Main Drain Question

nocaster

Well-known member
May 18, 2007
53
Enid, Oklahoma
#1
This forum is getting better every day.

I have a question about my main drain. It is plumbed up to my skimmer instead of directly to the pump. The pool is an IG fiberglass and my best guess is that it was built about 25 years ago. Will a drain set up like this still get some flow due to siphoning action when the pump is running? I've tried brushing small debris towards the drain and I don't ever see anything move into it. I know it's not plugged because water will siphon into the skimmer if I block the opening and let the pump take out the water in the skimmer below the pool water line. Is this a normal configuration for a main drain?
 

TheOne

LifeTime Supporter
Mar 28, 2007
167
Houston, TX
#2
Yes for the flow answer but it is obviously a bit more difficult to modify your flow with your setup. Yours is probably a "normal" setup but not ideal. Several pool builders I interviewed looked at me like I was crazy for asking for each skimmer and main drain to be plumbed separately back to the equip pad. Finally I found a builder that did this as their standard and I knew I had a good company.

Check to see if you take out your skimmer baskets if the opening to the suction pipe is threaded. Meaning you could put a threaded cover or threaded reducer if needed to adjust the pipe size and/or flow at the skimmer. That would be one way to boost flow at the main drain. I have valves at the equip pad to adjust flow but this might be an option for you. Just beware that you will be effecting the psi of your system by restricting the flow. This is generally not a problem if you pipe size is on the larger side.
 

duraleigh

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Apr 1, 2007
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#3
nocaster said:
Is this a normal configuration for a main drain?
Normal? Frequently. Correct? No!!

You can purchase a balancer that will solve your issue. It's a clever device that "sucks" down to the bottom of the skimmer, under the basket, and will pull water from the main drain. While it's quite simple, you literally have to hold it in your hands to understand how it works. I have Sta-rate skimmers and the sta-rite number on this balancer is 8650-39. Mine has been trouble free for three years. Probably less than twenty bucks.
 

nocaster

Well-known member
May 18, 2007
53
Enid, Oklahoma
#5
duraleigh said:
nocaster said:
Is this a normal configuration for a main drain?
Normal? Frequently. Correct? No!!

You can purchase a balancer that will solve your issue. It's a clever device that "sucks" down to the bottom of the skimmer, under the basket, and will pull water from the main drain. While it's quite simple, you literally have to hold it in your hands to understand how it works. I have Sta-rate skimmers and the sta-rite number on this balancer is 8650-39. Mine has been trouble free for three years. Probably less than twenty bucks.
I'm pretty sure my skimmer is a Sta-Rite. The drain hole is just above the basket and the opening is towards the pool wall. I'm googling that part number but not finding anything.
 

lovingHDTV

LifeTime Supporter
May 25, 2007
529
Round Rock, TX
#6
lovingHDTV said:
Interesting as my main drain is plumbed the exact same way. How would you tell if the flow is set properly?

thanks,
After looking online I think I may have one of these things. In my case it is a flow check valve thing where the flow through the valve is controled by closing the hole. I never knew what this thing was so I just pulled it out of the skimmer.

Mine looks like item #3 if that helps anyone:
http://www.poolcenter.com/parts_skimmer ... kimmer.htm

How would you adjust this thing? Is there a recommened amount of flow from the main vs the skimmer?

thanks,
 

nocaster

Well-known member
May 18, 2007
53
Enid, Oklahoma
#7
lovingHDTV said:
lovingHDTV said:
Interesting as my main drain is plumbed the exact same way. How would you tell if the flow is set properly?

thanks,
After looking online I think I may have one of these things. In my case it is a flow check valve thing where the flow through the valve is controled by closing the hole. I never knew what this thing was so I just pulled it out of the skimmer.

Mine looks like item #3 if that helps anyone:
http://www.poolcenter.com/parts_skimmer ... kimmer.htm

How would you adjust this thing? Is there a recommened amount of flow from the main vs the skimmer?

thanks,
Does your drain line connect to the plumbing underneath the skimmer? Mine is actually connected to the skimmer above the basket. I could see how reducing the flow from the skimmer would pull more from the drain if they connect under the skimmer.

A side view would look something like this:
Code:
Top of Skimmer

|             |
 |           |________
 |            ________  To Drain
 |Basket |
 |           |
  \_      _/
      |  |
      |  |
      |  | 
      |  | To Pump
er....my ASCii art is not rendering correctly.
 

lovingHDTV

LifeTime Supporter
May 25, 2007
529
Round Rock, TX
#9
nocaster said:
lovingHDTV said:
lovingHDTV said:
Interesting as my main drain is plumbed the exact same way. How would you tell if the flow is set properly?

thanks,
After looking online I think I may have one of these things. In my case it is a flow check valve thing where the flow through the valve is controled by closing the hole. I never knew what this thing was so I just pulled it out of the skimmer.

Mine looks like item #3 if that helps anyone:
http://www.poolcenter.com/parts_skimmer ... kimmer.htm

How would you adjust this thing? Is there a recommened amount of flow from the main vs the skimmer?

thanks,
Does your drain line connect to the plumbing underneath the skimmer? Mine is actually connected to the skimmer above the basket. I could see how reducing the flow from the skimmer would pull more from the drain if they connect under the skimmer.

A side view would look something like this:
Code:
Top of Skimmer

|             |
 |           |________
 |            ________  To Drain
 |Basket |
 |           |
  \_      _/
      |  |
      |  |
      |  | 
      |  | To Pump
er....my ASCii art is not rendering correctly.
Yes my drain connection is below the skimmer.
 

duraleigh

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Sebring, Florida
#10
nocaster,

Ouch! that'll be a tough fix. Obviously, you need to restrict the flow from the pool into the skimmer but I can't picture anything that makes sense. I'd try hard to identify that skimmer model and give their tech folks a call....they may make something. Like HDTV, my skimmers have entrance and exit ports on the dead bottom, well below the skimmer basket.
 

Buggsw

LifeTime Supporter
Apr 22, 2007
925
Arizona
#11
Gosh, I love this place. Now I know exactly what that little spaceship looking thingy really is and what it really does. Although, I once had to replace said spaceship looking thingy and when I described it that way to the pool store guy, he led me to the right thing. :lol: I had no idea that it was controlling the main drain suction/flow.
 

nocaster

Well-known member
May 18, 2007
53
Enid, Oklahoma
#12
After searching around I found a sta-rite/swimquip vacuum plate that fits over the basket. This should sit above the main drain hole. It has a fitting to put a hose on, but I could probably put a rubber stopper in it and get full flow from the drain. That would probably be good enough for brushing dead rolly pollies into the drain.