Leaking Pool?

[notime]

Here are some questions for all of you knowledgeable people. I hope someone will suggest a solution that can benefit many owners of leaking pools. And I will definatelly appreciate any positive comments. Thank you!

My pool is 1.5 year old. It is rather large 6m x 12m concrete pool tiled up with 10x10cm blue tiles. The pool has "infinity edge" on one side and the balast tank below it. It is a salt water pool but I doubt that this make any difference here.

Since it's conception I have noticed the water dissapearing from it. My builder didn't want to know and suggested that water dissapears due to vaporation. Strangelly enough it happens irregardles of cloudy or sunny days. Even more strange is fact that the salt level also constantly goes down which I belive is due to the fact that the pool leaks and I have to add fresh water to it all the time. How much? About 200 liters a day! By the way .. my builder also claimed that salt vaporates as well!

I tried many ways to locate the suspected leak including underwater swims with a bottle of Betadine to colour the water at suspect locations and observe if it gets sucked into some hole. I filled the PVC pipes for underwater light cables that I suspected of channeling some water out. I made sure that the loss of water doesn't happen due to overflowing of the balast tank.

Now some questions:

Is that possible that water may leak through the non-water-proof grout between the tiles and the concrete shell?

Is is possible to test the PVC water pipes without "preassure testing" that would require emptying of the pool?

Any other ideas of how to find the leak?

I have read somewhere that 90% of pool in Koh Samui where I live have leaks. Hmmm ....

[Chaichara]

I have just returned from visiting a friend on a brand new luxury development on Samui where all the hoses have identical, in-ground concrete pools. Of all the houses sold so far, 25% have leaking pools. If you have a proper contract wit the builder, it should certainly be fixed under guarantee - a good builder will guarantee his work for at least two years, if not more.

The main reasons for leaks are incorrect construction - typical in pools that are built by house builders rather than pool specialists. The causes are often:

- No waterproofing agent in the concrete. hairline cracks i the concrete from being allowed to 'dry' in the hot sun rather than being kept damp and allowed to cure slowly.

- Non use of rubber 'water-stop'

- Non use of special water-barrier tile adhesive.

- Insufficient sealing around the underwater light conduit, maindrains, water nozzles, and anything else that goes through the floor and walls.

Generally, if everything else is OK, even if the grout is flaking out from between the tiles, this should not cause a leak - many concrete tanks are constructed without being tiled on the inside.

Try emptying the pool by stages and when the water level is just below any of the lights and ports, see if the water continues to dissappear. If it does, there are no easy solutions. It may mean a complete retiling job after correctly sealing the walls and floor..

Edited December 25, 2008 by Chaichara

[Naam]

My pool is 1.5 year old. It is rather large 6m x 12m concrete pool tiled up with 10x10cm blue tiles. The pool has "infinity edge" on one side and the balast tank below it. It is a salt water pool but I doubt that this make any difference here.

Since it's conception I have noticed the water dissapearing from it. My builder didn't want to know and suggested that water dissapears due to vaporation. Strangelly enough it happens irregardles of cloudy or sunny days. Even more strange is fact that the salt level also constantly goes down which I belive is due to the fact that the pool leaks and I have to add fresh water to it all the time. How much? About 200 liters a day!

= normal evaporation which happens especially during the present cool months at night when the ambient temperature is lower than the temperature of the pool water. the same applies (to a lesser extent) for the summer months. night temperatures are mostly lower than water temperatures. in fact i think that for a 72m² pool an evaporation of only 200 liters a day is quite low.

[LaoPo]

My pool is 1.5 year old. It is rather large 6m x 12m concrete pool tiled up with 10x10cm blue tiles. The pool has "infinity edge" on one side and the balast tank below it. It is a salt water pool but I doubt that this make any difference here.

Since it's conception I have noticed the water dissapearing from it. My builder didn't want to know and suggested that water dissapears due to vaporation. Strangelly enough it happens irregardles of cloudy or sunny days. Even more strange is fact that the salt level also constantly goes down which I belive is due to the fact that the pool leaks and I have to add fresh water to it all the time. How much? About 200 liters a day!

= normal evaporation which happens especially during the present cool months at night when the ambient temperature is lower than the temperature of the pool water. the same applies (to a lesser extent) for the summer months. night temperatures are mostly lower than water temperatures. in fact i think that for a 72m² pool an evaporation of only 200 liters a day is quite low.

I didn't know it could be that much.

Would a roll-up "blanket" stop evaporation ? Roll out at night would stop evaporation considerably, wouldn't it ?

http://www.directpoolsupplies.com.au/webcontent22.htm just an example but there are electrical ones as well.

LaoPo

[notime]

Thank you very much for the replies so far. Although I'm pretty sure my builder, who were the "proper swimming pool company with 15 years experience" may be guilty of ALL of these:

- No waterproofing agent in the concrete. hairline cracks i the concrete from being allowed to 'dry' in the hot sun rather than being kept damp and allowed to cure slowly.

