"> How to Add Chemicals to an Above Ground Pool – Above Ground Pools Know it All

How to Add Chemicals to an Above Ground Pool

Regardless of any marketing pitch with certain pool chemistry add-ons, if you have a swimming pool, you’re going to have to add chemicals. This cannot be avoided.

Adding chemicals to above-ground pools is a little harder than with ingrounds. For one thing, you have to potentially lift the container higher to dump the contents over the wall.

Another issue with above-ground pools is that they have vinyl liners which can get damaged by direct exposure to certain chemicals.


In the world of swimming pool chemistry, chlorine is the absolute king. There are some alternatives to using chlorine, but they are expensive, temperamental, and don’t work as well.

For these reasons, chlorine is used in more than 95% of all pools. Chlorine is very corrosive, so handling it requires some rules and safety. For more information on exposure and risk, check out the CDC guidelines on chlorine


Chlorine is added to a pool in two ways – shock and slow-dissolving tablets.


1. Wear clothes you don’t care about

Liquid chlorine loves to eat cotton. If you are wearing something with cotton, one drop(from a splash) will make a hole in your clothes.

If you are wearing clothes made just partially of cotton, the chlorine will dissolve the cotton in the fabric and leave the rest alone. This will still give you a hole.

When I did pool service, I eventually learned to wear non-cotton shorts and shirts. The chlorine still stained my clothes, but since there was no cotton, I wouldn’t get holes.

2. If using granular, dilute completely first

It seems that every year, I have to replace a one-year-old liner due to the fact that the pool owner poured granular shock directly into the pool without diluting it first.

It’s very easy to tell if granular chlorine was poured into a pool as the bottom of the liner will be bleached white. This not only takes the color or pattern from the liner. It also makes it brittle and takes the life out of it.

Dilute your granular chlorine in a five-gallon bucket with water first. Stir the water until there are NO GRANULARS left. Then pour into your pool.

NOTE: I recommend using liquid chlorine for shock. With liquid, you cannot damage the liner.

3. Add directly to pool body, not skimmer

You may read or see someone tell you to put chlorine shock into the skimmer while the pump is running. The logic here is that the chlorine will go through your filter and sanitize it and then disperse quickly in the pool as it will be shooting out of the return fitting into the pool.

I don’t recommend doing this! Although it may not hurt anything to pour shock through the equipment, concentrated chlorine is very corrosive. If for some reason, some of that concentrated chlorine gets trapped somewhere in the system, it may take some life out of it. Plus, you don’t gain anything by doing this, so why do it?

Add your liquid (or completely diluted granular) shock directly to the swimming pool. Just keep the pour from touching the top rails or liner above the waterline, or splashing on anything.

NOTE: You don’t have to broadcast the shock around the pool. You can pour it in one spot and it will very quickly evenly distribute in the body of water naturally. Not broadcasting the shock can help prevent chlorine splashing mishaps.

4. Don’t add shock with swimmers in the pool

Chlorine shock will evenly disperse in the water a lot faster than you think, but you don’t want a kid swimming into an underwater cloud of chlorine as it’s distributing.

In some bigger commercial swimming pools, liquid chlorine is being added all the time even with swimmers in the pool. These are larger pools though and the amount going in is smaller than when you pour a full 2.5-gallon jug into your 11,000-gallon 21’ round above ground.

5. No need to broadcast it. That invites for spillage. Will disburse very quickly

As mentioned earlier, you don’t have to walk around the pool while pouring in the shock. It will do its thing almost as fast by just pouring in one spot.

If you have trouble agreeing with this, ask anyone who has been a pool guy for more than a year or two. Yeah, they aren’t going to risk walking around a pool while spilling a corrosive chemical into it when it doesn’t matter.

6. Store away from anything that can corrode

Even if just sitting there, chlorine is corrosive. Don’t store it in your garage where you have things made of metal that you care about. Keep your chlorine storage outside and in a plastic box so it’s protected from the elements.

7. Liquid chlorine should be used within a month of purchasing

Observation: I have noticed that this is argued on the internet. This is probably because giants like Walmart and Home Depot sell shelved liquid chlorine.

The difference between what is called “liquid chlorine” and “bleach” is usually only the percentage of chlorine it contains. Liquid chlorine contains between 10% and 15% chlorine while bleach contains 5%.

Now when liquid chlorine hangs around for more than a month, its chlorine level drops down (or starts dropping) to about 5%, which is the same as bleach. This means that old liquid chlorine will have half or a third as much of its active ingredient left in it.

This is why I recommend buying your liquid chlorine from a busy pool store in the yellow jugs INSTEAD of the gallon shelf chlorine at Walmart or Home Depot. The chlorine will be fresher which means it will have more chlorine in it.

8. If splashed on, wash with soap and water immediately

If you get chlorine on your skin, it will irritate you in a couple of minutes. The sooner you can wash it off, the better.

During my years as a pool maintenance guy, I learned to wash chlorine on my skin quickly. The longer it stays on your skin, the more irritating it will be.

