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Backyard pools are a great place to exercise, relax, and have fun with family and friends. However, algae can get in the way of that fun. Some types of algae are simply an annoyance, while others can cause rashes, illness, or even worse.
If algae is a problem in your pool, algaecides are among the best algae removers for pools. They can kill algae, and some types also can prevent algae growth. To help maintain proper water balance and safety, an algaecide is typically used alongside pool shock treatments, chlorine, and other pool chemicals.
Pool algaecides can break up, suspend, and kill different types of algae to keep pool water clean and usable. The best pool algaecide helps keep your pool clean and ready for a quick swim. However, the pool type, the type of algae that’s present, and the other chemicals and products that are used in the pool all help determine the type of algaecide that works best.
Keep reading to find out what to consider when choosing the best pool algaecide, and check out some of the top options on the market for pool maintenance.
- BEST OVERALL: Kem-Tek Pool and Spa Algaecide
- BEST BANG FOR THE BUCK: Aqua Clear Pool Products Pool Algaecide
- BEST FOR SALTWATER POOLS: HTH Advanced Algae Guard
- BEST LONG-LASTING: Pool RX 6-Month Algaecide
- BEST FOR PREVENTING GROWTH: SeaKlear 90-Day Algae Prevention & Remover
- BEST FOR BLACK ALGAE: Applied Biochemists Black Algaetrine
- BEST NONFOAMING: In The Swim Super Pool Algaecide
- BEST IMMEDIATE SWIMMING: McGrayel Algatec Super Algaecide
- BEST FOR ABOVE-GROUND POOLS: Rx Clear 7% Copper Algaecide
How We Chose the Best Pool Algaecide
We researched the different types of algaecides and each type of algae it targets. We also considered ease of treatment, frequency of retreatment, and price. Other criteria included the concentration of the algaecide, the ratio of algaecide to gallons per water per treatment, and the frequency of the required treatments.
Above all, an algaecide must kill or prevent the targeted algae. While effectiveness is the biggest consideration, nonfoaming, nonstaining, pool-safe, and swim-safeness are also qualities important to this list of final picks.
Our Top Picks
The best algae killers for pools last several months and even eliminate tough black algae. The characteristics of the pool help determine the correct type, and the best algaecide proves itself over time.
Best Overall
Kem-Tek Pool and Spa Algaecide
Kem-Tek algaecide, one of the best algae removers for pools, contains polyquaternium (polyquat), which is effective on most types of algae, making it a good all-purpose product. The polyquaternium polymers attach to negatively charged algae cells, effectively smothering the algae before it can grow and spread. This slow dispersion is effective not only at killing algae, but also in preventing its regrowth. Polyquat pool algaecides don’t foam or stain.
This algaecide’s high 60 percent concentration typically eradicates algae quickly. High concentration also means the algaecide disperses slower, making it last longer. However, a broad-spectrum algaecide doesn’t target any one specific type of algae, so persistent blooms of a particular type may not respond. Kem-Tek Algaecide works for freshwater or saltwater pools.
Product Specs
- Compatibility: All types of pools
- Nonfoaming: Yes
- Targeted algae: Green, black, and mustard
Pros
- High concentration of polyquat; also helps clarify cloudy water
- Disperses slowly for longer-lasting effects
- Nonfoaming and nonstaining formula; suitable for most pool types
Cons
- May not work on persistent specific algae blooms
Get the Kem-Tek pool and spa algaecide at Amazon, Walmart, or Leslie’s.
Best Bang For the Buck
Aqua Clear Pool Products Pool Algaecide
Aqua Clear Pool Products pool algaecide targets persistent green algae with quaternary ammonium compounds. It’s designed for use with all pool types, including saltwater. The fast-acting formula includes dosing instructions that depend on the time it’s used in the cleaning cycle. For example, at the beginning of the season, apply 8 ounces along the edges of the pool, weekly for maintenance, or a high 16-ounce dose to kill persistent green algae. As a quat algaecide, it can cause foaming if used in excess.
Product Specs
- Compatibility: All pool types
- Nonfoaming: No
- Targeted algae: Green
Pros
- Inexpensive compared to other pool algaecide options
- Includes dosing for different times and uses
- Specifically targets green algae blooms
Cons
- Can start to foam if used in excess
Get the Aqua Clear Pool Products pool algaecide at Amazon.
