Deep End Main Drain vs. Downward pointing Return

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C

cgio

0
Oct 6, 2011
5
Richmond Hill, Ontario
I am planning to install a new vinyl pool, 16'x34'x28' Full 'L', with an 8' deep end. Total approximately 25,000 gallons I believe.

1 quote I've received includes 2 main drains installed 3' apart. Others have quoted no main drain and instead, included an additional deep end return pointed downward to sweep the bottom and assist with recirculation. Not really sure which way to go and looking for advice. I'm also planning for a Polaris 9300 cleaner - not sure if this impacts the decision.

I'm in Ontario, Canada so I'll be closing the pool for about 6 months each year.

Other info on the proposed pool:
- Dell Ozonator
- Offline Chlorinator
- Cartridge Filter
- 300,000 BTU heater
- 1 HP pump
- 4' Sheer Descent water feature in deep end w/ additional pump
- 2 skimmers
- 4 other returns in pool

Thanks in advance for any help,
Gio
 
Welcome to TFP!

Unless this is an indoor pool, you don't need the ozonator. The sun gives you all of the UV light you need for free. :goodjob:
 
Having a main drain is nice, but hardly essential. Main drains have advantages, but they are also are more likely to have problems down the road. As a general rule I recommend against main drains in a vinyl liner pool due to the small additional risk of leaks, but many people have them and love them.
 
cgio said:
What are the advantages and disadvantages of a main drain vs. additional return?
Click to expand...

Personally, I don't believe that there isn't anything that a main drain offers over a lower return. A lower return will provide much better circulation than main drains due to the higher exit velocity. Plus main drains don't really keep the bottom any cleaner other than a few inches around the drain and they aren't very useful in sucking up debris pushed toward them since most now have a anti-vortex covers which have very small openings. A vacuum, auto or manual, is much better at keeping the bottom clean.

Plus given the number of people that have had main drain leaks and the fact that they are the most difficult item to repair on a pool, I would avoid them. In fact, I would avoid all in-floor plumbing if possible.
 
If you have a main drain you are less likely to have the skimmer(s) clog with leaves and the pump starve for water in the fall, since water can still come from the main drain. Main drains also make it completely simple to get good deep end water circulation. You can get good deep end water circulation in several other ways without a main drain, but it requires a moments thought and proper aiming of the return jets. With a main drain it doesn't require any thought at all.

If you follow the water balance suggestions here you are very unlikely to have PH problems because of a SWG. 95% of PH problems with a SWG come from people who insist on keeping their TA too high, which causes the PH to drift. Lower your TA to more reasonable levels and there is no longer a problem (unless you have extreme levels of aeration, ie a negative edge pool or huge waterfall).
 

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You can use side wall suction ports instead of a main drain to prevent the pump being starved of water so again, I see no need for a main drain and it just creates one more failure point. Also, with the bypass wall ports, there will be no difference in efficiency.
 
Just some thoughts:

Do sidewall suctions create a greater risk for hair being pulled into it? Young girls for example?

Main drains are now plumbed together on larger lines then returns, water flow is greater with less pull and less chance of hair being sucked into it.

Just curious as to what builders recommend and whether its due to costing over what is actually needed and should be installed. A friend of mine, has a 16 x 32 inground and his builder installed one main drain and its directly plumbed to the bottom of his skimmer, the only reason I see this being done is simple, cheaper for builder and more of a hassle for pool owner. If I had to do mine again, I would have main drain the way mine is, I can control water flo at pump with two 2" lines coming in, one from Skimmer and one from Main Drain. I would then insist the builder find out where the prevailing wind is, put a skimmer in its line and have another skimmer on the other side.
 
If a bypass and float valve is used in the skimmer and side wall suction port, the side wall port should only be active if the skimmer is clogged or water drops below the skimmer so under normal conditions, there should be very little flow rate through that port. Plus you can plumb the side wall as deep as you want if it is a concern and they make anti-entrapment covers for those as well.
 
Note: Skimmer equalizer lines are considered submerged suction ports, and as such, they are required under the Virginia Graeme Baker Pool & Spa Safety Act to be covered with a compliant cover.
 
i have both...double main drain and lower return. not having the main drains should save you 3-400$ in parts...plus some in labor...should be quite a bit as I watched my pb fight watertable issues and it would have saved MANY hours not having the floor drains... i am not advocating for or against, i have not had my pool long enough to say, just that if you don't have the floor drains, a lower return would not be a "fair trade" dollar wise in my opinion

ps...i have been working my 9300xi hard...i left the solar cover off for a few days and there happend to be 70km hr winds. i could not see half the bottom of my pool for all the leaves that got blown in. the 9300xi worked like a champ...i would have to pull her out every 20 min or so to empty the filter which was completely jammed...
 
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