9. If splashed in the eye, flush with water or saline immediately

Believe it or not, it’s very common for people to get an upward splashed drop of chlorine directly into an eye. And that sucks.

This is not an emergency situation, but you will instinctively want to wash your eye out ASAP. Keep your eye as open as possible while splashing water into it. This will do a good job of flushing out the chlorine as long as it’s done quickly.


1. Do not put in skimmer

When I did pool maintenance on concrete inground pools, if the pool didn’t have a chlorinator or floater, I would place the chlorine tabs in the skimmer basket. This was not ideal but was ok.

With above-ground pools, you don’t want to keep chlorine tablets in the skimmer.

This is because when the pump is off, the water in the skimmer just sits there. And if there is a tablet in the skimmer basket, then it will super, super chlorinate just that water.

Chlorinated water is much heavier than non-chlorinated water. This means that the heavier chlorinated water in the skimmer can get heavy and travel out of the skimmer opening and into the pool.

This by itself is not a problem, however, this heavier chlorinated water will hang out too long directly in front of the skimmer and bleach out the liner where it meets the skimmer faceplate.

I have had to replace liners because the portion of the liner directly under the skimmer was damaged from heavily chlorinated water seeping out of the skimmer that had tabs in it. Not good.

2. Use a floating chlorinator. Inspect floater condition

Ninety-plus percent of all above-ground pools use a floating chlorinator to hold their tablets in. This is a great way for these slow-dissolving tablets to distribute a small amount of chlorine continuously into the pool.

Floaters don’t last forever though, so you should make sure that they are in good condition. Why? Because they can crack and the bottoms break, which will allow the tablet to fall out and rest on the bottom of the pool.

And you absolutely don’t want a chlorine tablet resting directly on your pool’s liner anywhere!

3. Be careful when opening your tablet container

Chlorine tablets don’t gas off too much, so it’s usually not too bad when opening the container to grab one. Sometimes though, some moisture will get in the container (either from the elements or wet hands prior).

When even a little moisture gets into the tablet container, it can build up gas. And that gas will hit you very hard when you open the container.

As a pool maintenance guy for 16 years, the worse issues I had with handling pool chemicals was with opening a tablet container that had some moisture in it.

The chlorine gas has knocked me back and down to the ground. It’s also given me such a bad headache, that I would have to quit working and go home for the day.

Don’t play around. When opening your container to get a tablet, unscrew and pull off the lid slowly with your head far away.

4. Ideally, use rubber gloves to handle

This isn’t big deal, but when I grab a chlorine tab and put one in a chlorinator or floater, I immediately wash off my fingers (that touched the tab) with water.

If you wear (rubber) gloves or grab the tab with something, then you won’t get any chlorine dust on your hand, which is good.

5. Store away from anything that can corrode

Tablets with secure containers won’t have as much chlorine gas escaping as liquid shock will, but there will be some. Keep your tablets out of the elements (you don’t want them to get wet. See #3) and stored away from anything that can corrode.


Now that I covered the king of pool chemicals (or the “they” and “them” if you’re into pronouns), it’s time to cover all others.

1. Muriatic acid (for reducing PH or reducing TA)

  • Can be poured in one area for reducing pH. Or if lowering the total alkalinity (TA), broadcast slowly around the pool some.
  • Be careful when using as the fumes can be very strong. You may want to pour downwind or hold your breath when pouring
  • If you get some on your skin, just rinse off immediately with water. Water will neutralize the acid very quickly.

2. Soda ash/ sodium carbonate (for raising pH)

This is probably the most harmless chemical that you use with a swimming pool. You can dilute it first in a bucket or pour directly into the pool. It will eventually dissolve and disperse on its own. Soda ash will not harm the liner.

3. Sodium bicarbonate (for raising pH or TA)

“Bi-carb” as pool guys call it is also a somewhat harmless chemical to work with. Dilute first with a bucket of water or add directly to pool

4. Sodium bromide (Yellow Treat/ Yellow Out)

This is the only algaecide-type product well-experienced pool guys will use. It is needed to kill yellow/mustard algae.

Follow the directions when using sodium bromide. This usually will tell you to add the product, then brush the pool, then shock, then run the pump continuously for 24 hours.

5. Cyanuric acid (Stabilizer) (to help keep a chlorine level)

This is another fairly easy chemical to work with. I recommend diluting it in a bucket of water before pouring it into the pool. You can pour in one spot (don’t have to broadcast it).

6. Dry acid (Sodium Bisulfate) (for lowering PH)

Pool guys prefer muriatic acid to lower pH, but this product is common in chemical start-up kits and is easier to store.

I recommend diluting this chemical in a bucket of water before introducing it into the pool.

7. Metal out (getting metals out of the pool water)

Follow the directions for this product. There are some different types, so just make sure you diluted any granular versions first.

Usually, metal out products work best when broadcasting around the pool when adding.

8. Algaecides

The only time I ever used algaecides is when I got them for free and had to dispose of them. Putting them in a swimming pool is easier than having to pour them out somewhere.

Follow the directions for using any of these products. Make sure to dilute first if not in liquid form. Sometimes they will want the chlorine to be a certain level in the pool. Do what it says.