Best For Saltwater Pools
HTH Advanced Algae Guard
HTH Advanced Algae Guard attacks three of the big algae—green, black, and mustard. It’s compatible with all pools, including saltwater, and users can swim immediately after application. HTH contains ammonium compounds that break down the membrane of the algae, helping chlorine do the killing part. The solution stays in the water to stop new growth.
This product can be used as a weekly maintenance treatment to achieve best results. Add to pools every 3 to 5 days.
Product Specs
- Compatibility: All swimming pool types
- Nonfoaming: Yes
- Targeted algae: Green, black, and mustard
Pros
- Pool can be used immediately after treatment
- Targets the most common types of pool algae
- Nonfoaming formula can create crystal clear water
Cons
- Requires weekly treatments for best results
Get the HTH pool algaecide at Amazon, Lowe’s, Ace Hardware, The Home Depot, or Walmart.
Best Long-Lasting
Pool RX 6-Month Algaecide
Pool RX 6-month algaecide cleans the pool with fewer chemicals and reduces pool maintenance. Each unit treats 20,000 to 30,000 gallons and lasts up to 6 months, staying in the pool pump or skimmer basket for constant release. Surrounding vegetation or rainfall may reduce the time that each treatment lasts.
The treatment kills algae with a copper compound. Copper is a highly effective algaecide, but it can discolor pool linings. However, this formula is designed to prevent discoloration. It’s compatible with salt systems, ozone, chlorine, and UV.
Users must purchase the right treatment for their pool size. Blue treatments are for pools that hold under 20,000 gallons of water, while black is for those with more than 20,000 gallons.
Product Specs
- Compatibility: Chlorine, ozone, UV, and salt pool systems
- Nonfoaming: Yes
- Targeted algae: All types
Pros
- Easy to apply; can last up to 6 months
- Copper compounds don’t discolor the pool
- Compatible with chlorine, UV, ozone, and salt systems
Cons
- Expensive and may not last a full 6 months
Get the Pool RX pool algaecide at Amazon or NewEgg.
Best For Preventing Growth
SeaKlear 90-Day Algae Prevention & Remover
SeaKlear 90-Day Algae Prevention & Remover contains copper salts that effectively eliminate algae and create an environment that prevents algae from coming back. This formula kills and prevents the four main types of algae—black, green, blue-green, and yellow (mustard). However, the pool water must be balanced for the algaecide to work.
Each treatment lasts 9 months with a 90-day algae-free guarantee. Users can increase the concentration of the algaecide to treat more severe outbreaks. A single treatment is 16 ounces, which is half a bottle. Severe outbreaks require an entire bottle, which can make treatment expensive if algae persists. Even though it contains copper, the manufacturers claim it won’t foam or stain.
Product Specs
- Compatibility: Unspecified
- Nonfoaming: Yes
- Targeted algae: Blue, blue-green, black, yellow
Pros
- Prevents algae for up to 90 days
- Attacks the most common forms of algae
- Nonfoaming and nonstaining formula
Cons
- Severe outbreaks require an entire bottle
Get the SeaKlear pool algaecide at Amazon or Walmart.
Best For Black Algae
Applied Biochemists Black Algaetrine
Thanks to a copper complex that’s designed for hard-to-kill algae, Applied Biochemists Black Algaetrine is the best algaecide for black algae. This algaecide coats and penetrates to prevent new growth in all pool types. As with other solutions, the water’s pH must be balanced for best results.
For it to work correctly, users must follow the directions exactly, adhering to the manufacturer’s recommendations as to timing and concentration. Applied Biochemists algaecide works alongside shock treatments, chlorine, and other maintenance products; no waiting period is required after treatment.
Product Specs
- Compatibility: Bromine, chlorine, and ozone pool systems
- Nonfoaming: No
- Targeted algae: Black
Pros
- Designed specifically to tackle tough black algae
- Users can swim immediately after treatment
- Works with all common pool types
Cons
- Must follow instructions exactly to avoid adverse effects and staining
Get the Applied Biochemists pool algaecide at Amazon or Pool Geek.
