If your pool, spa, hot tub, or water feature is looking unhealthy, with slimy green algae covering the surfaces and turning the water green, a top-quality algaecide will create crystal clear water that is perfect for swimming, relaxing, and the right aquatic environment for your fish and plants.

The 10 Best Algaecides
- In The Swim Super Pool Algaecide
- Kem-Tek Pool and Spa 1-quart Algaecide (Our Top Pick)
- BioGuard Banish 1-quart Algaecide
- Algaedyn
- Eclipse3 Pool Algae Control System
- Clorox Pool & Spa Xtra Blue Algaecide
- SeaKlear Yellow Klear Algae Control
- API Pond Algaefix Algae Control
- EasyCare FounTec Algaecide and Clarifier
- Pool RX Algaecide Blue Treats
Our Top Pick for the Best Algaecide

Our top pick for the best algaecide is the Kem-Tek Pool and Spa 1-quart Algaecide. Eliminate stubborn algae from your pool and spa with the highly effective Kem-Tek Pool and Spa algaecide. With a highly concentrated formula, Kem-Tek is the perfect choice for any pool or spa owner as the algaecide has a triple action modus operandi; it treats existing algae and prevents any new spore growth, and clarifies the water so that you can use your pool and spa all year round.
Check the price on AmazonEliminate Algae With a Quality Algaecide
Having your own swimming pool or pond or spa can be a delight; lazy days spent cooling off in the hot summer, hosting pool parties, chilling out in your bubbly hot tub, and water features such as a pond or fountain add a special touch of restful aquatic ambiance to your garden. However, unfortunately, having these sorts of water-based environments can cause algae to grow if the pool or water feature is not properly maintained.
This is where a quality algaecide and proper maintenance come to the rescue – it will eliminate algae and create a sparkling clean and healthy pool, spa, or water feature that you can enjoy with friends and family forever.
What is Algae?
Algae are living organisms that grow in an aquatic environment such as a river, stream, or lake. Wherever there are bodies of stagnant standing water, algae thrive. Once the algae have dried out, the spores are carried by the wind and are deposited in our backyard pools. They also love to grow in badly maintained pools, in pool equipment, and in swimsuits that have not been cleaned and dried properly.
As well as making a pool’s surface that sickly green color and create slimy deposits and unsightly staining on the sides of a pool or pond, algae can suffocate your plant life and fish and allow harmful bacteria to form in the watery depths.
4 Types of Algae
There are 4 main types of algae:
- Green Algae (Chlorophyta)
- Yellow Algae (Phaeophyta)
- Black Algae (Cynaophyta)
- Pink Algae (PaecilomycesLilacinus)
What Causes Pool Algae to Occur?
The main instigators of algae growth are;
Water Temperature – Pool algae prefer warm water to breed and thrive.
Sunlight – Like plants, algae contain chlorophyll, and through a process of photosynthesis they bloom in sunlight.
Nitrates – Fertilizers that contain nitrates are what algae love to eat. If these are introduced to your pond, algae will grow at an accelerated rate.
pH balance – Having the wrong pH balance will affect the performance of the algaecide so before you add an algaecide, make sure you have the correct pH balance.
Filtration system – If a body of water does not have proper circulation, it will create the perfect environment for algae to grow. Your pool needs a good filter and your pond or water feature needs an adequate filtration system to create the proper amount of aeration.
Tips For Maintaining Your Pool or Spa
- Clean out leaves and debris from your pool or spa or pond.
- Brush any algae off the surfaces of the pool.
- Clean out the filters and circulate the water by using the filter pump regularly.
- Your pool, spa or water feature is now ready for a top-quality algaecide.
How to Choose the Best Algaecide
Algaecide can be used in a swimming pool, spa, hot tub, indoor and outdoor fountains, water features, ponds with or without fish (depending on the product), and indoor fish aquariums. They come in either a liquid formula such as the Kem-Tek Pool and Spa 1-quart Algaecide or granules such as the Eclipse3 Pool Algae Control System. Active ingredients can either be copper, silver, sodium bromide, or poly(oxyethylene dimethylamino) ethylene dichloride. For an easy algaecide solution, the PoolRX algaecide unit comes with algaecide inside and can be placed directly into your pump basket or skimmer.
Copper Algaecide
Copper-based algaecide is the most common type of algaecide and it is usually the cheapest. Algae hate copper, which makes this algaecide very effective. The problem with copper is that algae can develop a resistance to it and if the algaecide has a higher amount of copper it can cause staining on the pool’s surfaces. Copper-based algaecides that have a smaller amount of copper, such as the Clorox Pool & Spa Xtra Blue Algaecide, are anti-staining. However, you may have to use the product frequently to get the desired effect and use it in conjunction with other products.
Silver Algaecide
Silver works the same as copper but it is more expensive. Silver algaecide like Algaedyn is especially effective at killing black algae which is notoriously hard to kill especially when it has gotten into the cracks of your pool. Like copper, algae can develop a resistance against silver but this type of algaecide can also be used with other products.
Sodium Bromide
Sodium bromide algaecides, such as SeaKlear Yellow Klear Algae Control, are the choice of many pool professionals. Technically sodium bromide is not an algaecide but more of a sanitizer or an algae inhibitor but it is a great choice as it is a dual-action solution that kills algae and bacteria and it works in conjunction with chlorine.
Other types of ingredients that are used are poly(oxyethylene (dimethylamino) ethylene, which is more effective at preventing algae, but it does a good job of killing small amounts of algae.
There are very good natural algaecides alternatives such as the Eclipse3 Pool Algae Control System, but they are more effective on small amounts of algae.
10 Best Algaecides – Reviews
1. In The Swim Super Pool Algaecide