9. Calcium (For increasing calcium)

Above-ground pools don’t need calcium. Some will choose to believe the internet or their pool store and buy it anyway. Hey, that’s cool. Be you.

Calcium should be completely diluted in a bucket of water before introducing into your pool. This will take some time as it doesn’t dissolve super fast.

Take a portion at a time and dilute by swirling the water in the bucket until the calcium flakes are completely gone.

NOTE: Calcium will heat the water in the bucket up when dissolving. Don’t worry about that. It won’t get too hot.

10. D.E.(Diatomaceous Earth) (used with a DE filter only)

This is only used if you have a diatomaceous earth-type filter. The correct amount is added through the skimmer when the pump is on. This finds its way to the filter where it coats the grids on the inside.

Follow the filter directions for changing the DE powder.

Diatomaceous earth or DE powder is a snow-white powder that seems harmless, but it isn’t.

Warning: DE powder is extremely toxic to breathe! And don’t get any in your eye.

When dealing with DE powder, make sure not to breathe it in. And don’t let any of the fine dust get on your skin and especially in your eyes.

11. Clarifier

Clarifier is another specialty chemical that experienced pool guys never use. Many people use it though with some degree of success ( I guess)

Follow the directions for this product. If not in liquid form (it usually is) then dilute in a bucket of water before pouring it into your above-ground pool.

12. Stain removers (for removing surface stains)

Most stains cannot be taken out, but that shouldn’t stop you from trying. Stains in concrete pools can sometimes be successfully removed with these products (if used early). Sometimes!

Above-ground pools that have stains on the vinyl liner often cannot be removed.

Follow the directions very strictly with these products. It’s often a process of timing plus the chemical in order to have success.

13. Scum remover (for cleaning the water/tile line)

The water line in above-ground pools can get a nasty film on them. Use this product with a medium scrub brush (scrubby) type applicator. Follow the directions well.


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

14 thoughts on “How to Add Chemicals to an Above Ground Pool

  1. It rained buckets here last night. I released a lot of water because it was overflowing in the skimmer. I checked levels with liquid test. Ph is high but reading no chorine. Do I fix the ph first or do I shock it then add ph down later?

  2. What is the most reputable salt chlorinator to get? Will making a zinc anodizer really prevent the notorious rust ? I’ve read so many articles on all of this but cannot really find a straight answer. Thanks in advance for any advice you may reply with!

    1. I think the Hayward SCG is best, but can’t say for sure as they have recently changed the design. And here’s my article on what salt water does (or doesn’t do) to an above ground pool https://abovegroundpoolsknowitall.com/the-real-truth-about-salt-water-above-ground-pools/

  3. New above ground pool owner here. Having issues figuring out these chemicals. My Ph level is. 8.4 my alkalinity is 240, total hardness is 500 says 0 for chlorine both total and free. And stabilizer is 50. I have shocked the pool, have little water bugs swimming around, someone told my husband to add a 32oz bottle Of algaeside. So he does . I have been brushing my walls because of some slimy stuff I can’t see all over the place. I have spent a crap tone of money on chemicals. What can I do. Water is a tad cloudy too… any advise is greatly appreciated.

    1. Trying to explain pool water chemistry here would take too long. I’m planning on writing a couple of articles about it after my season (I install pools in the real world) so please check back for those.

      In the meantime, this article can give you some basic understanding. https://abovegroundpoolsknowitall.com/getting-a-green-above-ground-pool-clear-again/

      1. Thank you so much for getting back to me! I get the excavater in 2 days and I couldn’t have even started it without all of this information on your site. thank you so much.

  4. Can you tell me why you’re not a fan of the product you mentioned above. Do you have any other suggestions for somebody that can’t be in chlorine?

    1. I’m sorry but I think baquacil is your best bet for avoiding chlorine. I will say that many think that they cannot be in chlorine, but they can. I’m sure there are super, super rare exceptions (there are to everything), but chances are you can be in chlorinated water with no issues. It’s the combined chlorine that is the problem for people, not free available chlorine.

      Some have said that they are allergic to chlorine. This is not possible as our bodies make and need chlorine to survive. I’ve had people tell me that they are sensitive or allergic to chlorine, so they can only go in salt water pools. What they don’t know is most salt water pools have higher levels of chlorine in them than non-salt pools. It’s really about avoiding combined chlorine building up in the water.

      I wish I had a better alternative for you, but nothing beats chlorine for pool maintenance.

  5. I live in Arizona, all of my levels are right on, but I am having a hard time keeping my total/free chlorine up.

    Within a day it’s right back to nothing. What do I do? Stabalizer is in and reading at level.

    I have an 18ft round Bestway pool, approx 6000 gal

    1. When I had my pool service, I had some pools that would have zero (or close to) readings every week in the summer. These were some of my healthiest, most trouble-fee pools on my routes. Having your chlorine level go to zero on a regular basis in the summer is a good thing.

      With that said, if you aren’t able to keep enough of a chlorine reading throughout the week, then add another chlorine tablet or two to your floater. That should take care of that.

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