Main drains, needed?

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lwlln26

Main drains, needed?

Postby lwlln26 » Sat 16 Jul, 2011 13:59

We have a 15000 gal pool, dont know the dimensions but it is 74' perimeter and goes to 8ft deep. We are replastering and thinking of redoing the old copper plumbing. We were quoted on 3 return lines (we currently have 2) an autofill, a poolsweep line, skimmer, and split the main drain. We are kind of weary of cuttting through the gunite for the main drain. Wont it weaken the shell? One pool contracter said we dont even need a main drain, that the vaccum and skimmer would be enough circulation. What are your opinions of the main drain. Should we just close it off? Thank you.


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 drains, needed?

Postby czechmate » Sat 16 Jul, 2011 17:49

Anyone who will tell you that you do not need a main drain in a 8 foot deep pool, is not playing with a full deck. Polaris cleaner, still the best selling pool sweep on the market is based on principle to move settled dust, dirt, chlorine additives and miniscule debris to the deep, where it is sucked by a main drain.

Main drain also puts your cold water on top, cooling it , so valuable here in the deep South in the summer.
It helps to mix chemicals quickly, starting with added acid, with conjunction of pool sweep help.
Some of the most important function of the main drain is the simple fact, that without it, in normal filtering cycle you keep cleaning already clean water, since the skimmers and the fresh water inlets are very close to same water level.
The bottom water has no reason coming up to the top to be sucked by the skimmers to enter the filtering process!
Your cleaning cycle may therefore be 4-5 hours longer.

I had at one time lenghty discussion about this right here with some self proclaimed experts.
You can look it up in archive. It will amaze you.

BTW, anytime you want to dilute the pool water after big rain, in case of a high CYA and CH, you close skimmers and suck the bottom water out of the pool.
Copper lines were usually used on the top only, because of the corrosion in the dirt.
How do you know you have a copper all the way?
lwlln26

Main drains, needed?

Postby lwlln26 » Sat 16 Jul, 2011 20:14

We have just been told it would be copper. Pool was build in the 60s. We have been told its good to do the plumbing since we are doing the plaster, and that the copper will give out eventually. Others have said if theres no leak to leave it alone. We have gotten 4 estimates for the remodel and our main decision comes down if we are going to do the plumbing also while we have the deck open and plaster off. We have not pressure tested it and the pool has been empty for about 6yrs.
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 drains, needed?

Postby czechmate » Sat 16 Jul, 2011 22:16

Main drain pipe is usually imbeded directly in a rebar structure. There is no other avenue to pick up the drain and also it moves with the gunite shell during the pool setlement. (90% of all pools setle unless built on rock base ). If there is breakage of plumbing, it then occurs at the deck level, where it is accesible better than somewhere 6-9 ft deeper.
Therefore anything in the gunite structure is not accesible anyway.
The rule of thumb would be not to be fixing what is not proved to be broken.
You can test run it after plaster job and do the deck later, if it needs to be done.
Contractors are the ones who's ideas and recomendation has to be always scrutinized, since most of the time it is taylored to their advantage, either labor wise or due to the cost, that may kill the contract.
lwlln26

Main drains, needed?

Postby lwlln26 » Sat 16 Jul, 2011 22:58

We were told they would cut thru the gunite and make a new drain line. Also the drain would be split in two for safety and code reasons. Return lines would all be new also. Does the skimmer meet with the main drain line?
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 drains, needed?

Postby czechmate » Sun 17 Jul, 2011 08:04

Cutting the gunite in the deep to replace something that likely is not needed to be replaced is like having a root canal done for a toothache.
Deep side walls are constantly under tremendous stress due to the weight of concrete and volume of water. They often crack on the freeform designs, where builders eager to please the buyer make a sharp turn to the deep. Diferrence in weight of the shallow and deep is too much to ask for a rebar to hold, specially in the clay regions, like Texas.
I did my best to explain the dangers and how things work.
This is also where I split.

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