Pool School

Matt Giovanisci: 00:00

Everyone, and welcome to Pool School by Swim University where we help you keep your pool clean and clear all year. My name is Matt, the founder of swimuniversity.com. And on this episode, we're talking about how much chlorine your pool actually needs. Let's dive in. You want more help taking care of your pool?

Matt Giovanisci: 00:30

Be sure to grab our free pool care cheat sheet at swimu.com/cheat sheet. Usually, it only takes a few tablets or a cup of granules to keep your water sanitized, but it all depends on the size of your pool and what type of chlorine you buy. First, what are the right chlorine levels for your pool? Your free chlorine should be between 1 and 3 parts per million with 3 parts per million being ideal. Unfortunately, chlorine tends to fluctuate.

Matt Giovanisci: 00:57

Things like debris, contaminants, rain, extra swimmers in your water, and even sunlight can cause your chlorine levels to drop. Testing your water and replenishing your chlorine weekly will help you keep your levels in check. Now before we calculate how much to add, you'll need to choose what type of chlorine you want to use. There are 3 common forms. There's granules, tablets, and liquid chlorine.

Matt Giovanisci: 01:20

Granules, which are made of dichlorchlorine, are added directly to the water by broadcasting the granules over your pool surfaces. And that means you'll have to add it by hand each week, but it gives you more control over dosing. This type of chlorine is also stabilized, meaning it contains cyanuric acid or CYA. And CYA helps protect your chlorine from breaking down in direct sunlight. Then there's chlorine tablets.

Matt Giovanisci: 01:46

Now these are made of trichlor chlorine and come in 3 inch pucks or 1 inch tablets. They're added to a dispenser like a floating or an automatic chlorinator. Tablets are more hands off than granules, but the dosing is a little bit harder to control. Things like water temperature and how often you you run your pump can affect the rate that your tablet dissolve. And like granular chlorine, chlorine tablets also contain cyanuric acid, which helps to prevent the chlorine from breaking down in the sun.

Matt Giovanisci: 02:17

But CYA can quickly build up in your pool when you're using tablets, so be sure to monitor your CYA levels. And then finally, there's liquid chlorine. Now liquid chlorine is usually only about 10 to 12% of chlorine by volume. That's about twice as potent as household bleach, but it's a lot less potent than chlorine granules or chlorine tablets. Liquid chlorine is also unstabilized, meaning it does not contain cyanuric acid.

Matt Giovanisci: 02:48

And that means it will break down in direct sunlight if you supplement it with chlorine stabilizer, aka cyanuric acid. Okay. So you've got your chlorine. There's one step that you need to do before adding chlorine to your pool, and that's to test your water and balance your pH and alkalinity. Getting these levels in range first will help your chlorine to work more effectively.

Matt Giovanisci: 03:08

And knowing where your chlorine levels are will help you decide how much chlorine you need to add. So here's exactly how much chlorine you need to add to your pool. First, you'll need to know your your pool's volume. And make sure that your pump and filter are running before adding chlorine to your water because this will help it circulate and dissolve. For chlorine granules, add 2 or 2 to 3 ounces for every 5,000 gallons.

Matt Giovanisci: 03:33

That's 4 to 6 tablespoons of chlorine. So if you have a 20,000 gallon pool, that's about 7 ounces of chlorine or a little under a cup. Now for 3 inch chlorine tablets, you wanna add 1 tablet for every 5,000 gallons of pool water, and that means about 4 tablets for a 20,000 gallon pool. If your pool holds 10,000 gallons of water or more, 3 inch tablets work great, but they can quickly overwhelm smaller pools. So I would opt for 1 inch tablets, granules, or liquid chlorine instead.

Matt Giovanisci: 04:08

For liquid chlorine, you wanna add half a gallon of liquid for every 5,000 gallons. That means you'll need 2 gallons of liquid chlorine for a 20,000 gallon pool. Now remember, this is for pool grade liquid chlorine. I'm not talking about household bleach, which is not as strong. Now what if your chlorine levels are off the charts, or or what if it's at 0?

Matt Giovanisci: 04:32

If your chlorine level is too high, you wanna stop adding chlorine to the water and see if your chlorine levels drop naturally on their own. If you're not getting a chlorine reading at all or it keeps dropping to 0, well, then it's time to shock your pool. Shocking is a concentrated dose of chlorine that can help bring your levels back into range. But if your chlorine continues to remain low, even after shocking, your cyanuric acid levels may be off, or you might have a chlorine demand issue. So we have some videos on our website that you can check out, if you have a chlorine demand issue.

Matt Giovanisci: 05:10

Now remember, if you need more help with pool maintenance, be sure to grab our free pool care cheat sheet at swimu.com/cheat. And if you found this episode helpful, subscribe for more pool maintenance tips on your favorite podcasting app. And when you do, please leave us a review. Your support will help more pool owners just like you find this show. That's it.

Matt Giovanisci: 05:32

Thanks again, and happy swimming.