The Case of the Recalcitrant Swimming Pool

I know two wonderful people who, seeking a place to relax in their later years, found a unique corner of paradise, a stunning spot that overlooks a green valley filled with coconut trees and beautifully sculptured rice fields.

They designed a beautiful house that fits beautifully into the landscape, hardly noticeable on its perch above the valley and with an infinity edge swimming pool built into a grassy knoll. There’s something magical isn’t there about architectural design when it blends into its natural setting?

The gentle twittering of the birds in the trees, the burble of the subak, the tinkle of a waterfall, the local canine alpha male tearing the throat out of some opportunist interloper that dared to sniff the rear end of his beloved. Ah the sweet sounds of paradise.

This is an idillic place, a place where one could relax and let the cares of the world drift off to some distant oblivion far far away…….

But it is well to remember that, in a house of the modern era, the cares of the world don’t much care for oblivion and have an unfortunate tendency to come back and, ever so assertively, sink their teeth into your buttocks.

And so it was that, after seven wonderful years of carefree coexistence at one (well perhaps two) with nature an unfortunate incident occurred which shattered the silence, strangled the serenity, pulverised the peace, trashed the tranquility and wrecked the wellness………. The swimming pool began to leak.

In spite of numerous vain attempts the problem was not going away. People came, they tried, they failed, they went. More and more people until they ran out of people willing to try to solve the problem, time went on and people simply wouldn’t turn up and phones would not be answered.

Ends of tethers had been reached long ago, pleading down telephones was as effective as feeding viagra to a sloth and hopes for a return to tranquility was giving way to wailing and the gnashing of teeth,  dogs were howling and dental bills were mounting.

My phone rang and having neither viagra nor a sloth to hand and having a fascination for tricky problems I decided we’d better take a look.

Now as it happens I have a very trusty right hand plumber, one of those people as rare as a gallinacious jungle fowl’s molars in Indonesia – a tradesman and, more than that, a man who really knows his onions (well – his chillies) and, as on many similar adventures in the past, we set off together to investigate the case of the recalcitrant swimming pool.

There was clearly a leak, the pool was losing far more water than mere evaporation could account for. There were no wet areas or signs of water emerging anywhere around the pool and no signs of visible cracks or other damage to the pool or its pipework. It was a mystery.

But there was a further problem. The pool chemical balance would fluctuate dramatically. Days would be spent getting the water in good condition and then suddenly it would all go durian shaped. There seemed to be no rhyme nor reason to it.

When faced with such a situation it is always best to use a systematic approach and apply a bit of logic. Be aware of the technical aspects involved and, most importantly, determine the root cause of the problem and avoid being distracted by the symptoms.

Swimming pool leaks can occur in any of the component parts, the balancing tank, the water delivery pipework to the pool, the water return from the pool (particularly in infinity edge overflow troughs), and the pool drain system. Common problems are broken pipes, leaks where pipes pass through the pool shell or cracks in the pool shell itself. Ground movement is a common cause of problems which in minor cases can shear off pipes and in more serious cases can crack the pool shell. Leaking pipes can usually be easily fixed (unless the leak is underneath the pool – tunnelling under a pool is not conducive to long life expectancy) whilest cracked pool shells suggest poor design and/or construction and can be difficult and expensive to repair.

Now we should also note that infinity edge pools have a balancing (or balance) tank, this is because pools lose water to evaporation and the balancing tank provides a buffer – a reserve supply of water to replenish any loss of water in the main pool and keep the water level up to the infinity edge and flowing over it. A balancing tank is a small tank separate from, and below the level of, the main pool. Balancing tanks usually have a water supply controlled with a ball or float valve so they can automatically refill themselves when necessary.

In the pool circulation system water runs from the pool into the balancing tank and from here it is pumped through a filtration system (and chlorination system if one is installed) and back to the pool.

Pools without an infinity edge do not need a balancing tank because it doesn’t matter if the water level drops a little. In this case water is pumped directly from the pool, through the filter and back to the pool.

Back to our recalcitrant pool. The pool, balancing tank and pipework were checked for signs of cracking, ground movement or water in the ground. Nothing was found.

This pool has a well designed water circulation system. A bypass for the balancing tank has been installed which means that, by turning a few taps on or off water can be pumped from a drain at the bottom of the pool directly to the pump, through the filter and back to the pool and this allows the balancing tank to be bypassed.

The bypass allowed us to isolate the balancing tank from the main pool and so determine which was leaking. Both the balancing tank and main pool were filled with water, all taps were closed to isolate the pipework and the system monitored. It quickly became obvious that all the water was being lost from the balancing tank.

At this stage our friend decided he would take it from there and we left instructions with his staff to empty the offending tank, clean it, dry it out, examine it for cracks or other leaks and seal it on the inside. A couple of days later Fred our carrier pigeon brought us the news that no cracks were found and the tank had been sealed.

Two weeks passed but then once again the phone rang and wails of dismay drew us back. The staff had failed to find the leak and the tank was still leaking.

My trusty tradesman was let loose on the job, he quickly found a rather well hidden leak behind a right angle bend in some untidy pipework in the bottom of the tank which, with the skills of an experienced plumber, was quickly sealed.

But what about the mysterious fluctuations in the water’s chemical balance? This was a very interesting question.

When the balancing tank was emptied it was found that there was a deep layer of sludge in the bottom which had collected over 7 years.

Water flowed from a 2 inch diameter pipe (yes in Indonesia they still use inches for water pipes) into the top of the tank. When the balancing tank was full the water would fall only 10 centimetres or so into deep water and the sludge was left undisturbed at the bottom. However, when the leaking tank was nearly empty, the water would fall a good meter into the surface of the water only a few centimetres above the layer of sludge.

(I do hope you are paying attention to all this vitally important information.)

The water level in the balancing tank would fall overnight then, in the morning when the circulation pump switched on, a sudden rush of water into the empty tank would stir up the sludge releasing a good dose of trapped pool chemicals that had settled in the sludge. This would be pumped directly into the main pool causing a sudden change to the chemical balance of the water.

Cleaning the sludge out of the tank solved the problem.

So, with the pool fixed, this left only one final issue to address. The mutt’s nuts were removed and he was left to wander the streets in confusion – he knew there was something he wanted to do but, for the life of him, he just couldn’t quite remember what it was. Tranquility was finally restored to some beautiful corner of paradise.

Phil Wilson

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