How to Use Swimming Pool Antifreeze

Using pool anti-freeze to Winterize a Swimming Pool
by Rob Cox September 09, 2014

Using Swimming Pool Antifreeze



Swimming pool antifreeze, also called non-toxic antifreeze, is the same stuff that RV owners can use in their motor home water systems.

For swimming pool use, it can protect swimming pool pipes down to -40°, when added in correct proportion.

Here's some Q&A regarding the use of pool plumbing antifreeze.

Q: Is swimming pool antifreeze necessary? 
I'm sure that I've said it on this blog before, so I'll say it again - NO. Not if you blow out your plumbing lines correctly. That is, if there is no water in the pipes to freeze, then there's no need to use antifreeze. However, many folks like to use antifreeze as additional insurance against faulty plugs, or if you're not really certain that all of the water has been blown out.

Q: How much pool antifreeze is needed? 
A: Most manufacturers advise to use 1 gallon of pool antifreeze for every 10 feet of 1.5 inch pipe. This assumes that the pipe is full of water however. If you are adding it to an empty pipe (or nearly empty pipe), considerably less could be used. 

Q: How do I add pool antifreeze?
A: After lowering your pool water to the winter level, you can pour it into the skimmer to protect the skimmer line. If you want to use it in the return line, cleaner line or get it into the main drain line, you will need to use a section of garden hose with a funnel, so that you can insert the hose from the pump or from a partially disassembled valve. 

Q: Can I pour it into the pump, filter, heater, chlorinator? 
A: NO! Remove the drain plugs for your pool equipment, and better yet, some air to remove the water. Using antifreeze in your equipment can cause damage, as the salts and glycol will react with metals and rubbers. Antifreeze also reacts dangerously with chlorine, so be sure not to add it to a chlorinator. It will gum up a pool filter. I repeat, do not use antifreeze in your equipment. If your pump sits below water level and you have concerns, just leave the drain plugs out all winter, or remove the pump and store it indoors.

Q: Can I pour antifreeze directly into the pool? 
A: Some of you may be laughing at this question, but it's been asked many times. NO - the pool will freeze, and you would need a LOT of antifreeze to prevent it from freezing. Pool antifreeze is not for the pool, but for the pipes. For aboveground pools, you should use an air pillow to break up the ice sheet that forms in the pool, or you can use half a dozen milk jugs, filled partially with pebbles and pool antifreeze, to absorb the ice expansion.

Q: Will antifreeze protect a main drain line? 
A: Maybe, but keep in mind that antifreeze is heavier than water, and it will seek the lowest level in the pipe. If your main drain pipe has a steady pitch, as many do, you may notice the antifreeze coming out of the main drain, into the pool shortly after adding it.

Q: Will pool antifreeze harm the pool if it gets in the water? 
A: NO, it's specifically non-toxic and won't have any effect on the water chemistry and is not dangerous to swimmers. However, most people I know will that use antifreeze will start up the pump with the multiport valve on waste, to pump the antifreeze out of the backwash line. If you have a cartridge filter this may not be possible, so no worries, just let it mix with the pool water.

Q: Can I use Prestone, or other automotive antifreeze? 
A: NO! Ethylene Glycol is very toxic, and should never be used. Make sure the bottle is labeled Pool Antifreeze, which contains propylene glycol.

Q: Isn't there two types of pool antifreeze? 
A: There are - the most common is propylene glycol (the pink stuff). You can also find a calcium based antifreeze, which is usually colored green. But, I haven't seen that around in the last few years. It was touted as being safe to pour into the pump, and was also non-toxic to humans and pets.

Q: Will pool antifreeze harm my pets or wild animals? 
A: Non-toxic pool antifreeze should not harm animals, but if they drink it, it will likely cause an animal to become sick. Automotive antifreeze is definitely dangerous and can lead to kidney and liver problems, if not death.

Q: Should I pour Pool Antifreeze in the skimmers after plugging the hole? 
A:  NO, this makes a scummy mess come spring, and it can attack rubber plugs, or the o-ring for threaded skimmer plugs. The better solution is to fill a quart or gallon bottle with pea gravel and/or antifreeze, and drop it in the skimmer after plugging the hole. This 'skimmer bottle', as I call it, will absorb expansion when ice forms in the skimmer. Using a piece of heavy plastic under the skimmer lid can help keep rain water from dripping into the skimmer during winter.

Q: Are there any valid uses for Pool Anti-freeze? 
A: Sure, if you don't blow out the plumbing lines, or if you want some added insurance against a failed plug, antifreeze can be poured into the plumbing lines. It also can be used to make the skimmer bottles, as described above. 

Q: Can I make my own Pool Antifreeze? 
A: I have never heard of this being done, but ... if you had extremely salty water, it will definitely freeze at a lower temperature than regular water. Or, you could fill the pipes with grain alcohol - but that would just be a waste of good booze!

Q: Does Poolcenter sell Pool Antifreeze? 
A: I thought you'd never ask! We sell two types of Pool Anti-Freeze, both non-toxic propylene glycol blends, made specifically for pool winterization. The concentrated version, which makes 3 gallons, is a much better bargain, at only $3.33 per gallon. It's also much cheaper to ship than full gallon bottles.


- Rob