How to Blow Out Pool Lines for Winter

how to blow out pool lines for winter

Back when I had a pool service company, we had a few customers we saw only once per year. These were very hands-on, DIY clients who would have their pool completely closed, and called us out for our blow-only service to winterize the underground lines.

Blowing out the lines is not too complicated. Truly, anyone can do it with the right equipment.

The right equipment for the job, in this instance, is the Cyclone Pool Blower. A suitable substitute to purge pool lines would be the Mighty Vac 2-in-1 Blower and Vacuum.

Common Questions About Pool Plumbing Winterization:

Can You Blow Out Pool Lines Using an Air Compressor?

common questions about pool plumbing winterization

Yes, you could use a suitable compressor to blow out pool lines, but the potential exists to over-pressurize your pipes and fittings with a compressor. Compressors are high air pressure, low air flow. Cyclone pool line blowers, on the other hand, have low and consistent pressure, with a great deal more air volume. For more details, check out this video where Rox Cox explains How to Use an Air Compressor to Blow Out Pool Lines.

Can You Blow Out Pool Lines Using a Shop Vac?

Maybe. Large canister types of 5 HP or more should be able to handle the resistance of the water. Some wet/dry vacs will release excess air pressure under heavy resistance, but may still be able to blow out skimmers and return lines. The biggest problem is that most wet/dry vacs won’t blow out a main drain line. The same is true for many air compressors.

Can You Blow Out Pool Lines Using a Leaf Blower?

It seems logical that it could work. HOWEVER, I’ve tried it in a pinch with fairly powerful gas-powered leaf blowers. We had fun, used a LOT of duct tape, but had very little success. It may work for shallow skimmer and return lines after lowering the water level. But don’t expect great results for more demanding jobs.

The Best Solution?

The Cyclone Pool Line Blower will blow main drains without even having to lower the pool water level. You’ll have no problem with deep lines, small lines, or even large lines. Cyclone air blowers are also portable, as well as durable and easy to use. Did you know that Cyclone air blowers can also be used as a vacuum to set pool liners? Come to think of it, you could use the Cyclone to blow out lawn sprinkler systems, too!

So, let’s assume that we are using the Cyclone Pool Blower to blow out our pool plumbing lines, shall we?

Preparation To Blow Out the Pool Lines

  1. Lower the water level 4-12″ below skimmer, depending on your pool cover type.
  2. Remove filter, pump, and heater drain plugs to drain water. Replace loosely.
  3. Drain, hand pump, or scoop water out of the skimmer(s) until almost empty.
  4. Set the multiport valve to “Recirculate,” or to the “Filter” position for slide valves.

Next, Connect Your Cyclone to the Skimmer

cyclone

You’ll need to have two extra items, which I’ve neglected to mention until now. First, you need a small 3 or 6 ft. section of hose to connect to the Cyclone. And second, you’ll need an adapter to screw the hose securely into the bottom of the skimmer.

Most inground pool skimmers have two holes in the bottom when you look down into them. Usually the poolside hole is blocked off, and the deck-side hole is connected to the pipe. If both holes in the skimmer are open, then you have what most call a “combo skimmer.” In this case, the poolside hole in the bottom connects to the bottom drain of the pool, and the deck-side one is connected to the skimmer pipe. For combo skimmers, plug the main drain hole with a winter pool plug, and thread your hose adapter into the other hole that leads to the pump.

Thread the 1.5″ hose adapter into the bottom hole in your skimmer that connects to the pump. If your skimmer has 2″ holes in the bottom, you can use a plumbing adapter available at any home store, called a 2″ x 1.5″ threaded reducer. This PVC fitting is threaded on both sides, inside and out, to allow a standard hose adapter to fit a 2″ skimmer hole.

Attach a 1.5″ hose to the hose adapter, the other end to the Cyclone blower, and plug your blower into a grounded extension cord or directly into an outlet. You’re now ready to blow out your pool plumbing lines!

How To Blow Out Pool Lines

Blowing the pool lines is a 3-step process:

  1. Blow out the suction side.
  2. Next, blow out the equipment.
  3. Finally, blow out the pressure side.

1. Blow Out the Suction Side

The suction side is all of the incoming lines. Most pools have 1 or 2 skimmers and a main drain line on the suction side of the pump. These are the pipes that join together and come into the pump.

