Main Drain

Stairs, skimmers, jets, drains, lighting, water features
and miscellaneous pool water fixtures and fittings.
czechmate
Swimming Pool Superstar
Swimming Pool Superstar
Posts: 401
Joined: Sat 16 May, 2009 09:20
My Pool: 16 x 32 gunite21000 gal., Diamond Brite Blue, Swimquip XL pump, DE36
Location: Texas

Main Drain

Postby czechmate » Tue 20 Aug, 2013 19:03

mas985 wrote:A pool bottom is much flatter than a toilet bottom which is more funnel shaped so "debris" is more inclined to move toward the toilet hole than the main drain. The toilet has a fairly large hole for "debris" to pass while a pool main drain has many very tiny holes which only fine dirt can pass through. A toilet uses gravity to flush while a pool use a pump to create water flow. A toilet flushing looks nothing like a main drain running (i.e. no swirling action). The physics are substantially different between the two and the toilet is going to be much more effective at removing debris than a main drain.

Also, I don't disagree that a main drain can have decent flow rate but it is usually a little less than a skimmer because the pipe lengths are longer. But even it was the same, the flow rate doesn't do much in the way of debris removal. If you don't believe me, dump a small amount of dirt directly around the main drain and see how much dirt it actually collects (without the help of a cleaner or vacuum). You will be very surprised at how little is removed.

But you are so predictable!
I wrote this piece specifically for you. And you jumped right on it. :wink:
The suction in any pool return branch is related to distance from the pump and of course the depth in the case of the main drain. My main drain is half the distance of the skimmer I use.
(The second skimmer I do not use, because filtering clean water that is spitted by inlet to the surface right next to it, I consider a waste of electricity as well as unnecessary prolonging the cycle).
Also, you completely forgot about the selector valve.
I built my first pool in 1974, so please do not patronize me with your suggestions to "watch action of the main drain". I have installed the new safety cover 2 years ago, with the new plaster and it sucks in parts of oleander leaves and the flower stems as well!
Now to the point:
With the selector valve aimed on main drain only you can actually clean fine sand dust (settled in your pool after the sand storm), just gently using the wide brush toward the main cover. You see I have done it and not just once!
It may take an hour or two, but it would take a regular pump 8-10 hours, with the pool sweep activation 10-16 hours and in the same pool without a main drain at least 3 days!!
I sincerely admire your willingness to make a spectacle of yourself here in such a clear cut argument.
Maybe you have your original opinion about the "global warming" supported by a video as well.


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mas985
Swimming Pool Pro
Swimming Pool Pro
Posts: 199
Joined: Tue 08 Sep, 2009 10:40
Location: Pleasanton, CA, USA

Main Drain

Postby mas985 » Wed 21 Aug, 2013 10:23

czechmate wrote:But you are so predictable!
I wrote this piece specifically for you. And you jumped right on it.
As are you. Remember, you directly responded to my post first after which I responded back. But isn't that the way a forum works?

Anyway, I am glad that your main drain has worked out for you but that hasn't been the case for many people. Personally, I would rather redirect flow to the skimmer to pull debris off the surface before it hits the pool bottom. But when the dirt hits the bottom of my pool, the main drain removes only a few inches around the drain which I don't believe is very useful. It doesn't improve much even when I redirect all of the flow through the main drain. This is not uncommon among pool owners.

With the selector valve aimed on main drain only you can actually clean fine sand dust (settled in your pool after the sand storm), just gently using the wide brush toward the main cover. You see I have done it and not just once!
Of course, if you use a brush it will be more effective, that was not my point. My statements where based on the main drain working in isolation without help from the pool owner. But regarding this method, there are many people on various forums who have attempted this with a clean-up at opening only to have the main drain or suction line clog with debris. So you really have to be careful with this method to only push debris that is small enough to pass easily through the covers and lines.

It may take an hour or two, but it would take a regular pump 8-10 hours, with the pool sweep activation 10-16 hours and in the same pool without a main drain at least 3 days!!
My cleaner keeps the floor spotless with only 4 hours of run time per day so I don't think this is the case for all cleaners. My cleaner is by far more effective than the main drain alone and if I don't use the cleaner for a week, the pool floor is littered with debris so the main drain really doesn't do much by itself.


But neither my opinion nor yours changes the APSP position that main drains do not help very much and in case you did not bother to read their report here are a few quotes:

The single most commonly held, yet mistaken, belief regarding drains is that they “vacuum or
suck in dirt” and somehow “clean the floor.” They do not. Remember the candle experiment?
Pool drains are no different. If a leaf is placed two inches from the opening of a flowing two-inch
pipe, it will never enter the pipe unless it is pushed in – either by a brush or by a stream of water
specifically directing it to the pipe opening. In fact, a pool left un-vacuumed for several weeks is
complete proof that the drain alone cannot clean the settled debris. Some debris does enter the
drain, by chance, but the pool will still require routine vacuuming in order to remove settled
debris. Since vacuuming, manually or via automatic cleaner, is a routine part of pool
maintenance, why rely on a drain that might remove “some” of the settled debris, but also leaves
bathers exposed to a proven lethal hazard?