This superior highly concentrated fast-acting copper In The Swim Algaecide can be used to eliminate and control most types of algae in just a couple of hours. The 1-quart bottle contains a non-foaming, no odor formula that includes a potent 23.5% Copper Triethanolamine Complex and 7.1% chelated copper which makes this a powerful and effective treatment for algae.
To start the algaecide process, the start-up dosage is 4-ounce per 10,000-gallons, and for ongoing maintenance 2-ounce per 10,000-gallons of water per week. Once you have added the product, you can swim in the pool straight away.
If you have black algae, you will have to combine this treatment with a chlorine algaecide.
Pros
- Excellent quality
- Great value for money
- High concentrated copper-based formula
- Provides superior algae-fighting power
- Highly effective
- Fast acting
- Can be used on most types of algae
- Ideal for spring pool openings and ongoing pool maintenance
- Non-foaming
- No odor
- Can swim straight after application
Cons
- May need to combine with other products to kill black algae
- Can cause staining if too much of the product is used
- Not recommended for use in well water
- Super Algaecide cannot be used in the state of California due to State Restrictions
2. Kem-Tek Pool and Spa 1-quart Algaecide

If your pool, spa, or fountain is playing host to unsightly green algae, the Kem-Tek Pool and Spa 1-quart Algaecide bottle will kill the algae and prevent any new spores from developing. The concentrated non-foaming, non-staining algaecide contains 60% poly [oxyethylene (dimethylamino) ethylene (dimethylamino) ethylene dichloride] as its active ingredient and it is safe for all pool and filter types. It helps to clarify pool water and it is salt-system compatible.
This long-lasting algaecide is highly effective and works within a couple of hours but if you have a lot of algae, on the walls, floor, or steps of your pool or spa, you will have to brush the algae off first and then apply the algaecide. You can even pop some into your fountain or water feature just as long as it does not contain any fish.
Kem-Tek has helpful tools and tips on its website if you have questions about its product and a How to Test Your Pool Water guide.
Pros
- Excellent quality
- Great value
- Safe to use for all pool and filter types
- Highly effective on most types of algae
- Fast-acting
- Helps to clarify pool water
- Can be used for fountains and water gardens that have no fish
- Long-lasting
- Non-foaming
- Salt-system compatible
- Ideal for treatment and prevention
- Website has pool care tools and tips and How to Test Your Pool Water guide
Cons
- Not very effective at eliminating mustard algae
- Algae needs to be brushed off first
- May need to use additional treatments for large infestations
3. BioGuard Banish 1-quart Algaecide

