Closing (Winterizing) a Pool/Spa in northern Virginia


Well-known member
Nov 30, 2009
Hi All,

New guy here ... had pool for 4 years and did my own winterizing with no freeze damage issues, but still looking for better ways to winterize - while I don't really worry all winter, I do have moments when temps dip to low teens when the anxiety builds.

Pool and spa details aare below, but questions are:
1. given the below, can/should I leave water in the spa vice draining it (recognizing some water will still be in the plumbing below the level of the main drains)?
2. Will the plaster finish be damaged by not keeping water in it?
3. Does leaving water in it help contain the air lock I established during line evacuation?
4. Any other tips on winterizing process for this temperature area?

Thanks for such a great forum!

Specifics of pool and spa

- Pool
- rectangular (18 by 38), 3'-9', gunite, lt blue marble poly plaster
- two large lights about 30" from waterline
- shallow and deep end skimmers
- main drains at 9' depth
- Polaris cleaner on separate pump
- pump, heater, and plumbing are all inside a "pool room" connected to small patio area (no rain or wind gets to equipment)

- Spa
- semi-circular shape of same materials as pool
- plumbed independently from pool
- is located at side edge of pool, but does not waterfall into pool
- six simple jets with removable nozzles
- sides are about 24" high
- inside has two tiers, first is just below ground level and bottom of spa is about 28" below ground level
- two small lights about a foot below ground level in the spa
- blower for the jets

- I use large shop vac to blow the lines through a plumbed-in faucet fitting
- I get full air through all the returns, skimmers, jets in the spa, and spa main drains
- I DO NOT get air bubbling out of main drain (am assuming this is because of depth and lack of air volume to displace that much water)
- drain down pool to about 2 inches below tile level; this is below skimmers so use main drain to pool last couple of inches
- winter cover is tarp style plastic with waterbags around perimeter; cover rests of surface of water
- I fully blow and then vaccum/sponge out skimmers
- I don't use anti-freeze (probably would if I was another 4I00 miles north in latitude)
- This year is first I have put in empty plastic bottles in the skimmers
- I used rubber plugs for all returns (remove nozzles in spa first)
- I drain spa completely through "spa drain" function and then blow out main drains; water remains, but only a couple of inches so I leave it and hope it holds the air lock
- Have not had a chemistry issue, so usually just make sure numbers are good


TFP Expert
In The Industry
Jun 12, 2009
Exeter, PA
put rocks into your plastic containers so that they sink when place in water. This way if your skimmers fill with water they won't float out of the skimmer. If you are not getting air out of the main drain it's not blowing out properly. I can not recommend what to do here because you use a shop vac and I doubt you want to invest into a 400 dollar blower that can blow 160 inches of water. The only idea i can give you is I saw another pool company use a rubber plug with a valve stem (like the kind you would see on a car tire) this one way stem was probably used with an air compressor. This should slowly build enough pressure to allow bubbles to come up from the main drain. I personally don't use air compressors at all because even though they are high pressure their volume of air doesn't compare to the specialized blowers/vacs we use.


Well-known member
Nov 30, 2009

I forgot to say I did fill plastic containers part way with rocks to hold down ...

Understand re pressure/volume issue ... I have been told that key is to pressurize, even with just the shop vacuum, and then air lock which creates an air bubble at the top - area of plumbing deeper is protected since is so far below frost line. This seems reasonable ... but, again, it is not the right way to do it ...

With more volume, and getting bubbles, it just means are extending the bubble further into the plumbing - deeper towards the main drain, right?

Thanks for your response ...!


TFP Expert
May 20, 2007
South Central NJ
The pool returns and the skimmers need to be sealed when blowing the water out. The pool main drain gets air locked. A raised spa (12" or more) needs to be drained of water, have it's drain blown and sealed and then refilled. If you have a mesh safety cover, refill to about a foot below the tile. to allow for rain and snow melt. If you have a solid cover with no drains, a few inches to allow for snow load displacement works well.

Spas that are flush with the pool get air locked in your climate, unless you are up on a mountain and get more snow than the surrounding area. Then I would plug the drain.

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