If you have a second skimmer, you can blow air from one skimmer to the other skimmer. In order to send the air through the other skimmer line, and without having to move the blower, there’s one more step. You will need to either close a valve off at the pump, or pull off the pump lid and plug the port coming into the pump.

If you have another hose, or a vacuum hose that you can connect to the other skimmer, this prevents reaching into the skimmer and plugging it while it’s spraying like a fountain. Blow air through the skimmer lines until just a mist is blowing out, or for about 2-3 minutes. Shown right is the PVC pipe rig that we thread in to blow water from secondary skimmer pipes.

Now for the main drain. Re-position your valves to blow air back through the main drain. With 3-way valves, loosen the knob so you can turn the handle past the stops. This blocks the entrance to the pump and will send water from the skimmer to the main drain.

When you see the massive plume of air rise up from the drains, allow it to blow for about 10 seconds and then close off a positively sealing valve (like a Jandy valve) on the main drain line. This will hold the water back with a column of air, much like a finger on the end of a straw.

If there are other suction lines, like a cleaner line or a spa drain, turn the valves again to send the air from the skimmer to each of these suction side pipes separately.

2. Blow Out the Equipment

Now we will blow air through the pump and through the filter valve. Remove the drain plugs on the pump and allow the air to push any remaining water out. Replace the drain plugs loosely. If you have a heater, do the same with the drain plugs on both sides of the heater.

Filters are not normally blown through the tank. If you have a multiport valve, place the handle on “Recirculate.” If you have a slide valve or a cartridge filter, however, the air will have to go through the filter. Remove your filter drain plug if you haven’t already done so, then replace loosely if blowing air through the filter tank.

You can leave filter cartridges or Diatomaceous Earth (D.E.) filter grids inside the tank if you are blowing air through the tank. But for safety, please open the air bleeder valve and ensure the tank clamp band is tight and secure before the blower pressurizes the filter tank.

3. Blow out the Pressure Side

Now that the air from the skimmer has blown through the pump, filter, and heater, we can now send it back to the pool through the return lines.

The return lines closest to the pump will begin to blow first. After 2-3 minutes of blowing, plug the wall return that is bubbling the most, then plug the other return lines. Make a tight, positive seal with your pool plugs, turning the wingnut until no air bubbles appear.

If you have other pressure side lines, such as an automatic cleaner line or a spa return line, blow each of these out separately. When there is a spa blower on an attached spa, turn on the spa blower while you are blowing and plugging the spa jets. Blower lines often have a 2-way valve on the vertical PVC pipe. Close this valve while the blower is running, and then quickly shut off the blower.

Additional Steps

Water Feature Pumps

Waterfall and fountain pumps are usually blown out at the pump itself. The builder may have installed a tee fitting to connect a blower. If not, you can remove the pump lid and hold your blower hose while blowing air in both directions.

To do this, push the hose into the pipe that comes into the pump. This will blow air back towards the pool (provided there is no one-way check valve installed). Secondly, remove the pump basket and place the air hose into the volute or impeller housing. Make a good seal and turn on the blower. This will blow out the pressure side of your water feature.

Keep the blower running until just mist is blowing out. If lines are underwater, plug them while the blower is running. But for lines that are above water level, you can shut off the blower and then plug the pipe. Be sure to plug up any pipe outlets to keep out rain water or rising pool water levels.

In-Floor Cleaner Systems

If you have pop-up jets on the steps and floor of your pool, locate the head unit, aka water valve, and remove the clamp band to expose the 5 or 6 pipes that lead to the pop-up jets. Blow each pipe individually until you see bubbles in the pool, then plug it fast with an appropriate-sized winter pool plug, usually a #7 or #8. Wrap a plastic bag over the plate and pipes, and store the head valve indoors.


So there you have it! That’s how we blow out the lines for an inground swimming pool winterization!

With a Cyclone Pool Blower, you can stop paying hundreds of dollars each year for something you can easily do yourself. Once you start bragging about this to your neighbors, you (and your blower) may become very popular this time of year!

