Question about water in the main drain line

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R

Resnick

0
Sep 23, 2015
15
NJ
Hi All,

I'll start by saying that I'm a new pool owner so please excuse it if the question is a stupid one :). Okay, so we moved to a house that came with a pool in Feb. The pool had been closed for a year or 2 as the previous owners were elder. I was able to open the pool with a few minor issues. At that time I noticed that the main drain pipe was leaking in the connection where it connects to the 3 way - valve by the water pump. I bought a cloth wrap (it hardens after it gets wet) in the pool store to see if it would fix it but it didn't. I tried to remove it but I couldn't because it glued very tight and I was afraid of cutting the flex pipe. So, I didn't pay much attention since the leak was minor (only drops) and left it like that. Now, I'm getting ready to close the pool and during the process of blowing out the lines, I realized the air is leaking through the same main drain connection. So my question is, if water does come into the main drain is there a good change that it will freeze and break the pipe? I'm assuming water will eventually come in since the air I pumped will leak out. But I've read it's very unlikely for water to freeze in main drain because in this area (NJ) water will not freeze if deeper than 2 feet. Does anyone know if I should be concern or if things will be okay? any comments will be appreciated.

ps. The real fix would be to cut the pipe and re-do the piping which I'm hesitant to do because I want to re-do all the equipment piping. The pump and filter are in a small shed and whoever did the the plumbing of the equipment made a web of things which makes it very hard to do any maintenance on the pump or filter.

Note: my pool is 16' x 32'. The deep end is about 8 ' deep and the shallow end is about 3.5 - 4 '. Pool size is about 20k gal.
 
I think I understand your situation based on the description. While it may be true that you can get away with some water sitting in the main drain plumbing at the bottom of your pool some 8' underground, the water near your fitting is another story above ground. Since the air leak near your valve prevents you from pushing enough air pressure required to empty the drain line, water will continue to push its way back up close to that valve (I would think). Depending on how much water that is, the pipe could swell. Is there any way you can plug the main drain and try to use suction to pull some of the water out? Maybe if you get at least some of it out, that will allow some room for expansion above the frost level. Or perhaps allow you to add some antifreeze to hold you over. Worst case scenario, it ruptures. Maybe not a problem for the pipe itself since you plan on re-doing the plumbing anyway, but the water may continue to pour out of there from the main drain at a time when it's freezing cold and you simply can't do much to repair. Maybe with this reply and getting the post back to the top of the que form others may have another idea. Best of luck!
 
Thanks Texas Plash for the information. I'll think about putting some antifreeze through the pump intake and into the main drain line.

Duraleigh, Yes, I lowered the water to the return lines. I just measure and the water is 1' 4'' (20 inches) from the top of the pool. Do you think that's okay? Thanks
 
I'm thinking of pouring antifreeze down the line and hope for the best. I remembered that when we first moved in, the water level was very high to the point where it went into the skimmer and the leak must have been there. So, I'm hoping that the fact that water line is lower and the antifreeze might prevent the line from breaking. I guess I can lower the water a bit more too but I've read it's not good to go to low.

Here is a chart I found in case it might be helpful to anyone else. It's a has the avg frost line for the entire US.

http://sqfoot.com/pdf/US_Map_Frost_DepthAVG.pdf
 
Re: Question about water in the main drain line
The water will come back into the main drain pipe to the same level as the pool water. Are you draining your pool level to below the returns?
You have to decide if it's OK. You know your climate (1 foot 4 inches = 16 inches and the top of the pool is not really relevant.....how far below ground level is important.)
Click to expand...

Resnick:

If you have any leaks at the MD, I would definitely suggest you bring someone in (A professional to fix this). In NJ, you will find many people, with a lot of experience, who have worked or work for pool builders that work on the side. Ask your friends and neighbors for some referrals. A few dollars now protects you.

If I understand your situation correctly, even if you blow out your main drain and there is the slightest leak at the equipment pad, you will lose the air slowly. Then the water from the main drain may come back up, possibly causing problems. I had a friend who moved his filter and when the MD pipe was cut, the suction was so strong that he would have emptied the pool in hours. The professional dove in and capped the MD with something. I was not there, but showed up later. The MD is something that should be done carefully because of pressure alone. The skimmers, if completely blown out would be a different situation as you could remove 100% of the water, like I have. Even the returns could be done the same way if you drop the water level below the returns. Unfortunately, the MD is a whole different story.

The good news is you have a few months to resolve this issue. As the temperatures quickly drop here in NJ, you would only have to run the pump for a few hours (2-4 at most) and your chlorine consumption would be minimal. A few dollars spent today is a lot less than thousands spent later on serious damage.

Please keep us posted!
 
Sorry for the delay in replying. Just wanted to take a minute to say thank you for all the feedback, much appreciated. I'll probably end up calling someone and try to save myself some unwanted headache! :)
 
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