A Complete Guide To Pool Alkalinity

Keeping all the chemicals balanced in your pool can be a little tricky. And pH and alkalinity levels are sometimes the most unstable.

This is because anything from a few extra leaves to a hard rainfall can disturb it. And your job of getting it back in balance can take a little time.

To help you out with this, here’s a quick rundown of everything you need to know about pool alkalinity and what to do when it gets out of range.

What is pool alkalinity, total alkalinity and ph?

When someone talks about pool alkalinity, they’re actually referring to total alkalinity (TA). That is the total concentration of hydroxides, cyanurates, dissolved carbonates, and bicarbonates in the water. 

All those substances are alkaline substances, meaning they come in higher on the pH scale. This scale ranges from 1 to 14, the lowest being extremely acidic and the highest being extremely alkaline (or basic). 

(image credit: https://kylelockwoodsciencerevision.wordpress.com/2016/11/29/acids-and-alkalis/)

Because alkalinity and pH work closely together, many people mistakenly think they’re the same thing. But they’re not. 

PH is a measure of how acidic or alkaline the water is, while alkaline is measured as an actual substance in parts per million (PPM)

Make sense?

Why is pool alkalinity important?

Alkalinity is sort of a little helper to the pH balance in your pool. But it’s an extremely important part of the partnership.

PH balance is actually one of the most important elements to clean and healthy water. But unfortunately, it’s very sensitive and needs a stabilizer. 

That’s where alkalinity comes in.

Alkalinity prevents sudden changes in pH levels and keeps it in normal range. Without it, you can face a whole slew of problems that are very difficult to control.

Low alkalinity can cause huge pH swings. This can cause your chlorine to stop working as well, corrosion, green water, itching/burning eyes and skin, surface etching, and pool staining.

High alkalinity will typically cause your pH levels to spike. This can cause cloudy water, itching/burning eyes and skin, and scaling. 

All of this can lead to equipment damage and poor water circulation.

How do alkalinity and ph relate to water chemistry?

Have you ever wondered what pH stands for? It’s actually the “power of Hydrogen,” or “the measure of the concentration of hydrogen ions in a solution. 

When this goes up, pH levels go down. And when it goes down, pH goes up. 

But the reason it’s all so important is because pH levels are what determines how effective the chlorine will be in the water. 

When pH levels are on the low side, the chlorine is very strong, so you might think the lower, the better, right? Not necessarily!

If the chlorine is too strong, it will burn off too quickly, but cause a lot of damage in the process (see above for problems caused by low pH). It’s also very uncomfortable for swimmers.

And of course, when pH is too high, the chlorine can be rendered almost useless.

Testing Alkalinity Levels: What is the right amount of alkalinity

The proper range for total alkalinity in a pool is 80-120 PPM.

You should be testing this, along with your other chemicals at least once a week. More if you’ve had any imbalances that you’re trying to correct.

What causes alkalinity to rise or fall?

Lots of things can throw off your pool chemistry, and alkaline levels are no exception. 

Usually, alkalinity is primarily affected by the pH level in the water. And vice versa.

Common causes of low alkalinity are things like rain or body fluids. In other words, anything acidic.

It can also be caused by using too many chlorine tablets that have a very low pH level.

Common causes of high alkalinity are body lotions, sweat, too much pool shock, or a high-alkaline water source.

When the alkalinity levels change too drastically, you’ll need to do something to balance them ASAP. 

How to raise pool alkalinity

If the problem is low alkalinity, you’ll have to add something to the water in order to raise it.

This is actually a pretty simple fix. Regular ol’ baking soda (sodium bicarbonate) will usually do the trick. Sure, there are some products out there just for this purpose, but seriously, baking soda is all you need.

You can’t beat the price and you can actually order it in larger bags so you don’t have to empty a ton of those little boxes.

There is also another option that’s even cheaper — soda ash (sodium carbonate). It’s a little less effective but it’ll do in a pinch. Keep in mind this can also make your water cloudy, though, so be sure to run your filter for a while after you use it.

To use baking soda for this purpose, you’ll have to figure out how much you need. 

About one and a half pounds per 10,000 gallons of water should raise the alkalinity about 10 ppm. But to keep from lowering it too much, it’s a good idea to start out with about half the amount you think you’ll need to see if that works.

Once you’ve measured out the amount to use, spread it all over the surface of the water with the pump turned on to circulate it. Wait about six hours and then test your pH and alkalinity levels again. 

Repeat this process as needed until these levels are within normal range.

How to lower pool alkalinity

Lowering your pool’s alkalinity levels can be a bit tricky, especially if you keep having the same problem and you’re not sure why.

If, however, high alkalinity is not usually an issue, you can use either muriatic acid or dry acid (sodium bisulfate) to bring it down.

Dry acid is a little safer to handle than muriatic acid, but both can be fairly dangerous if you’re not careful. 

If neither of these options appeal to you, you can also drain off some of your water and replace it with fresh water. This is a much more natural choice if you don’t want to add extra chemicals to the pool. 

If high alkalinity is a frequent problem in your pool, you may need to do some investigating. A lot of times, people with this issue find that their water source has a lot of alkaline in it.

To find out, you can use your own pool testing kit to check it, or you can take it to your local pool shop for testing.

An easy fix for this might be a water hose filter. These will help remove a lot of the contaminants that affect pH and alkalinity from your water supply as it enters the pool. 

How do you raise the ph in a pool?

Since pH and alkalinity levels are so closely related, you can do the same things to lower one that you do the other.

Baking soda or soda ash are really the only products you can use to get the job done. See our advice under “How to raise pool alkalinity” for detailed instructions.

How do you lower pool ph?

The directions for lowering the pH level in your pool is the same as above for lowering your alkalinity. If you can successfully lower one, the other should follow very quickly.

Conclusion

Pool chemistry can be thrown off by so many different factors, that it’s crucial for you to test it on a regular basis. Alkalinity and pH levels, especially, are pretty touchy and often require special attention.

The main way to keep things under control in your pool is to stick to a very strict weekly maintenance routine. This should include testing the chemicals, cleaning out debris, brushing the walls, and vacuuming. 

This way, you’ll notice any chemical imbalances immediately and be able to quickly address them before they get out of hand.