Whether you’re battling algae now or vigilant at preventing it, algae is definitely a thing for pools and hot tubs.

As General Sun Tzu said hundreds of years ago,

“Know your enemy and know yourself; in a hundred battles, you will never be defeated.”

Make sure you know all about algae. If you know what makes it grow and how to prevent it, you’ll be on the offense instead of the defense.

And if you know all about algae, it won’t take you by surprise. Start with this quick quiz:

True or False:

1. Algae’s perfect environment is hot weather.

True, but with exceptions! Algae can grow in virtually any environment that has carbon dioxide, sunlight, minerals, and enough water – even very cold climates. The limiting factor in algae growth is often sunlight or minerals. When sunlight is limited, some kinds of algae can take in organic substances, like plant matter, as food.

Hot weather offers algae opportunities. Warmer temperatures prevent water from mixing, allowing algae to grow thicker and faster. Warmer water is easier for small organisms to move through and allows algae to float to the surface faster. Algae blooms absorb sunlight, making water even warmer and promoting more blooms, in other words, it grows fast in warm sunlight!

A set of stairs into a pool are infested with green pool water which indicates the presence of algae.

2. Algae grows only in sunlight.

False. Algae are a living aquatic creature and it’s true that it multiplies rapidly on warm, sunny days. Algae contains chlorophyll and uses photosynthesis to grow; it takes in carbon dioxide and expends oxygen as a byproduct. Algae can grow in the shade or sun, but most pool algae strains need some light to grow.

3. Like brushing your teeth regularly to prevent cavities, brushing the sides and surfaces of your pool regularly will help prevent algae.

True. Most types of Algae need a surface to cling to; a good brush will prevent this. Make it a routine and keep algae away.

Man's hands reaching over pool water with an extended brush to clean the pool's surfaces

4. It’s important to keep your pool’s pH balanced; high pH levels are an algae invitation.

True. Algae thrives in water with high pH levels. For most algae growth, an optimum pH is between 8.2 and 8.7. A pH level that is neutral or lower can help decrease algae growth.

Find out more about pH balance here. Check out the FROG^® Water Balancing Guide for help or use your FROG Water Care App.

5. Ketchup and mustard algae?

Half true! Mustard algae is known as yellow algae. Just like mustard can stain your favorite white shirt, mustard algae can ruin your poolside.

It’s not a common algae, but like all algae, it’s persistent. It’s usually found in southern climates and can be mistaken for sand, dirt or a stain in your pool.

And worse, it’s chlorine resistant. It likes to attach itself to pool walls and other items even outside your swimming pool; it can piggyback on pool toys, equipment and even your swimming suit.

Brown wicker basket filled with laundry, including bright-colored towels and swimsuits.

To get rid of it: Wash your swimsuits with laundry detergent, and thoroughly rinse them. Also thoroughly clean all pool equipment and toys – anything that goes into your pool – with a clean cloth and a chlorine-based cleaner.

And for your pool, test your pool water with FROG Test Strips and balance it accordingly.

Properly balanced water will help your pool shock work more effectively. Contact your dealer. You’ll need to shock it and your dealer will advise you on the best shock and how much to use.

6. You don’t need to wash swimsuits, or pool floats, it’s all water so its fine to go straight from a lake, river or pond and into the swimming pool.

False. Algae can get into your pool water in many ways, like on someone’s swimsuit or a float or toy brought into the pool. If people get pushed in, jump in or forget their swimsuit, street clothes can easily carry algae particles.

Even a dog who’s just having a little fun in the pool with you can be the algae carrier. Algae’s microscopic particles will take a ride on almost anything to get into your pool. Once it’s there, you need to act quickly.

Test your water to keep it balanced. Keep debris out… along with brushing the pools sides and bottom, scoop out all organic matter asap.

A brown Pomeranian sits by the edge of a pool and looks up at the camera

Clip Art of a grey clock displaying the time 4 o'clock

7. A small bit of algae won’t hurt, it can wait until you have time to clean it.

False. Don’t wait to take care of algae. The longer you wait, the more it grows, and it can get out of control before you realize it. Then it will cost more time and more money to resolve it.

These are a mere few facts about algae, you can read volumes about algae – more than 20,000 strains exists! But these few facts will arm you in the battle against it. Even better, an easy way to prevent algae is to use FROG BAM^® – it guarantees no algae for 90 days! And it’s easy to use. Check it out.

If you have algae in your pool, check out Diagnose a Problem on our website or your FROG Water Care App. Or call us at 800-222-0169, we’re here to help!

Bottom line, if you know what causes algae and how to prevent it, you will win those “hundred battles.”