New 18x36 pool with no main drain?

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mas985
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New 18x36 pool with no main drain?

Postby mas985 » Tue 10 Nov, 2009 16:17

Sorry, forgot to add this link from the APSP:

Myth
"A main drain is essential in a pool to maintain healthy water."

Science does not support this conclusion. In fact, science concludes just the opposite. In a 2006
issue of Fluent News, the leading manufacturer of computational fluid dynamics software, an
article ran that compared pools with and without drains. The conclusion: there were no
significant differences between the circulations of the two pools. In fact, the skimmer-only pool
was slightly better.


Also, this link from Pool and Spa News:

Opponents often argue that the drain removes dirt and debris. This is only true when debris is actually pushed to the drain. In-floor cleaning system designers say that if the drain is not built with larger openings to accept debris, and precisely located jets are not arranged on the floor to push sand and leaves to the drain, it won't be effective.


Mark
Hydraulics 101 ; Pump and Pool Spreadsheets ; Pump Ed 101
18'x36' 20k gallon plaster/gunite pool, 1/2 HP 2sp pump, Aqualogic PS8 SWCG, 420 sq-ft Cartridge Filter, Solar Panels, 6 jet spa, 1 HP jet pump, 400k BTU NG Heater
Guest

New 18x36 pool with no main drain?

Postby Guest » Thu 12 Nov, 2009 00:00

Thanks guys for all the info. It's been very helpful. We have decided to not install the drains. The info on the scientific study was great. Thanks.
Gullible

New 18x36 pool with no main drain?

Postby Gullible » Thu 12 Nov, 2009 13:48

So was the report on the weapons of mass destruction.
You are exactly the type of customer your contractor looks for.
Now get ready to work hard to keep it clean an algae free.
czechmate
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New 18x36 pool with no main drain?

Postby czechmate » Fri 13 Nov, 2009 20:05

Gullible wrote:So was the report on the weapons of mass destruction.
You are exactly the type of customer your contractor looks for.
Now get ready to work hard to keep it clean an algae free.


Some people could not feel the truth if it bit them in the butt.
I guess that's what they call diversity.
schnoz

New 18x36 pool with no main drain?

Postby schnoz » Sat 23 Jan, 2010 22:20

I am currently having a pool built and spent the better part of the last two months researching just about every aspect of pool design and construction. I have found research papers, backed up by extensive fluid modeling and practical applications, that confirm bottom drains are unnecessary for pool water circulation. Water is moved by pushing, not pulling, and strategically placed skimmers and returns have been proven to be as effective, and in some cases more effective, circulating water as pools with bottom drains. If you have an in floor cleaning system, then sure, a bottom drain is necessary. But, if you have a suction side cleaner, it is completely unnecessary even in deep pools. I will not be installing bottom drains.
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New 18x36 pool with no main drain?

Postby lbridges » Sun 24 Jan, 2010 11:06

Say if the house was renter occupied (and didn't have the best training, or the cost concerns that an owner has)...Without a drain (in a pool with a defined deep end), and no mechanical device in the water (cleaner), aren't there bad things that could happen when acid is dumped in, etc.?
Me...
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New 18x36 pool with no main drain?

Postby Me... » Thu 15 Apr, 2010 21:45

Considering a set of main drains will be hauling most of the water from the pool I do not know how the rocket scientists and politicos can say Main Drains do not contribute to circulation, they are critical. I have read the stories and reports and watched the videos and they just further convince me there is no reason to not install them.

Dual Main drains with proper flow characteristics present no hazard and I don't think anyone can point out an instance where there has been an issue .......... and I do emphasize proper installation. Many appear to built by morons.

I love floor inlets but not necessarily floor cleaning systems. Pulling the used dead water with the heavy debris in it from the drains and pushing clean treated water in from the bottom will go an extremely long way towards ensuring the chlorinated water actually gets into the bottom corners.

Probably most I know in the business that have actually worked on pools have seen a myriad of pools where a vacuum had to be left in the drainless pool in order to clear it up. As with most things there are of course going to be exceptions but I would never build a pool without Main Drains.
D Maynard

New 18x36 pool with no main drain?