Best Non-Foaming
In The Swim Super Pool Algaecide
In The Swim Super Algaecide contains copper complex and chelated copper. It comes in a highly concentrated solution that requires only 4 ounces per 10,000 gallons of water. After the first treatment, it takes only 2 ounces per week to maintain the same 10,000 gallons.
As with other products, make sure that the filtration and water balance are ideal before using the algaecide, and follow the directions carefully. For example, the solution must be diluted prior to adding it to the pool. Some users report that this algaecide causes some discoloration.
Product Specs
- Compatibility: Inground or above-ground pools
- Nonfoaming: Yes
- Targeted algae: Mustard
Pros
- Fast-acting formula does not foam like some other products
- Concentrated formula works effectively and saves money
- Users can often see near-immediate results after treatment
Cons
- Requires following instructions closely to prevent discoloration
Get the In The Swim pool algaecide at Amazon, Leslie’s, Walmart, or In The Swim.
Best Immediate Swimming
McGrayel Algatec Super Algaecide
The McGrayel Algatec super algaecide kills green, yellow, and black algae, and the pool is ready for swimming right after use. The solution contains biostatic inhibitors that prevent algae regrowth, and it generally takes 8 to 24 hours to kill yellow and green algae and 7 to 10 days for more resistant algae like black. It can be used in freshwater or saltwater pools and doesn’t foam or stain.
The McGrayel algaecide works with or without chlorine, but it enhances the effectiveness of chlorine when present. However, it’s more effective when the pH levels of the water are balanced with appropriate chlorine levels. However, since a lot of the solution is required for each use, a bottle might not last long.
Product Specs
- Compatibility: All pool types
- Nonfoaming: Yes
- Targeted algae: Green, yellow, black
Pros
- Works with or without chlorine; suitable for all pool types
- Can use pool immediately after treatment
- Nonfoaming and nonstaining formula is easy to use
Cons
- Requires a large amount of solution to work; can become pricey
Get the McGrayel pool algaecide at Amazon.
Best For Aboveground Pools
Rx Clear 7% Copper Algaecide
Designed for use in all pool types, including above-ground pools, the Rx Clear algaecide doesn’t foam and successfully attacks a range of algae, including black, mustard, and more. Plus, swimmers can jump into the water right after treatment.
Rx Clear is highly concentrated, so each treatment requires only 4 ounces per 10,000 gallons. The algaecides disperse and coat the pool walls, keeping algae in suspension so they don’t grow and bloom. Users must retreat every 2 weeks.
Product Specs
- Compatibility: All types of pool
- Nonfoaming: Yes
- Targeted algae: Black, green, mustard
Pros
- High concentration reduces cost: only 4 ounces per 10,000 gallons needed
- Great versatility and works in all pool types
- Nonfoaming formula; can use pool immediately after use
Cons
- Comes in 1-quart bottle only; multiple bottles may be needed to cover the pool season
Get the Rx Clear pool algaecide at Amazon or PoolSupplies.com.
Jump to Our Top Picks
What to Consider When Choosing a Pool Algaecide
Algaecides are not all the same. Their ingredients target different kinds of algae, and some may target certain types of pools. Moreover, the algaecide’s concentration level and the length of time that the algaecide lasts can affect the pool maintenance budget.
Types of Algae
For those pools with one type of algae, choose an algaecide that targets that specific problem. However, several types of algae can grow in a pool, necessitating an algaecide that targets a broader range.
Algaecides work by making the algae more susceptible to the effects of chlorine. Green, mustard or yellow, and black are the most common types of algae, though they can appear in a broad spectrum of similar colors and types. Of all the types, green is the easiest to prevent and control. Black and yellow, on the other hand, are more pervasive because they resist chlorine.
The best black algae killer for pools usually is not an all-purpose algaecide; instead, use an algaecide made with copper complexes and chelated copper. These formulas also are typically the best algaecide for mustard algae; however, the copper can discolor the pool, hair, or clothing.
For algaecides that contain any form of copper as its active ingredient, look for one that also strives to reduce or eliminate discoloration. Typically, if the pool’s water is balanced and appropriately chlorinated, discoloration is less likely.
