Antifreeze in bottom drain lines for winter?

[Whynotme]

My pool builder (Kayak) says antifreeze is not recommended. Many people on this FB group who work on Kayaks say they use antifreeze. It does get cold where I live but I've never checked the pool to see if it's ever been frozen. Anyhow, if I just hang the bottom drain pipe up higher than the water level, the water will not flow out, so my question is this - will just leaving the drain pipe up high leave enough room for expansion should the water in that bottom drain line freeze? Or how many of you use antifreeze in your bottom drain lines? Thanks

 

[Newdude]

Got pics ? None of us have kayaks. Are they traditional main drains, or wall drains ? Rigid PVC or flex pipe ?

I'd want the openings plugged on the inside and the pipes emptied or removed. If they've been blown and there's no water in them, then antifreeze is only redundant insurance in case the pipes fill again.

Anyhow, if I just hang the bottom drain pipe up higher than the water level, the water will not flow out,

Correct. But the pipe may burst when it freezes. The opening area has room for ice expansion and it will mushroom out, but further back down the pipe doesn't.

 

[Whynotme]

 

[Whynotme]

Got pics ? None of us have kayaks. Are they traditional main drains, or wall drains ? Rigid PVC or flex pipe ?

I'd want the openings plugged on the inside and the pipes emptied or removed. If they've been blown and there's no water in them, then antifreeze is only redundant insurance in case the pipes fill again.


Correct. But the pipe may burst when it freezes. The opening area has room for ice expansion and it will mushroom out, but further back down the pipe doesn't.

Just posted a pic. Left pipe is skimmer. Middle is bottom drains. Right is return. Some say just raise the end of the bottom drain higher than the water level and if it freezes it has somewhere to expand. Others say use antifreeze in that pipe. I guess using antifreeze would be like insurance. I just worry that it could eventually make it's way into the pool itself through natural diffusion.

 

[Newdude]

Crud. That's what I was afraid of. Main drain lines on above ground pools are tricky. Mine are 4+ ft down at the edge of the pool and yours is inches. While you can raise the pipe to not expel water, any blowout down low will all but empty the pool.

Antifreeze with an open end will just glug glug into the pool.

I'd plug the drain from the inside then shop vac the line empty. You could probably get a garden hose all the way in there and then vac the garden hose. Then add Antifreeze if you want the insurance.

Plug the return and use a gizmo in the skimmer and manipulate them so they drain.

 

[JamesW]

Can you blow it out and airlock it?

 

[Newdude]

Can you blow it out and airlock it?

Not in a horizontal pipe with the drain side open. It'll glug itself full in seconds.

Do the finger on a straw trick but then turn it sideways. The water will push the air right out. In the middle of the pool it doesn't matter because 4 ft of water will insulate it and it won't freeze. But towards the side of the pool it is only a couple of inches deep and will freeze.

New Hampshire gets real winters.

 

[Whynotme]

Crud. That's what I was afraid of. Main drain lines on above ground pools are tricky. Mine are 4+ ft down at the edge of the pool and yours is inches. While you can raise the pipe to not expel water, any blowout down low will all but empty the pool.

Antifreeze with an open end will just glug glug into the pool.

I'd plug the drain from the inside then shop vac the line empty. You could probably get a garden hose all the way in there and then vac the garden hose. Then add Antifreeze if you want the insurance.

Plug the return and use a gizmo in the skimmer and manipulate them so they drain.

Exactly how do I plug a bottom drain from the inside? I'm surely not getting in 58° water.

 

[mas985]

Not in a horizontal pipe with the drain side open. It'll glug itself full in seconds.

After purging the line and while under pressure, if there was a 2-way valve in-line and it was shut off the pressure would prevent the water from rising in the pipe. The horizontal portion may or may not fill depending on the slope of the line. If the top of the pipe connection to the MD fitting is more than a few inches below the level surface of the ground, then it should only fill by a couple of inches which should not be an issue.

 

[Newdude]

The horizontal portion may or may not fill depending on the slope of the line

Right ? Lol. I was assuming it was level. But that's an unknown risk i wouldn't take myself.

 

[Newdude]

Exactly how do I plug a bottom drain from the inside? I'm surely not getting in 58° water.

I didn't say it was going to be fun.

 

[mas985]

Right. Lol. I'm assuming it's level. But that's an unknown risk i wouldn't take myself.

It is very unlikely to be level. Most AG pools with MDs slope downwards towards the MD. Plus the MD sump is below the bottom of the pool and therefore the connection to it is well below the bottom edge of the pool.

 

[mas985]

Some say just raise the end of the bottom drain higher than the water level and if it freezes it has somewhere to expand.

This can work for some pools but may not for all and it is highly dependent on local conditions which is probably why you are getting different points of view. There are always exceptions especially in flex pipe because there are internal ridges which can form ice plugs not allowing the ice to move in the pipe. A continuous freeze is usually not an issue as water in pipe tends to freeze from the outer surface inwards. However, if you go through several freezes and thaws, an ice plug anywhere within the pipe can then prevent the expansion of the ice so there is always some risk.

One thing that works in your favor is that the pipe is covered by the deck. This reduces heat loss from both convection and radiation which are the dominate sources of heat loss.

If you wanted to use this technique instead of blowing out the lines there are a couple of ideas to reduce risk:

• Insert 1" stiff foam backer rod into the open ended pipe to absorb the ice expansion
• Insulate the pipe to reduce heat transfer to the environment so that heat transfer to the pool water is higher and the water remain a liquid longer and freezes slower and prevents the freeze/thaw cycles that usually cause freeze damage

 

[JamesW]

I think that an airlock would probably work.

 

[Newdude]

Most AG pools with MDs slope downwards towards the MD

I can see it with flex pipe but not with rigid PVC. Your average 24 ft wide pool would need just over one length of PVC to reach the side and it would take more trouble than it was worth to bend 12 ft of pipe without throwing the drain out of level.

 

[Whynotme]

Thanks all, certainly alot to consider here. Will need to decide soon. The big tree next to the pool is starting to shed. Usually the wind blows over the pool towards the tree, so falling leaves generally fall outside of the pool area, but one good gust of wind in the other direction is going to litter my pool with leaves. Really appreciate all of the advice!

 

[Mdragger88]

Fwiw- If you use rv antifreeze it won’t hurt anything if it makes its way into the pool.