You may disagree with them and that is fine but everything that they mention has been my experience and the experience of many others. They have also backed up their position with some detailed analysis and experiments so I would not dismiss it out of hand so easily.
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
czechmate
Swimming Pool Superstar
Swimming Pool Superstar
Posts: 401
Joined: Sat 16 May, 2009 09:20
My Pool: 16 x 32 gunite21000 gal., Diamond Brite Blue, Swimquip XL pump, DE36
Location: Texas

Main Drain

Postby czechmate » Thu 22 Aug, 2013 09:50

"You can lead a camel to the water but you can't make it drink" :wink: .
Free info

Main Drain

Postby Free info » Fri 23 Aug, 2013 13:21

It may take an hour or two, but it would take a regular pump 8-10 hours, with the pool sweep activation 10-16 hours and in the same pool without a main drain at least 3 days!!
I sincerely admire your willingness to make a spectacle of yourself here in such a clear cut argument.
Maybe you have your original opinion about the "global warming" supported by a video as well.czechmate
Swimming Pool Superstar


Why not just vacuum the pool it takes 10 mins compared to 1-2 hours of brushing to the drain?
So this is the big deal that you can get your main drain to work as long as you brush debri/dust towards it?
When you have it set normally it doesnt do it so you do your thing that works for you, ok.
The new pools being built today do not even have this option anymore as they use skimmers with 2 holes.
Law of physics applied.

Main Drain

Postby Law of physics applied. » Sat 24 Aug, 2013 09:24

1. Location of clean water returns and skimmer intakes are almost at the same level at the top of the pool. Just cleaned water then has reenters the skimmer again heading for the filter. There is no physical reason for it to go elsewhere.

2.Anytime the pool level rises above the most optimum suction force of the skimmer, which varies from 1-2 inches, the suction is getting diminished to the point that at the rise of 2 inches even small grass clippings will flow by the skimmer at the mere distance of 2inches and will not enter.

3. When 2 skimmers are deployed the situation worsens for two reasons. More, already cleaned water enters the filtering system and the suction at the main drain becomes too negligible to function as designed. At this point due to shared intake with other skimmer half the debris will flow by the skimmers without being sucked in.

4.During the winter months, in southern climates, where hard freeze comes often as a surprise and where a larger percentage of the pools exists, main drain protects the equipment from accidental freeze.
Warmer water stored at the bottom of the pool is used to prevent pool from freezing, while running on freeze-stat. While surface water is being super chilled by winds, bottom water warmed by the deep concrete and warmer surrounding soil, is effectively mixed to supply filter and water heater preventing freeze of piping and equipment.

5. Conundrum that remains to be explained here is this: If the main drain is so ineffective as to pull anything as small as a leaf laying next to it, why is it deemed by the "pool experts" to present such a clear danger to a swimmer in motion?
Free Info

Main Drain

Postby Free Info » Sat 24 Aug, 2013 16:31

Calif. Enacts Pool Drain Bill
by Scott Webb October 4, 2012 9:31 AM 31

California Governor Jerry Brown recently signed AB 2114, a bill sponsored by SPEC that will modernize building codes governing the construction of swimming pool and spas. There is nothing in the legislation that requires changes to existing pools or equipment, but by explicitly allowing the construction of drainless pools, the new law may have an effect on the future of the industry.

AB 2114 spells out support for the construction of drainless pools, so long as such alternative methods of circulation comply with the turnover requirements contained in Title 24.

“Because AB 2114 will be enacted into law,” said SPEC president John Norwood, “there will no longer be a requirement for a drain or main drain on the bottom of the pool so long as the pool can comply with the water quality standards.”

“This is one of the most important and significant bills ever enacted by SPEC”, added William Rowley, SPEC board member and President of Rowley International. “AB 2114 eliminates the danger of suction entrapment beyond the VGB Act because the bill will allow the design and construction of pools without man drains or suction outlets. SPEC should be commended for this outstanding accomplishment.”

AB 2114 also eliminates the terms “drain and main drain,” and replaces them with the term “suction outlet” everywhere these terms currently appear in California statutes. The new law also updates the California Virginia Graeme Baker (VGB) statute to require that suction outlet grates must meet the ANSI/APSP-16 standards or any successor standards adopted by the Consumer Products Safety Commission.
Drainless pool bill?

Main Drain

Postby Drainless pool bill? » Sun 25 Aug, 2013 09:29

I like that.
We should do that right after we repeal the "useless" Obama Healthcare.
Than we can hire more normal, in our universities educated educated people from Asia and Europe. :lol:

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