Double Main Drain Closing question

[noelc]

First time owner of pool and first time closing. I just did a dry run of my closing steps and have a question around the main drain. I have a double main drain, with 8ft deep end. I attached a air compressor at 30PSI and blew out the main drain line.
However only one of the main drains had air coming out. The second, further drain from the system did not blow any air. They are daisy chained as follows:

Filter-------0-----0
#1 #2
The further drain did not blow any air.

Is this normal or should I be concerned about a clog?
Do I need to use more pressure or something with higher volume of air?
If I can not "air Lock" this second drain how much of a concern is this living in Southeast PA?

I did this same procedure on my Spa double drain and did see air from both drains.

Thanks, Noel

 

[jblizzle]

Welcome to TFP!!!

I would think that is normal. All the air is going to escape from the first drain that it encounters. A compressor or blower will not have enough air flow to get air to come out the 2nd one.

The idea is to get the water in the pipe as far down into the ground as possible as it would be more likely to freeze up closer to the surface of the pool/ground.
The water at 8 feet down in the ground is not likely to freeze solid.
Northern MN frost line is 5 feet down.

 

[JamesW]

The drains should be Teed together near the drains. As long as one got bubbles, you should be good.

 

[noelc]

Thanks. And yes you are correct they are T'd. See attached picture.

I would think that they both should blow air, but agree 8 feet down is likely not to freeze solid here.
I am also not planning on putting antifreeze in the lines.

 

[JamesW]

Most likely, they are not perfectly level. Even a tiny bit of slope will cause all air to go through just one drain. As long as one bubbled, you're good.

If you used a high volume blower, you probably would have gotten both to blow, but a compressor is low volume and will preferentially go to the higher drain even if the height difference is small.

 

[Neemer]

Thank you for asking this question, as I encountered the same situation with mine. I had a pool company close my pool last year and he used a cyclone blower. Man, that thing puts out the air. He had bubbles roaring thru everything.

 

[noelc]

That is very good to know. While I don't think I'm going to buy a Cyclone, I am going to try to adapt a shop vac and see what results I get vs compressor. I'll try to post my results to this thread if I get to it in the next couple days.

 

[JamesW]

A shop vac won't blow out an 8 ft main drain.

If you already got it to bubble, it's as good as it's going to get.