Here are 3 Pool Center videos on how to use the Mighty Vac (a predecessor to the Cyclone blower). These videos show exactly how to hook it up and blow out your own pool plumbing.

29 thoughts on “How to Blow Out Pool Lines for Winter

  1. john stamatov

    Great posts. However, I still have a question on blowing lines. I too just purchased a Cyclone. I have a Janey valve that is either in the main drain closed, or skimmer closed position, or somewhere in between. There are two skimmers. Can I still blow from the deep end skimmer back to the pump. I assume when doing this, I put the valve in the “close” position for the main drain (so if operating, the pump would be sucking from the skimmers only). Then plug the skimmers after blowing air for 5 min. Then move valve to to close the skimmers (so pump now would be sucking water through main drain only); but now I would have to move the Cyclone and push are back through main drain; OR do I not plug the skimmers and evacuate the main drain by continuing to blow through skimmers, but only moving the valve position from main drain off to the skimmer off/closed position. Want to make sure I sequence properly to get the proper air lock on the main drain. Many thanks (pS. I have a pentair that doesn’t have one of those fancy multi-port valves – it’s only a slide up or down gate valve to drain.

    • Hi John, If your main drain valve is installed on the pipe that leads into the pump, then you should be able to ‘deadhead’ the pump by loosening the valve handle lock nut, and raising the handle over the lid stops, so that you can close off the pipe going into the pump, and with one skimmer plugged, you can blow air from the other skimmer, directly past the pump, and into the main drain pipe. If that does not work, plug both skimmers, or deadhead the skimmer valve, and place the blower hose inside the pipe that comes into the pump (removing the pump lid), to force air back to the main drain. Allow the air to forcefully blow for about 20-30 secs, and then quickly close the main drain valve, while the air is blowing.

  2. Rhonda Hypnarowski

    I am closing my pool for winter. This year I drained water level to an inch below skimmer frame which also fell below jets. I always use an air compressor to blow out the lines. In the past jets would bubble and I would then plug them up. This year very little water came out. Just dribbled. When blowing out main drain no bubbles came up from drain. It is an ungrounds pool. What am I doing wrong?

    • Hi Rhonda, losing pressure somewhere, is the drain on the compressor tank open? Is the pressure the same (on the tank) as always? Could be a leak out of the multiport valve or air bleeder on the filter, or a plug removed that you thought was in place. Somewhere, there is an air leak…

  3. Swim Pool Hero

    Great article, as a professional pool guy , I always also use the cyclone blower its a great machine.

    I can still remember doing pools 1991 before we had these, it was such a pain
    I have also seen the main drain tied into one of the skimmers.

    anyhow just wanted to stop by and say hello

  4. Hi, no antifreeze in the returns or main drain line. You can put some into the skimmer line, just in case. No need to do it for the returns, and for the drain, antifreeze is heavier than water, so it will flow out of the drain…

  5. Werner Johnson

    Hi. It looks like most of the application discussion is around winterizing. I am in Houston and not concerned with this; however, I tend to get my main drain clogged with debris due to nearby trees. I get the pool guy to come out and blow it out with CO2 every year but this is expensive. My question: is the Cyclone effective at blowing out debris (mostly leaves) from the main drain? I have a 6′ deep 22k gal in ground pool. Thanks, Werner

    • Hi Werner, Yes Cyclone would practically blow the leaves right out of the pool! Kidding, but yes can be used for pipe clogs, but I’m wondering if a new style drain cover may help? There are a few larger retrofit drain covers, like the DrainSafe VGB approved for safety that may keep out the leaves, Or placing the Polaris UniBridge over your drain, to keep it from clogging? You’d need to vacuum or scoop and brush the debris from the drain, or run a pool cleaner, but may prevent the clogging issue?