Long Lasting
A typical algaecide may require weekly or biweekly treatments, which means pool maintenance can get expensive. Long-lasting algaecides can cut down on overall maintenance efforts and costs, though they may cost more up front. These algaecides can last anywhere from 90 days to 6 months. Long-lasting algaecides have a slower dispersion rate, so each treatment lasts longer. However, many factors also affect how long it lasts.
Everything from rainfall to surrounding vegetation and the status of the filtration system help determine how long the algaecide treatment lasts. The cleaner and more balanced the water, the longer the algaecide stays effective.
Nonstaining and Nonfoaming
The three broad categories of algaecides are: quaternary ammonium compounds (“quats”), polyquats, and copper salts.
- Quats are a surfactant that changes water tension and causes the algae cell walls to split, so chlorine can kill them. Surfactants are commonly used in soaps and shampoos. If the pool contains too much quat algaecide, it creates a foam, similar to the suds when washing hair.
- Polyquats are similar to quats, except they don’t foam. They’re effective on green algae and the more resistant black and yellow algae, but they’re also more expensive.
- Copper salts, or “metals,” as they’re sometimes called, contain copper compounds, complexes, and chelates. Copper is an excellent algaecide; however, some copper salts products can cause staining, which, over time, can change the color of clothing, hair, and the pool. Looks for a solution that’s designed to prevent discoloration.
The pool’s pH balance and filtration must be at peak efficiency to ensure the algaecide works correctly.
Pool and Swim Safe
Some algaecides require a waiting time of as little as 15 minutes to a few hours before people can use the pool. However, swim-safe options are available that don’t require waiting.
Pool-safe algaecides work with any pool setup: freshwater, saltwater, vinyl above-ground, or concrete in-ground pools. To keep both swimmers and the pool safe, look for an algaecide that’s designed for the specific type of pool and water.
Tips for Protecting Your Pool Against Algae
Algae can be a persistent problem; however, you can stay ahead of it. But algaecide is just one factor in algae control. The best way to keep algae from starting is to maintain the pool regularly.
- Test the pool water weekly. Test and balance the pool water to keep it in the 7.2-to-7.8 pH range.
- Check and maintain the filtration system. Water circulation and filtration are very important. When testing pool water, also check the filtration. Algaecides must circulate throughout the pool to fully coat pool surfaces and tackle all the algae.
- Brush the pool. Algae can start on any surface in the pool. Regularly brush the pool’s bottom, sides, and steps to loosen any algae beginning to grow.
- Perform a weekly shock treatment. Shock treatments reinvigorate the chlorine in the pool and help clear the water. They can alter the chlorine levels for a short while, so wait until the chlorine level stabilizes before adding an algaecide.
- Maintain a regular algaecide treatment schedule. Follow a regular schedule for algaecide treatments. Some algaecides require a weekly treatment, while others may need it only every other week or even longer.
- Keep an eye on everything that enters the pool. Algae can get into the pool through debris or clothing. If swimmers, clothing items, and accessories previously have been in a natural body of water, wash them before they enter the pool.
FAQs
Picking an algaecide can be confusing, and it may take some trial and error to find one that works for your pool. Below are answers to a few common questions to help when selecting a product.
Q. Can I put too much algaecide in my pool?
Yes, you can. Too much algaecide can cause foaming or discolor clothing or the pool’s surfaces. Follow the manufacturer’s instructions for correct dosages.
Q. Does algaecide affect chlorine?
Algaecides can affect chlorine, though not all do. Algaecides actually help existing chlorine to more effectively penetrate the algae to kill it and prevent blooms.
Q. Can I use pool shock and algaecide together?
No. Even the best algaecide for pools can be neutralized by a shock treatment. Apply a shock treatment and wait for the chlorine levels to return to normal before adding algaecide.
Q. Can too much algaecide make a pool cloudy?
Yes, it can make it cloudy. Make sure to follow the directions on any algaecide to properly dilute it before adding it to the pool. Too much algaecide can not only irritate eyes and skin, but it can also actually work against efforts to control algae.
Q. How much algaecide should I put in my pool?
The amount of algaecide you use depends on the concentration of the solution and the size of the pool. Follow the manufacturer’s instructions carefully, measuring and diluting as directed.
Q. When should I add algaecide to my pool?
When it’s time for another algaecide treatment, add it after cleaning the pool. If added after a shock treatment, make sure the chlorine levels have returned to normal first.
