and paper. The problem is that the internet isn’t a real place. In the real world, minerals are only marginally effective at maintaining swimming pools.

The two main minerals/metals used in swimming pools are copper and silver. I have used both to help get rid of black algae in concrete pools and they work well for that. Silver is more expensive, but I like using it over copper because copper can create staining.

Although I used copper and silver to treat specific conditions (black algae) in concrete pools, I wouldn’t recommend it as a constant product for maintenance. It doesn’t replace anything, so what’s the point?


This sounds like some high-tech way to maintain a swimming pool, but it’s not. Basically, it’s a device that has a metal block(usually copper) with some electric wires attached to it. When the block is charged with a small amount of electricity, the copper breaks down a little and goes in the swimming pool as an ion.

These copper ions will seek out algae and attach themselves to them and the algae will die.


You’ll read that ionizers will prevent algae growth. Yeah, no it doesn’t. It only kills what is already present in the water. This means that ionizers only do what chlorine already does. Now, if it (or anything else truly prevented algae from initially growing, then you’d really have something worth having.

Ionizers also don’t oxidize what it kills, so guess what? Even if it did as good a job at killing as chlorine does, you would still need an oxidizer for the pool.

Copper ionizers can also cause a build-up of copper in the water which can cause some staining under the right conditions. And that’s never fun.

D.E. (Diatomaceous Earth) Powder

This is used only if you have a D.E. type filter, and is in no way an aid to pool water chemistry.

DE powder is absolutely needed if you have a DE type filter. I say this because it’s common for people to not know that they have to add this powder to their filter properly, and their filter won’t work and get clogged up quickly.

Some will use DE powder as an aid in their sand type filter. I’m not a fan of doing this. Most of the time when this is done, the DE powder will only aid in clogging the sand up and the filter ultimately won’t filter as well.


This is another product that a pool service guy who knows what he’s doing would never use. This product just makes some dead things in the water clump together so they can be caught by the filter easier.

Experienced pool guys don’t use a clarifier because it doesn’t do much when you understand the concept of how to use chlorine. The only time that I’ve used a clarifier (other than during my first year of cleaning pools back in the 80s) is when there was a bottle of it in a start-up chemical kit. I’d pour it in a pool because that’s the easiest way to dispose of it.

Some pool owners use this product often and swear by it. To them, I say “Cool man. It’s good that you found a formula that works for your pool”. I’m not one to argue with success.

Stain Removers

When dealing with above ground pools, stain removers won’t work well. Overall, they really don’t work well in any surface type pool.

After having my pool maintenance business for a few years, I once decided that I would learn about removing stains in pools and maybe specialize in it. It didn’t take long for me to abandon that idea.

There are many ways a pool surface can stain. Most of the time, it’s related to metals in the water but can be from many other factors too. When I was learning about stain removal, Jack’s Magic line of products were the best.

During my journey down the rabbit hole of eliminating pool stains, I eventually learned one thing – “There is no guarantee that any product will successfully remove stains”. This is not to say that many stains can be removed. They can. Just don’t assume success just because of what the product claims or anyone else’s success with their pool’s stains. Each pool and situation is different.

If you do try some stain remover products, be real good at following the directions. Things like timing, PH, and other chemical levels can make the difference between success and failure.

Scum remover/ Tile cleaner

For the most part, tile cleaners work pretty well. Some “scum” lines cannot be completely cleaned away though as there may be some etching involved.

Above ground pools with very old scum lines cannot be cleaned as the printing on the vinyl may have been discolored.


If you have read a lot of the above, you may have seen a pattern. The pattern is that most of these products are not necessary and not used by pool professionals like me.

After about five years or so of servicing pools, I learned that successful pool chemistry was more simple than complex. It really comes down to chlorine level management. This is why most specialty pool chemicals are not needed.

There are some basics that must be present for good pool water management like a good pump and filter running long enough every day, keeping the pool somewhat clean, and not having to replace the water much due to a big leak.

And once again, I will never argue with success. If you have a process that works well for you and your pool looks great, then who am I to say you are doing it wrong?


Dan writes with the knowledge of having 35 years (and counting) in the above ground pool industry.

2 thoughts on “Above Ground Pool Chemicals (Defined)

  1. I was told that baking soda, chlorine and shock is all I need…I got the Frog system…but this year I have bought so many chemicals to get rid of green algae…
    Vacuuming everyday…chlorine high today..can you help
    Thank you
    Tj Harmon

    1. The best way that I can help is by having you read this article: https://abovegroundpoolsknowitall.com/getting-a-green-above-ground-pool-clear-again/

      It explains the way that you should cycle your chlorine level. Get this basic down and you’ll never feel out of control of your pool again.

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