- Non use of rubber 'water-stop'

- Non use of special water-barrier tile adhesive.

- Insufficient sealing around the underwater light conduit, maindrains, water nozzles, and anything else that goes through the floor and walls.

I have also some hope that my leak is just a a product of my imagination. To start with I calculated it at 500 litres per day but now is seems to be at around 200l. The builder claimed right from the begining there was no leak and walked out of the job so they are not likely to do anything on the pool without a court order. I rectified some problems with it by myself like the insuficient sealing around the lights and wrong position of the one-way valve in the piping.

One more question: if I was to re-grout the tiles where and what grout do I use? Is there one especially made for pools or do I just add some water-repelling substance to it?

[neverdie]

Its called the 'Pan Evaporation Rate'.

There's some good stuff on the internet about this, you will actually be surprised how much water evaporates from your pool. There is a formula provided on some of these sites. I beleive the Pan Evaporation Rate for North-east Thailand is 1500+mm....It probably similar for Samui....I will see if I can find the info for you and report back.

Also the salt in your pool is NOT evaporating....Salt doesnt do that but there is another reason your salt levels are changing in the pool.

Basically The salt water chlorinator contains a salt cell. The gentle saline water is sanitized through a special process called electrolysis. The salt makes the water conductive so that electricity can pass between plates contained within the salt cell. As the water passes between the plates, electrolysis occurs, triggering a chemical reaction which releases chlorine from the salt. By adding small quantities of a granulated salt, a common chlorine is created. During the process, the chlorine is eventually converted back to salt. The electrolysis produces a very safe sanitiser known as hypochlorous acid (HOCl). This much weaker acid is the same sanitiser that is produced when you add pool chlorine to the water. It also activates other salts in the water to produce more sanitisers, without the negative effects of chlorine elements and chemicals associated with self-added pool chemicals

The salt does not become depleted so you only need to top it off a few times a year...depending on certain weather conditions. For Example, you will find that the salt levels in your pool are also affected by rain.

Also the amount of the water disappearing from the Pool will be greater than the Pan Evaporation Rate in WINDY areas.

Anyway, I will try to find a site for you.

Edited December 26, 2008 by neverdie

[neverdie]

Hey one other thing...BEFORE you go draining all your water out of your pool, you should note that you need to be very careful. It is actually possible to POP your pool out of the ground, this can happen to concrete pools & it will depend on the water table around the pool, ie: less likely to occur in sandy areas.

[neverdie]

Okay, now I remember a bit more.....the old mind isnt what it use to be.

If you want to get all freaky about this, there are mathematical formulas for measuring an exact rate for evaporation from your pool, however to get a good idea of what is going on @ your pool, you would have to take measurements over a period of time (to get an average). You could also try and find out the Pan Evaporation Rate for Samui & go off that as an indicator....using the formula & your known pool surface area of 72 metres square.

Having said all of that, The best way to find out how much your pool is evaporating on any given day or week is to do a BUCKET test. Get a bucket fill it to a point, mark that point on the bucket, place the bucket next to the pool ALSO mark your water level on the side of the pool. After one day, you can measure the amount of evaporation from the bucket and the pool....THEY SHOULD BE roughly the same, ie: if the bucket drops 2cm, then the pool should of dropped 2cm....even though a lot less water is gone from the bucket, it has a different surface area, so if 2cm goes from the bucket & 2cm from the pool then an educated guess will tell you in fact the pool is not leaking. 200 Litres is b#gger all for a big pool - how did you measure the 200 litres?

You should also consider, SPLASH OUT....ie: if you or the kids are bouncing in and out of the pool all day, plus if it gets windy, its probably more likely that you are going to lose more from the pool (given its surface area) and that of the bucket. Pick a non windy day to do the bucket test.

Edited December 26, 2008 by neverdie

[Chaichara]

What Neverdie says about 'popping' could be true if your water table is significantly higher than the floor of the pool (particuarly in Bankgkok), but only if your constructor did not think to include inexpensive hydrostatic valves in the main drains.

The main causes of salt loss are rainwater dilution if the water goes away to the overflow, and backwashing. Many pool owners tend to play too safe and overdo the backwashing. Backwashing is only generally neccessary when the pressure guage on the filter unit shows a marked increase, or when there is an obvious drop in the pressure of the water returning to the pool.

Many pool 'service' companies deliberately over-backwash in order to sell more chemicals or salt. Some pool firms in Pattaya charge 500 baht for a sack of sand. A normal non pool retailer will sell the same salt for less than half the price. 500 baht for a bag of salt may not sound a lot to many individuals, but multiply it by the number of bags the pool 'service' agent is selling to all his customers and you will understand why he runs a more expensive car than yours.

Nowadays, the trend is to replace filter sand with media such as Zellbrite or DiamondKleen that are much more performant than sand and last longer.