  6. Kevin Walsh

    Hi…great blog, thanks for the info. Apologies if this was covered somewhere, didn’t see it. First year closing my pool, is it hypercritical to get every last bit of water out of the suction/return sides? I used an air compressor and blew the return side out until bubble appeared for a minute or so, then capped. On the suction side, I blew back from the pool skimmer, towards the filter and secondary skimmer basket with a shop vac, and ran that until very little water was coming out…though there still was a trickle that never seemed to stop. Is it okay to have a trace amount of water in there, as long as there isn’t enough to build up pressure when freezing? Worth dumping some antifreeze in to be on the safe side? Live in the Northeast where it’s common to be below freezing for long stretches. Thanks in advance.

    • Hi Kevin, it’s not necessary to get every last drop. Sounds correct what you did, just blow the line for a few minutes, until just a mist or drips comes out. What is left inside, coating the pipes, will drip down to the lowest (underground) part of the pipe, where it is most protected from the cold. In addition, pipes won’t crack unless they are absolutely full of water, if water is only filling half of the pipe, when the water freezes and expands, it has room to expand inside the pipe, so that it won’t put pressure on the pipe walls. Rest easy this winter! 🙂

  7. Luis Carrasco

    Hi Dave,
    I just bought a Cyclone 3 HP Liner vacuum and pool line blower. This will let me blow the lines from the skimmer.
    Is the first step, should I close the valve that carries water to the filter or leave it in recirculation?
    With the cartridge filters should I remove them before blowing the return lines?
    Thank you

    • Hi Luis, if you have a filter bypass valve between your pump and cartridge filter (most people don’t, or if you have a filter with a multiport valve set to recirculate), then you can close off the filter, no need to blow air thru the filter, just remove the drain plug. If you do need to blow air thru the filter however, as most cartridge pool owners or filters with SLide valves would need to do, there is no need to remove the cartridges (or DE grids) when blowing air through the filter, the Cyclone blower is low pressure – high volume, so it won’t damage anything. Congrats on a great purchase! Let me know if you have other questions on using the Cyclone.

  8. Hi Davy,
    I have an equalizer line on one of skimmers that sits completely below the water line after draining the pool. What’s the best way to get the water out of it without it refilling? Same is kind of true for my vacuum line. The base of the opening sits about 1/4” below the water line.
    Thanks,
    Steve

    • Hi Steve, normally, one would plug it at the wall, on the inside of the pool, and then pump out the skimmer or drain the skimmer. For the vacuum line, you could blow air from the pump, back to the vacuum line, and plug it while it is bubbling. Be sure the wall plugs are deep into the pipe, so they will stay put, and not get pulled out by a moving ice sheet.

  9. Hi Davy, when I blow out the suction side, do I only need to close a skimmer of blower in valve off and open another skimmer valve and main drain valve? This is my first time to close my pool. Thank you very much!

    • Hi Ming, many times there is a way to blow all lines from one skimmer, by turning the suction side (skimmer/main drain) valves to direct the air from skimmer to skimmer, then skimmer to drain, and then skimmer into the pump/filter/heater and back to the pool. In some cases, the valve plumbing is arranged in such a way that a valve needs to be dead-headed, or turning the valve handle past the valve handle stops on the valve cover. This is done by loosening or removing the valve handle locking knob, so that the handle can be lifted above the valve stops and turned to a position to block off air going into the pump, or into another line. In other cases, it is easier or necessary to move the blower, from one skimmer to the other skimmer, blowing each skimmer individually, or – using the blower from the pump, blowing air backwards to the skimmer/skimmer/main drain. When both skimmers are on the same pipe, without separate valves, blow from skimmer to skimmer, and then plug the other skimmer tightly before proceeding to blow the drain, and thru the pump/filter. To get all the water out of the second skimmer, connect a hose adapter and a vacuum hose, and blow the line until only a mist blows out ( you can also make a ‘skimmer stick’ out of rigid PVC fittings and pipe, into an upside-down “L” shape. If you don’t have a hose adapter, have a helper hold the vac hose tightly over the second skimmer hole, until just a mist is blowing (usually 2-3 minutes).

  10. Rob Brewer

    I have 2 drains in the deep end. My plumbing only has 1 valve coming off the filter. There is also a safety device in the pool deck. I have 2 skimmers . 1 has only one pipe the other has 2. What procedure do I use to blow the lines out ?? I’m in Pa.