The BioGuard Banish 1-quart Algaecide is a highly effective preventative algaecide that contains copper, which makes it one of the most powerful treatments for treating all types of stubborn algae such as green, mustard, and black algae. It is fast-acting, non-foaming, non-staining, and when used as directed, you will see results in just 24 hours.
It is recommended for use with all large chlorinated, bromine, and saltwater pools with all surface and filter types, and pH levels.
Once you have removed settled algae, applied BioGuard Banish, you can start swimming in the pool 30 minutes after the treatment. BioGuard works best when algae is first appearing but if you have a large algae infestation, you may have to use this algaecide with other pool chemicals.
The BioGuard Banish algaecide is available in a 1-pack and a 2-pack.
Pros
- High quality
- Affordable price
- Great value for money
- Highly effective
- Ideal for use on green, mustard, and black algae
- Fast-acting and long-lasting
- Non-foaming
- Designed for all chlorine pools, bromine pools, and saltwater pools
- Can be used with all surfaces
- Perfect for all pH ranges
- Available in a 1-pack and a 2-pack
Cons
- Can stain pools that have a vinyl liner
- May need to be used with other chemicals for extra stubborn algae
4. Algaedyn

Algaedyn is a concentrated algaecide that is specially formulated for the control of those hard-to-kill pool pests: black algae, and mustard algae.
The main ingredient is colloidal silver which is a highly effective agent that rapidly kills and prevents the growth of the most deeply rooted algae cells. You can use the Algaedyn for all pool types and it is non-foaming and odorless. It is very easy to use, just add the Algaedyn into the filter, in the lead to the filter, or directly into the skimmer. Once you apply the algaecide at night, you can swim in your pool the next day.
This algaecide also helps prevent the algae accumulation in the filter so that it stays clean and free-flowing and improves the effectiveness of your chlorine. Algaedyn is compatible with most other chemicals that are normally used in the maintenance of swimming pools and may reduce the need for other chemicals.
Algaedyn comes in a handy 3-pack and the 1-quart bottle will treat a 20,000-gallon pool.
Pros
- High quality
- Contains silver that is higly effective at killing and preventing the growth of even the most deeply rooted algae cells
- Specially formulated for black and mustard algae
- Odorless and non-foaming
- Fast acting
- Safe for all pool types
- Helps to prevent algae accumulation in the filter
- Improves the effectiveness of chlorine
- Available in a 3-pack
Cons
- May need to be used with other chemicals for large black algae infestations
5. Eclipse3 Pool Algae Control System

For a natural approach to algae elimination and pH clarification, the Eclipse3 Pool Algae Control System is an excellent choice for any pool owner.
Eclipse3 is an all-natural mineral granular treatment that contains clarifying agents and natural pH balancers that are specially designed for pools, spas, and hot tubs. It contains a proven formula that is very effective in 3 areas: it eliminates algae growth, reduces your use of chlorine, and clarifies and stabilizes the water while maintaining a proper pH level, which can reduce your electrical operating costs by as much as 66%.
To create a stunning pool, spa, or hot tub that has crystal clear water and is always ready to use, just add an initial dosage of 20-ounce per 10,000-gallons, and a weekly dosage of 1.25-ounce per 10,000-gallons.
Pros
- High quality
- Great value for money
- Affordable price
- Three-in-1 pool care system
- All-natural mineral algae granular treatment
- Contains clarifying agents and natural pH balancers
- Designed for pools, spas, and hot tubs
- Very effective at killing algae
- Eliminates algae growth
- Reduces the use of chlorine
- Clarifies and stabilizes the water while maintaining a proper pH level
- Economical: reduces electrical operating costs by as much as 66%
Cons
- Not ideal for killing black algae
6. Clorox Pool & Spa Xtra Blue Algaecide