Postby D Maynard » Sat 12 Mar, 2011 00:03

Mark,

You are absolutely correct in your analysis. For a pool less than 5ft deep, a main drain is pretty much useless. The returns do over 95% of the work in circulating the water, with the skimmers and drains doing the rest. The only time a main drain really does anything is when it is placed in the dead zone areas of a pool, and then it is effective. When it comes to liquids and gases, the force of suction force is not effective as pushing the it for mixing.

To illustrate this, all one has to do is put their hand close to their mouth and inhale deeply, then blow back out. Huge difference.

Simply fluid dynamics. I should know. I am a mechanical engineer who does FEA analysis for a living.

If I were a lesser man, I would insult the intelligence of the full of opinion but lacking of knowledge of czechmate, but I believe he has done that quite effectively on his own.
czechmate
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New 18x36 pool with no main drain?

Postby czechmate » Sat 12 Mar, 2011 22:24

D Maynard wrote:Mark,

You are absolutely correct in your analysis. For a pool less than 5ft deep, a main drain is pretty much useless. The returns do over 95% of the work in circulating the water, with the skimmers and drains doing the rest. The only time a main drain really does anything is when it is placed in the dead zone areas of a pool, and then it is effective. When it comes to liquids and gases, the force of suction force is not effective as pushing the it for mixing.

To illustrate this, all one has to do is put their hand close to their mouth and inhale deeply, then blow back out. Huge difference.

Simply fluid dynamics. I should know. I am a mechanical engineer who does FEA analysis for a living.

If I were a lesser man, I would insult the intelligence of the full of opinion but lacking of knowledge of czechmate, but I believe he has done that quite effectively on his own.


Bravo Mr. mechanical engineer.
Since you so skillfully compared the basic action of a commode to a checking one's bad breath, while you just could not give up the chance to insult my opinion on the basic reason for a main drain, you asked for this reply.
The cleaning of the swimming pool is NOT ABOUT MOVING WATER!
It is rather about most efficiently taking the dirty water AND BOTTOM DIRT, DUST AND DEBRIS to the filter with minimum time, trying to minimize mixing the already cleaned water with the dirty one.
That is why Polaris is still the best pool cleaner out there and still the most expensive.
The time needed to completely clean the pool is called the cycle. It makes difference if it is 4hrs or 8 hrs!
Without main drain it is more like 12 hrs.
Without main drain the bottom dirt, sand, grass clippings, bugs,and other small debris will be just circulating around the perimeter at bottom. Skimmers will be taking in the clean water that the return will bring in at the water top.
So the dirty water including the debris has no reason or is in any way forced to come to the skimmers while I am sucking perfectly clean water back to the filter.
I guess you must be calling this the "Yankee ingenuity", Mr engineer.
Main drain also gives you the additional chance to clean the sand after the sandstorm by closing the skimmers and suck the bottom dirty water only directly to filter.
And i can assure you, the suction at bottom added by pressure of 9ft of water table is more than sucking on your hand or your thumb!( Where you most likely got YOUR GREAT KNOWLEDGE).
BTW, when you get a chance, post a picture how you brush the bottom fine dust toward your skimmers.
I will have it framed.
czechmate
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Posts: 401
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My Pool: 16 x 32 gunite21000 gal., Diamond Brite Blue, Swimquip XL pump, DE36
Location: Texas

New 18x36 pool with no main drain?

Postby czechmate » Sun 13 Mar, 2011 08:44

Me... wrote:Considering a set of main drains will be hauling most of the water from the pool I do not know how the rocket scientists and politicos can say Main Drains do not contribute to circulation, they are critical. I have read the stories and reports and watched the videos and they just further convince me there is no reason to not install them.

Dual Main drains with proper flow characteristics present no hazard and I don't think anyone can point out an instance where there has been an issue .......... and I do emphasize proper installation. Many appear to built by morons.

I love floor inlets but not necessarily floor cleaning systems. Pulling the used dead water with the heavy debris in it from the drains and pushing clean treated water in from the bottom will go an extremely long way towards ensuring the chlorinated water actually gets into the bottom corners.

Probably most I know in the business that have actually worked on pools have seen a myriad of pools where a vacuum had to be left in the drainless pool in order to clear it up. As with most things there are of course going to be exceptions but I would never build a pool without Main Drains.



To D. Maynard:

You can lead a camel to the water, but you can't make it drink...........

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