Sealing entire main drain

[PR David]

We bought a house knowing the 1975 (+/-) built pool had a leak. After a professional leak detector came out and told us that the leaks were around the tiles, we patched all tile grout and still the water level went down about an inch a day. Since we are still losing water even with level below the tiles, tested all returns and skimmer with no leaking, it is obvious the main drain is the culprit. A prior owner plugged the main drain suction line with epoxy putty which probably meant there was a leak in that line. Since we don't have the money to replace that line, we want to cover the entire main drain to eliminate the leaking for the time being. We do not want to permanently fill in the main drain so are looking for something that will seal the drain. Our local pool expert says there isn't a solid cover to replace the perforated one. Is this true? If so, is there another way?

[Yasmar75]

How did your professional leak detector test all the returns?

What makes you so sure it's the main drain, it could be that the shell is cracked.

Also if you plug the main drain, how are you going to get the water back to the circulation pump?

[PR David]

The returns were tested with circulation off and dye. He claimed that a pressure test was not possible with our system.
The main drain pipe was sealed with putty by a prior owner. The assumption is that there is a leak there.
Water is returned to the pump via the skimmer.

Update: Further testing indicates that the main drain is not the leak source. So, Yasmar75 may be right that the shell is cracked (if by shell he means the pool walls). We now think that there is a leak somewhere in the tiles and/or grout. Dye testing didn't reveal anything we could see, but its difficult as the leak is slow. It takes over 24 hours for the water to lower about an inch. Any ideas out there on a good way to test for tile/grout leaks?

[Yasmar75]

My advice would be to get "pipe test plugs" and pressure test all pipes.

[img]http://uploads.tapatalk-cdn.com/20160324/c57cc73e2d08227f00c3318df34a8433.jpg[/img]

If not seal all the pipes and returns with the plugs, fill the pool and wait and see how many tiles the water level goes down ever day. Then you can work out how much water you're losing, giving you a rough idea of how bad it is.... Also check all light fittings for losses....

Also tap around the bottom edges of the pool (with small engineers hamer) and listen to see if it's bossed. (Hollow sound)

[Yasmar75]

My advice would be to get "pipe test plugs" and pressure test all pipes.

[img]http://uploads.tapatalk-cdn.com/20160324/c57cc73e2d08227f00c3318df34a8433.jpg[/img]

If not seal all the pipes and returns with the plugs, fill the pool and wait and see how many tiles the water level goes down ever day. Then you can work out how much water you're losing, giving you a rough idea of how bad it is.... Also check all light fittings for losses....

Also tap around the bottom edges of the pool (with small engineers hamer) and listen to see if it's bossed. (Hollow sound)

[PR David]

We have plugged all returns (and the skimmer) and still lose about 1/2 inch a day. Have not tried using a hammer on the pool yet. Please explain what we need to do IF there is a hollow sound.

[Yasmar75]

If you get a hollow sound it usually means the tiles have lifted from the shell due to water ingress. What also means there's a good chance the water is getting out the shell in that area...

[PR David]

If you get a hollow sound it usually means the tiles have lifted from the shell due to water ingress. What also means there's a good chance the water is getting out the shell in that area...

Okay, now we're getting somewhere. There is one perimeter tile that sounds extremely hollow. Any recommendations on how to fix that? I suspect I have to dig out the grout, remove the tile, and then repair and replace.

[Frustrated!!!!!!!]

I have the same problem with my main drain in our in ground pool in fact that is one of the questions I have in my post. I am questioning as to whether the whole thing can be covered over I do not have the money to dig up the main drain line.