    • Hi Rob, after lowering the water level to winter level, put a plug firmly in the front hole on the deep end skimmer (pool side hole). Screw in a hose adapter to the back hole and connect a vacuum hose. Now set up a blower on the shallow skimmer, and blow out the line to the open pump (lid removed). Then dead-head the incoming valve (raise the handle to turn it backwards, to block air flow into the pump), or put a plug into the pipe coming into the pump, or place multiport valve on Closed position… blow air from shallow skimmer to the pump, and back out to the other skimmer. Remove hose and plug the other skimmer. Un dead-head the valve, and place multiport valve on Recirculate. Remove filter drain plug and both pump drain plugs. Blow air thru pump and filter, then replace the pump plugs loosely and blow air back to the pool returns. Plug the strongest blowing return first, then the other(s). Don’t forget to use an ice compensator in the skimmers, like a Gizzmo. Also good to put a piece of plastic under the skimmer cover, to keep rain out.

  11. Hi Davy,

    I noticed you mentioned on both types of skimmers (combo skimmers and old style Anthony skimmer with main drain) it is not necessary to blow the water out of these. Won’t the water in these pipes freeze and cause it to crack? Just curious because I am closing my pool with anthony old style skimmer this week ( I am in NJ) and am worried about the line cracking over the winter. Thanks so much. This is a great site.

    • Hi Alex, yes you are correct, and that’s because it’s hard to blow out a combination main drain/skimmer line, no matter the arrangement (side by side or upper/lower), and then get it plugged before the water rushes back into the pipe. In milder winter areas, possibly including NJ, just plugging the main drain line is sufficient. Being that it is so far underground, there is very little chance of freezing. However there are some methods, and depending on the pool, it would be smart to blow out the main drain line. On a side-by-side combo skimmer, where you can see two holes, the front one is usually the main drain line. Hold the blower hose firmly over the hole, and let the drain blow for 10-15 seconds. Then a helper can get one arm into the skimmer, and right as you release the hose, in goes the plug, tightened fast. Another method is when using an air compressor, use a specialized plug that has an air valve, tighten the plug, and then give it a blast of air, and then an air lock will hold out the water (like a finger on the end of a drinking straw). For top/bottom old style skimmers, there are double-plugs made, with two plugs mounted on a single rod. The lower plug is usually a #7 or #8, and the upper plug is a #9 usually. These are made specifically for top/bottom combo skimmers, where there is only one hole in the bottom of the skimmer. For this to work, the plug is inserted halfway down into the skimmer and held in place by one person, while the other person blows air (backwards) from the pump to the skimmer, when the drain starts bubbling, the double plug is pushed down to full depth, and tightened fully. Another way for top/bottom skimmers is if you have a positive sealing skimmer valve at the pump, like a Jandy valve, you can plug the skimmer with a #9 or #10 firmly, and then blow air back to the skimmer, from the pump, until the main drain blows forcefully, then close off the valve on the skimmer line, to make an air lock (like the finger on the end of a straw). Air locks don’t always work however, if the valve is leaky or the plug is leaky. There is a lot of water weight pushing against the air in the main drain pipe. Fortunately, main drain lines do not commonly break during winter, but they can and do in certain instances, but not normally on old style pools in NJ – built well with very deep pipes to protect against such things. (PS – pouring in antifreeze won’t work because it is heavier than water and will run out the drain. However there is an antifreeze trick of pouring in a cup or so of Pool Antifreeze, which causes the water in the main drain pipe to drop by 12-18″, just temporarily for a few seconds, and then it rebounds back up again. If you plug the main drain line very quickly after pouring antifreeze into the line, it can create an air lock, keeping the water level in the pipe, at that lower level. But the antifreeze won’t provide much protection, as it will run out the bottom drain, into the pool.

      • Alex Gambelunghe

        Davy,

        Thank you for such a details explanation. Your advice is excellent and covers lots of different scenarios. I lowered my water about 18 inches(as per specs from cover manufacturer) and there was still about 1/4 inch of water in my skimmer that the main drain is attached to. My other skimmer was completely empty. I pour about 1/2 gallon of anti freeze into the main drain pipe but couldn’t get the water to drop down like you mentioned. So I just put a plug in. Should I have lowered the water until it no longer filled the skimmer with the drain?

