Ok so in the next couple months I'll be building my own 20x40 liner type IG pool.... It would save me time, money, effort not to plumb a main drain (or 2).... I mean how often do you use that anyway? This is my first pool so I'm not sure?? But my idea would be to just use a submersible pump to pump the water out if/when I need to drain it.... Just a thought.... Any info is appreciated...
Do I even need a main drain?
- Thread starter WhoDat?
- Start date
By moving water you mean it's constantly sucking water through the filter like the skimmer?? Or will you just be able to turn it on once in a while to move water?
- May 3, 2007
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This is one subject that certainly does not lack for coverage:
do-i-even-need-a-main-drain-t40077.html
deep-end-main-drain-vs-downward-pointing-return-t39071.html
should-i-go-with-pool-without-main-drain-t38222.html
to-main-drain-or-not-to-main-drain-t33788.html
main-drain-t24929.html
main-drain-t23533.html
As you can tell, I am clearly in the "don't need" camp although I do have one in my pool. But I wouldn't really miss it much if I didn't have and if I ever build another pool, I will probably skip the main drain.
They do nothing for cleaning and/or circulation that can't be done by other things.
For circulation, a lower return or even a return pointed downwards does far more for circulation than a main drain. Main drains these days are designed to keep the water velocity as low possible so they will draw water from near the drain and above it but that is about it. Where as a return can have very high exit velocity and affect the entire pool.
For cleaning, an automatic cleaner will do far more for cleaning than a main drain. Again because of the low entrance velocity, they will not attract bottom dirt beyond a few inches of the drain.
They may be useful for draining the pool with the main pump, but most pumps will start drawing in air as the water level drops so even that is not enough reason to go with a main drain.
Also, if you have problems with the main drain plumbing, they are much more difficult to fix than a side return or skimmer plumbing which can be reached with a little digging.
do-i-even-need-a-main-drain-t40077.html
deep-end-main-drain-vs-downward-pointing-return-t39071.html
should-i-go-with-pool-without-main-drain-t38222.html
to-main-drain-or-not-to-main-drain-t33788.html
main-drain-t24929.html
main-drain-t23533.html
As you can tell, I am clearly in the "don't need" camp although I do have one in my pool. But I wouldn't really miss it much if I didn't have and if I ever build another pool, I will probably skip the main drain.
They do nothing for cleaning and/or circulation that can't be done by other things.
For circulation, a lower return or even a return pointed downwards does far more for circulation than a main drain. Main drains these days are designed to keep the water velocity as low possible so they will draw water from near the drain and above it but that is about it. Where as a return can have very high exit velocity and affect the entire pool.
For cleaning, an automatic cleaner will do far more for cleaning than a main drain. Again because of the low entrance velocity, they will not attract bottom dirt beyond a few inches of the drain.
They may be useful for draining the pool with the main pump, but most pumps will start drawing in air as the water level drops so even that is not enough reason to go with a main drain.
Also, if you have problems with the main drain plumbing, they are much more difficult to fix than a side return or skimmer plumbing which can be reached with a little digging.
They say to add another suction line in the side of the pool if you get rid of the drain.... What's that all about? That seems more dangerous to have a suction in the side wall rather than all the way at the bottom.... And also some say it messes with the pump if you don't have a main drain..... I'm leaning to the no main drain side, but I just want to be sure before I skip it!
My pool in NJ has a skimmer and main drain and I find the main drain helps tremendously with small debris and small items that fall to the bottom. Having 2 goldens, it does a great job of collecting the hair in one spot, which I manually pull out.
The pool in FL has 2 main drains and collects the debris from the in floor cleaning system (also collects sand that blows in from around the pool - from the pavers).
My vote is go for the main drain.
The pool in FL has 2 main drains and collects the debris from the in floor cleaning system (also collects sand that blows in from around the pool - from the pavers).
My vote is go for the main drain.
- May 3, 2007
- 16,828
- Pool Size
- 20000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Hayward Aqua Rite (T-15)
WhoDat? said:
That is for the rare situation where the water level might drop below the skimmer and to protect the pump they will plumb a suction line below the skimmer at a lower depth into the second port of the skimmer. A valve is used so that this suction line is normally closed but when the level of the water drops, a float in the skimmer seals the skimmer path and then the valve in the bottom of the skimmer releases so that water can be drawn in from the lower point. This isn't really needed if you have an autofill but some people like the idea of extra protection. As for safety, it can be plumbed fairly low and out of the way and they use the anti-entrapment covers and can also be plumbed into pair so that shouldn't be an issue. Plus, they aren't normally activated unless you want that. The following link shows how this is usually plumbed:
Skimmer Equalizer
I don't remember if I posted this link before, but the APSP did a case study on main drains and came to the conclusion, that they were not really necessary:
APSP Case Study
Pool and Spa News Article
Also, here is a video showing how a 18"x18" main drain running at 800 GPM hardly moves the water. This is equivalent to a main drain pair running at 34 GPM.
Main Drain Video
Reading that APSP Case Study makes me think my main drain was PURPOSELY disabled when the new skimmer was put in. Makes sense to me now.
It amazes me how clean my water stays with just one skimmer in the middle of a 44,000 gallon pool.
It amazes me how clean my water stays with just one skimmer in the middle of a 44,000 gallon pool.
mas985 said:
Ok thanks!! I don't think I'll have an automatic fill line.... However I don't plan on ever winterizing it either... I'm in south Louisiana .... So I'll probably never close it.... But the idea of the lower drain isnt bad... But I like that it's not necessary.... I think it would save me time and money to just add a lower return in the deep end facing down toward the center of the deep end.... Thanks for all the replies!!! Any info is always appreciated!!
Side wall suctions are pretty SOP where I am, at least in vinyl pools. They are usually put in about 18 inches or so below the top of the pool in the deep end. Mine is plumbed on a separate line back to a 3 way valve at the pump. I did have a leak a couple of years ago and it saved me from running the pump dry. I nkow theres a big differecne of opinion, but I think it helps with circulation (not intending to start a discussion over it, but it's what I think, as well as a lot of builders). The other thing it helps with is manual vacuuming. I have a robot, but sometimes i need to manually vacuum. If you only have the skimmer, the vacumm head can get sucked down on the pool surface where you cant even move it. Letting a little suction off onto a main will really help make vacuuming a lot easier. My neighbor has only a skimmer and he curses it every day when he vacuums that he doesnt have a side wall suction.
As far as safety goes, its not an issue. They are plumbed using 2 suctions lines, a couple a feet apart with anti entrapment safety covers. If it were mine, i'd do a side suction.
As far as safety goes, its not an issue. They are plumbed using 2 suctions lines, a couple a feet apart with anti entrapment safety covers. If it were mine, i'd do a side suction.
- May 3, 2007
- 16,828
- Pool Size
- 20000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Hayward Aqua Rite (T-15)
bk406, you may want to check your skimmer because most installations of side wall suction ports as shown in the pentair link I posted, are normally shut off so you actually don't get any suction flow from that port unless there is a problem.
Also, even if that suction port was normally operating, having a return in the same location as that suction port instead would provide much better circulation.
Also, even if that suction port was normally operating, having a return in the same location as that suction port instead would provide much better circulation.
It's not plumbed that way. It doesnt hook into the skimmer at all. The reason it saved me when i had a leak was that i shut the skimmer down completely during the time it took to repair the leak and still was able to operate the pool.mas985 said:
As I said, I'm not here to argue that pointmas985 said:
- May 3, 2007
- 16,828
- Pool Size
- 20000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Hayward Aqua Rite (T-15)