For a simple and smart approach to controlling algae in your pool, the Clorox Pool & Spa Xtra Blue Algaecide is a strong, multifunctional All-in-One Algaecide that kills and prevents algae growth and will create a healthy pool with crystal clear water which is perfect for swimming all summer long.
The non-foaming, extra-strong 40-ounce Clorox algaecide solution contains 3.3% copper and other stabilizing agents which effectively kills green, mustard, and black pool algae in just 24 hours and it can be used to treat large 25,000-gallon pools and also spas and it has a non-staining formula.
The Xtra Blue Advantage range features a wealth of multi-functional pool maintenance and algaecide products.
Pros
- Very good quality
- Very good value for money
- All-in-one algae killer
- Quick and effectively kills green, mustard and black pool algae
- Treats up to large 25,000-gallon pools
- Can be used for all pool types and spas
- Non-staining and non-foaming
- Fast-acting in 24 hours
- Creates crystal clear water
- Kills bacteria
- Protected against sunlight to last longer
- Large Xtra Blue Advantage range
Cons
- Expensive
- May take longer to work and needs to be applied more frequently to larger algae infestations
- Can make the water cloudy
7. SeaKlear Yellow Klear Algae Control

Take control of algae in your swimming pool with the SeaKlear Yellow Klear Algae Control.
The SeaKlear algaecide is an excellent algae fighter and is designed to control and prevent algae growth and to maintain clear water in chlorine swimming pools. It contains a 99% sodium bromide formula which is the highest amount in the industry which makes it an effective algae treatment for removing visible yellow and green algae accumulations in your pool.
For extra effectiveness for stubborn algae, brush the areas around your pool that are affected by algae accumulations. Add 4-ounce of the granules per 10,000-gallons of pool water, close to the affected areas, and for severe accumulations, add 8-ounce per 10,000-gallons of water.
The algaecide is EPA-registered and contains no metals and it is fast dissolving with minimum impact on pH levels. It leaves no stains or residue and is compatible with chlorine, bromine, and ozone sanitizers.
Pros
- Great quality
- Very effective against yellow and green algae
- Controls and prevents algae growth and bacteria and maintains clear water in swimming pools
- Strong sodium bromide formula
- Simple and easy to use
- Fast dissolving with minimum impact on pH
- Leaves no residue or staining
- May be used in all types of pools
- EPA registered
- Contains no metals
- Compatible with chlorine, bromine and ozone sanitizers
Cons
- Requires some additional applications such as brushing the algae off pool surfaces and adding chlorine
8. API Pond Algaefix Algae Control

To keep your ornamental pond, fountain or water garden, or indoor fish tank sparkling clean, the API Pond Algaefix Algae Control is a complete algaecide treatment for killing and controlling a wide range of algae.
The API Pond algaecide contains poly (oxyethylene dimethylamino) ethylene dichloride as its active ingredient and it is very effective at eliminating green water algae, string and hair algae, blanketweed algae, and other types of algae so that your pond or water feature has clean and clear and healthy water which allows fish and aquatic plant life to flourish.
You can safely use the algaecide for ponds that have Koi fish, pond plants, surrounding wildlife when used as directed. If you have fish, PondCare states that you should test a small amount to see how your fish react and before you use the algaecide make sure that the pond has vigorous aeration, such as a fountain, waterfall, or aeration device to avoid fish loss due to low oxygen levels. Also, if you are using PondCare Algaefix during warm weather and high water temperatures, 24-hour aeration is required before application, and make sure that you do not shut off pond pumps and aeration devices at night.
The 32-ounce algaecide not only controls existing algae problems but also helps to resolve future algae outbreaks and the product needs to be used every 3 days until the algae infestation is controlled and then treat your pond or water garden weekly.
The API Pond algaecide is available in different bottle sizes.
Pros
- High quality
- Very effective
- Fast acting
- Inexpensive
- Eliminates green water algae, string and hair algae, blanketweed algae and other types of algae
- Keeps pond water clean and clear
- Ideal for ornamental ponds and water gardens, fountains, waterfalls, indoor fish tanks
- Use as directed to keep water safe for fish, pond plants, and surrounding wildlife
- Controls existing algae and helps resolve additional algae blooms
- Available in different bottle sizes
Cons
- Works slowly with larger algae infestation
- Fishponds need to have vigorous aeration
- 24-hour aeration is required before application in warm weather and higher water temperatures
- For Koi fish ponds, it is recommended to only apply the product to small sections of the pond at a time
9. EasyCare FounTec Algaecide and Clarifier