        • Hi Alex, You should be OK with what you have described. PS – make sure that only Pool Anti-freeze (non-toxic) is used, never use automotive anti-freeze. If you are blowing the lines, another way to winterize a side-by-side skimmer plumbing arrangement is to blow the drain line, and in one very-fast motion, remove the hose and plug it fast, before the water rebounds back up in the pipe. But in most cases, just plugging the drain line is fine, even before lowering the water, or if the skimmer is still full of water. Because it’s located so far below ground level, would only have concerns for very cold northern locations with prolonged freeze periods of weeks and weeks.

  12. Hello, great website and info. I had a question I have an older Anthony-Sylvan pool it has 1 skimmer a return, a Polaris pressure line and a main drain. If I blew out all my lines already including closing up my skimmer with a Gizzmo under air pressure and air-locked my main drain. If I removed the Gizzmo to add some anti-freeze to the skimmer line at this point, would it undo everything I already did and possibly let water into the other pipes I already plugged/air-locked? I usually add a little anti-freeze to the skimmer line but forgot this time. The skimmer line usually just takes about 2 cups of anti-freeze before filling into the skimmer and I did remove the standing water with a wet dry vac before and after blowing out the skimmer. Any advice or suggestions would be appreciated.

    • Hi Rich, if your (older) Anthony/Sylvan pool has the combination main drain, where the drain pipe connects into the skimmer pipe, and you winterized the skimmer and drain with an air lock by tightly plugging the skimmer and closing off a positive sealing valve like a jandy valve at the pump, then yes, removing the Gizmo to add antifreeze to the skimmer line will release the air lock. If your skimmer is like the image on the left, you can reach down and plug the Anthony main drain with a #8 extended plug to winterize. For the image on the right, you have to air lock from the pump, and hope for the best. If you have a side-by-side drain combo, you can just plug the drain line, usually the front hole, and blow the back hole to the pump.

  13. I LIVE IN NORTH CAROLINA AND MY POOL STORE SAID I DIDN’T NEED TO BLOW MY LINES OUT,BUT I AM CONCERNED ABOUT WHAT TO DO. I HAVE TWO SIDE JETS AND ONE BOTTOM SKIMMER AND ONE MAIN SKIMMER.

    • Hi Julie, as a general rule, for each day of below freezing temperatures, 32° or lower, the ground freezes about an inch. If you nearly never see freezing temperatures except at night, then you could be safe to lower the water below the returns, empty out the skimmer, and plug the skimmer and returns – and drain the pump, filter, heater, etc., then cover the pool. If your temperatures can stay below freezing for a few days in a row, add pool antifreeze to the skimmer pipe and return lines before plugging. If your temperatures could stay below freezing for many days in a row, then I would definitely blow out the skimmer, returns and main drain pipes, with something like the Cyclone blower. It’s easy to do, just connect to the skimmer, and you can blow out your drain (then close the MD valve while it’s bubbling), then blow thru the pump, filter and back out to the returns, and plug them while bubbling.

  14. […] How to Blow Out Pool Lines for Winter Winterize your In Ground Swimming Pool 10 Steps to Winterize Above Ground Swimming Pools […]

  15. You make mention of the combo skimmer above, but I am unclear how to blow out the main drain line. My combo skimmer, old Anthony pool, shows two threaded holes in the bottom. One leads back to the pump (suction) and one goes to the main drain. I can blow back from the skimmer to clear the suction line, but I am unclear as to how to clear the main drain from the skimmer since it will back fill when I remove the pressure. What is the manufacturers process to create an air lock on the main drain from a combo skimmer?

    • Hi generally, these lines are not blown out. In practice, you would simply plug the main drain hole, after lowering the water level. That”s how weve done it for years, without a problem (that I know of). If you really wanted to blow it out, you could use a test plug, the type with an air valve on top. Tighten up the rubber plug in the hole, and attach an air compressor hose to the air valve and in this manner, you can blow out the line, but it”s probably not necessary to do so.

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