Algaecide - Further Reading

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While it’s hard to think about swimming in chemicals, diving into green and cloudy water is not so attractive either.

If you want to enjoy a crystal clear blue pool, you’re going to need to use a variety of pool chemicals to keep it clean. When many people spot algae growth in their pool, they will quickly turn to algaecide to clear it out. Not so quick though. Using algaecide in pool water to deter algae growth actually requires a bit more research.

Continue reading for Trouble Free Pool’s recommendations regarding the use of algaecide in your pool.

What are Algaecides?

Algaecides are a chemical that may inhibit algae growth in pool water.

Unfortunately, using algaecide in safe doses will not clear an algae problem once it's already appeared in your pool water. It is also important to note that algaecides do not actually sanitize pool water either.

In general, Trouble Free Pool does not recommend using algaecide for regular pool care. As long as you maintain the proper FC/CYA ratio in your pool, algae will not take over.

Concerns Regarding the Use of Algaecide in Pool Water

Using algaecides regularly masks the fact that the pool water is not safe to swim. Chlorine already serves as both an algaecide and a sanitizer. If you get algae in your pool it signifies that your chlorine level is too low thus algae is able to grow faster than the chlorine can kill it. That also means that the level is too low for swimming as well. No amount of algaecide will make the water safe even if it keeps the water crystal clear. This is the fundamental reason we don't recommend regular algaecide use during the swimming season.[1]

Instead, algaecide should be used as a preventive treatment either when closing up for winter or during specific processes such as Ascorbic Acid treatments when the FC level must be low already.

Be Cautious of Algaecides Containing Chemicals or Metals

Many algaecides sold at pool stores contain copper and you definitely do not want that accumulating in your pool water. Having copper in your pool water can stain your pools surface and also turn blonde hair green. Unfortunately, the only way to remove copper from pool water is by completely draining the pool.

If you choose to use an algaecide, it’s smart to know what all the chemicals are in it and what their effects will be on your pool water. If you are not sure, you can always ask on the Trouble Free Pool Forum before adding them to your pool.

Algaecides That Are Not Recommended

There are a few brands on the market that pose as an algaecide but are actually far from it.

Aquabrite Yellow Quell is sodium bromide that will convert your swimming pool from a chlorine pool to a bromine pool. Unfortunately, the only way to fix that is to drain almost the entirety of the water from your pool.[2]

Labels can be misleading. In fact, bromide is also NOT an algaecide, no matter what the bottle may say. The presence of bromide in water has been shown to not be effective whatsoever in the fight against algae.

Polyquat 60: Trusted for Use as Algaecide in Pool Water

If you are winterizing a pool when the water temperature is above 60°F, using an algaecide with Polyquat 60 may prevent algae and a green pool when pool season is back in full swing.

What is Polyquat 60?

Polyquat 60 is short for Polyoxyethylene (dimethylamino) Ethylene (dimethylamino) ethylene dichloride[3] 60% and is a quaternary ammonium cationic polymer.[4]. It is a type of chemical algaecide used to prevent algae growth. Many manufacturers bottle this to market for pool cleaning. It’s important when shopping around to look for pure Polyquat 60 such as from the brand ProTeam.

Some Considerations to Keep in Mind When Using Polyquat 60

  • Some Chlorine will oxidize Polyquat 60.
  • Polyquat 60 is a mild clarifier. The polyquat turns into a clarifier when broken down.[5]
  • This is the same sanitizer used in the Opti-Free contact lens solution so the chemical is safe for eyes as well.[6]
  • Polyquat 30 is a lower concentration of Polyquat.

Polyquat is very shelf stable and so it is not prone to degrading if it is sitting for a long period of time.

It is important to follow the instructions for use that are found on the bottle for proper circulation of the water.

Who Makes Polyquat 60?

Buckman Laboratories, in Memphis, Tennesee, manufactures all the Polyquat sold in the US, regardless of the label. Brands such as Arch (HTH), BioLab (Bioguard, Omni, Pool Time, Aqua-Chem, Sun, and many others), LaPorte (Robarb, etc.) are all simply repackaged (and possibly diluted) forms of the product that Buckman Labs produces.[7]

How To Use Polyquat 60

The following is Buckman Labs’ recommendation on how to use Polyquat 60 for closing your pool for the season.[8]

As they recommend for proper winterization, the pool should be "shocked" with about 5-10ppm chlorine to destroy any lingering oxidant demand and remove any residual ammonia or chloramine, etc. After a couple of days, adjust the pH back to 7.2-7.6 and add Polyquat 60 at the maximum rate as instructed per the label. This approach allows you to receive the highest benefit from both chemicals.

Another point that they make regarding using this algaecide in pool water is that after the addition of Polyquat 60, it’s important to keep the circulation pump on for at least 24 hours to make sure that the algaecide is thoroughly distributed throughout the pool.

If you raise your water to SLAM FC level then you should let the FC drift down before adding Polyquat 60. Having a moderately higher level (½ SLAM level so the FC/CYA ratio of 20%) is okay as well. The idea is that the Polyquat should last through the winter even if the chlorine does not.[9]

Buckman Labs says that even if the Polyquat is broken down, it is still effective when used as an algaecide. Moderate to high levels of chlorine break down Polyquat but it still only transforms the formula into shorter chain polymers that are still just as effective.[10]

The Advantages of Using Polyquat 60 During Winterization

If you close the pool when the water temperature is cold (50ºF or below), then the algaecide will last for a much longer time even in the presence of chlorine. That's why this is the recommended approach.

Basically in warm pool temperatures, after a week the Polyquat might degrade by about a third with normal chlorine levels. Meanwhile, if the pool temperature is closer to 50ºF, it would take perhaps 5-7 weeks for that same level of degradation to occur. That being said, even if you close your pool late and open early, there may still be some leftover residual of the algaecide and even the chlorine when you open in spring.[11]

Polyquat has been shown to last longer than chlorine, especially in sunlight. The main advantage of using Polyquat when winterizing is that in a pool exposed to any sunlight, the Polyquat will still last, especially if the water is cold. This helps to prevent algae growth even if the chlorine level lowers to 0. If you cover a pool and close it when cold, then chlorine will last longer as well.[12]

How To Use Polyquat 60 in Ascorbic Acid Treatments

Polyquat 60 needs to be added weekly throughout the whole time that you have the chlorine levels below normal (or at zero during the ascorbic acid treatment). It does not last forever and is not to be used as a one-time dose unless you only have the chlorine below or at zero for less than a week.[13]

It is also important to note that you should not mix the commonly used, "Jack's Magic Magenta Stuff" pool cleaner formula and Polyquat in a pool. According to the Material Safety Data Sheet (MSDS), Jack's Magenta Stuff is an acrylic acid copolymer. That means that it is a negatively charged polymer designed to attract and then bind to positively charged metal ions. On the other hand, Polyquat is a positively charged polymer. When you mix these two, you may form a cloudy mess in your pool water. Due to this, Trouble Free Pool recommends that you should never, mix these two.[14]

How To Be Effective in Your Fight Against Pool Algae

Pool agae.jpg

It’s no fun to finally open your pool for the season only to discover that it is filled with disgusting green algae.

Due to misleading labels and information on the market, it can be difficult to know what to do and how to handle it. As we have reviewed, Trouble Free Pool only recommends using an algaecide in pool water that contains Polyquat 60 during the winterization process for an effective, preventative solution.