When Should I Use A Pool Algaecide?

So you walk into your backyard.  Yesterday your pool was clear.  Now it's green or cloudy.  You might think, "Oh, I'll just add my favorite pool algaecide and everything will be fine."  But before you pour it into your pool, we need to establish something:  Algaecides are used for preventative maintenance.  It's simply not equipped to actually kill algae.  It cannot kill algae spores faster than they can reproduce.

What Is A Pool Algaecide?

Algae in your pool can be an annoying issue.  Many things can contribute to green pool water such as water temperature, sun, heat, low sanitizer levels, and pH balance.  Pool algaecides are chemicals that have active ingredients to prevent algae from growing in your pool.  The most common pool algaecides:

• Contain either copper ions, copper sulfate, or chelated copper.
• Contain quaternary ammonium compounds (referred to as “quats”).
• Are polymeric quaternary ammonium compounds (referred to as “poly-quats”).

Different Types Of Pool Algaecide

If you've ever seen the rows and rows for pool water algaecides, you may have become overwhelmed.  It's really not that difficult to understand.  The 3 main types of algaecides are "metal" based, "poly" based, and "bromide" based.  While metal based pool algaecides (copper and silver) are the most popular, I recommend to never use them.  This is especially true if you have metals in your water.  All you're doing is adding more metal to your pool water and that's something you don't want to do.  And bromide based algaecides are not needed either.  The bromide must be converted in bromine to actually be used as an effective sanitizer.  The product most widely used for this conversion is chlorine.  Why not just skip the bromide based algaecide and go directly to chlorine?  Makes economical sense, right?

If you're going to use an algaecide, I recommend using what is known as a PolyQuat 60.  This kind of algaecide is safe for all pool surfaces and won't foam up like a metal based algaecide can.  Your best bet is to maintain your pool chemistry and keep your filter working at peak performance.  

How To Use A Pool Algaecide 

Adding a quality pool algaecide to your pool is fairly simple.  We always want to follow the directions on the bottle, but this quick list will get you going. 

• Make sure your pool water is balanced.
• If you need to, first shock your pool, then allow the chlorine level to decrease to an acceptable level.
• Add the algaecide according to the package directions.
• Let your pool sit overnight. 
• Adjust your pool's pH level and monitor the chlorine level.  

A PolyQuat 60 algaecide is the best on the market and will give you the desired results.  And as always, use a good pool test kit.  The test kit I've used since 1999 and highly recommend is the Taylor K-2006 kit.   

Prevention Is Key

Your pool can go green from time to time, but you usually don’t need a pool algaecide to get rid of it and clear it up.  Keeping your pool water chemistry balanced, adding chemicals when needed, along with a good clean filter, will prevent algae growth in most cases.

Pool Algaecide FAQ 

There are certainly a lot of questions about algaecides.  This list will hopefully clear up some of the confusion. 

What is the best pool algaecide?

The best algaecide is called PolyQuat 60 and can be either bought online or at your local pool store. 

Do I need algaecide in my pool?

Technically, no.  As long as you're able to maintain your pool chemistry, there should be no need to add an algaecide.  However, situations are different.  If your pool requires an algaecide, I suggest using one.

What do I do if I put too much algaecide in my pool?

There's no chemical to reduce an overdose of algaecide.  The fastest solution is a partial drain and refill.  Pool algaecides do break down over time and will get filtered and backwashed out. 

How long can you swim after adding algaecide?

You will want to wait about 30 minutes to an hour after adding your algaecide to resume your normal swimming activities.

How much algaecide do I add to my pool?

Always follow the directions on the bottle, but as a general rule of thumb, you will use 18 fl. oz. per 10,000 gallons of pool water for the initial dose and 6 fl. oz. per 10,000 gallons every 5-7 days.