To keep your water garden or fountain free of green algae and stinging mosquitoes, the powerful EasyCare FounTec Algaecide and Clarifier is an excellent product and it comes at a very affordable price.
A superior algaecide, EasyCare Fountec kills all types of algae such as blue, blue-green, yellow, and black algae and prevents regrowth in outdoor and indoor decorative fountains, water gardens (without fish), tabletop fountains, and birdbaths, and is safe to use around birds, plants, animals, but it is not to be used in ponds or water-gardens or tabletop fountains that have fish.
The non-staining, non-foaming algaecide formula contains Fountec’s special organic polymers that also super-clarify water which is an excellent deterrent for mosquitoes, flies, and wasps.
Fountec is very economical and long-lasting and you only have to use a small weekly application, just 1 drop per gallon or 1 tsp per 100-gallons. Once the algaecide absorbs into the algae and bacteria cell walls it will last a week or more. The result is sparkling clean water with no algae or insects.
Easycare is EPA registered and is non-hazardous, is safe to use around children and pets, and is safe for birds and plants.
Pros
- Excellent quality
- Highly effective
- Great price
- Clears pond and fountain water
- Kills blue, blue-green, yellow, and black algae types
- Can be used for outdoor and indoor decorative fountains, water gardens (without fish), tabletop fountains, and birdbaths
- Excellent deterrent for mosquitoes, flies, and wasps
- EPA registered
- Safe for all types of surfaces
- Non-hazardous, non-foaming and non-staining
- Does not require regular chlorine usage
- Kills and prevents algae better than other products
- Long-lasting
- Safe to use around plants, birds, and wildlife
Cons
- Not to be used in fish ponds
10. Pool RX Algaecide Blue Treats

The Pool RX Algaecide Blue Treats unit is an excellent choice as it simplifies pool and spa care.
Pool RX contains a proprietary blend of minerals with copper sulfate as its prime active ingredient and the unit continuously and effectively eliminates algae and reduces chemical demand and improves water quality so that your pool is free from all types of algae for up to 6 months.
The unit is very easy to use: just clean your filter, brush off algae, drop the Pool RX unit into the pump basket or skimmer, and the specially treated alloy cylinder that contains the special mineral formulation immediately dissolves out of the cylinder and spreads throughout the pool water. The minerals eliminate the algae while allowing chlorine to be more active and productive in the water. The unit makes use of the pool’s normal filtration process as the minerals are rejuvenated every time they pass through the cylinder.
The Pool RX algaecide unit can be used for all types of pools from 7,500-20,000-gallons, spas, and even saltwater pools.
Pros
- Great value for money
- High quality
- Contains a special blend mineral formulation
- Continuously and effectively eliminates all types of algae
- Can be used for 7,500-20,000-gallon pools, spas, and saltwater pools
- Effective up to 6 months
- Can be placed in the pump basket or skimmer basket
- Works with a pool’s normal filtration system
- Eliminates all types of algae
- Reduces chemicals usage
- Simplifies pool and spa maintenance
Cons
- Contains high levels of copper
- Need to brush off algae first
- Takes about a week to work depending on the size of your pool
Our Top Pick for the Best Algaecide

Our top pick for the best algaecide is the Kem-Tek Pool and Spa 1-quart Algaecide. Eliminate stubborn algae from your pool and spa with the highly effective Kem-Tek Pool and Spa algaecide. With a highly concentrated formula, Kem-Tek is the perfect choice for any pool or spa owner as the algaecide has a triple action modus operandi; it treats existing algae and prevents any new spore growth, and clarifies the water so that you can use your pool and spa all year round.
Check the price on Amazon