The process of green water and sickly fish elimination

Usually water loss is more a matter of the disappearance of the odd inch or two - in some cases intermittently. The result is that you find yourself regularly topping up with tap water, which feeds algae and irritates the fish. So you end up with green water and sickly fish you cannot see, or spending a fortune on chemicals to 'condition' the water.

Possible causes:

Evaporation

If it is a hot summer and the water loss is little more than an inch or two a week, the cause could very easily be evaporation. This is even more apparent when you have a new pool with perhaps a rock edge of fairly water absorbent stone that actually sits in the water. Some stone can act as quite an efficient wick for evaporation. A new unsealed, unpainted fountain ornament can have the same effect.

Fountain ornaments encourage evaporation by spreading and spraying water about everywhere including over themselves from which the water able to evaporate.

CURE:- If the cause is evaporation by wick effect then this generally cures itself as a 'verdigris' of algae and moss builds up on the stone. Folk in my part of the world speed up the process of 'weathering' by painting on a foul concoction of milk, cow muck and honey. Fountain ornaments that suck up the water can be sealed with a stone sealants or matt G4, epoxy varnish.

LINER LEAKS:- including concrete

Do you lose water only when the filter, waterfalls or fountain is running? If you do not know, try leaving it for a while with everything switched off and the pool just standing. If the water level still drops it is the pool liner. Do not despair. The cure is easy, it is the cause that can be the mystery.

The cause may reveal itself if you can bare to leave the pool leaking long enough to sink down to the level the hole is at. Then somewhere at that level there is the hole. If it was animal damage, it may often be restricted to the upper regions. In that case it may be possible to effect a repair without a total clean out and 'dryout'.

CAUSES:- To find the cause is the start to eliminate the problem for the future. It may be like one of the causes listed below or it can be a combination of more than one cause.

1) Liner age. All materials used for lining pools have a limited life expectancy. Apart from concrete, all the materials whether rubber or plastic, flexible or rigid, are affected by the ultra-violet rays in sunlight. Present technology is improving the ability to withstand this ageing process and many PVC and EPDM liners are given a lifetime guarantee against decay. But there are still a lot of old liners out there and you may have inherited one. Up until the mid-nineties most liner materials would age, and after some time, usually indicated by their guarantee, they would begin to crack up, particularly in exposed areas at and above the water level. That is the first place to look.

2) Things falling in, particularly rocks and animals. Look for rocks on the edge that might have tumbled in. It is animals trying to get out that can cause the problem. Labradors scrabbling on the side as they try to claw their way out, or as they emerge as a soggy mess they pull in a rock that topples to the bottom.

Children love things that make a BIG splash, like big rocks. They also love to break ice in the winter, usually with the most inappropriate tool they find in the garden shed, like the garden fork!

3) Wild life. Herons can stab holes in liners - accidentally. Geese and sometimes ducks can do terrible things to cheap, thin, liner material. They also work wonders with pool underlay that may be laid over a liner to protect it from a layer of subsoil to make it a natural conservationist style pool.

Moles and wood mice burrowing underneath can sometimes be inquisitive enough to investigate the edibility of this strange ballooning material that appears in their newly excavated burrow.

CLUES:- If a hole in the liner does not make itself apparent by letting the water level drop to the level of the leak, the pool must be cleaned out and the liner washed down thoroughly. Then let it dry out. Any holes should be immediately apparent as some of the water that has leaked out trickles back in. Even pinprick holes when the water that has leaked out returns back through the holes. If there is sand as an underlay to the liner, that will colour the water where it comes back through the holes. The holes are generally at a very exposed point or at the centre of an indentation, the indentation having been formed when a heavy object fell in.

Don't be satisfied with the discovery of just one hole particularly if it was small and the leak was substantial. Search diligently and methodically over the whole liner surface.

If there is no obvious cause of puncture:

First check the welded seams of the liner material. This is generally the 'Achilles heel' of newly installed liners. The temperatures that many of the liner materials will weld at are so specific that some manufacturers, in the hot pursuit of deadlines for stocking orders, have not been diligent enough in checking the welding equipment is up to the correct temperature before starting the day. Also in the early season rush, quality control seems to become an ideal rather than an actuality. I would always recommend checking every inch of the weld seams in a liner before you install it.

Clever remote top up systems, bottom drains and bottom fed filter systems where they meet and clamp onto liners are all areas to be suspicious of when the pool is full. When you consider that a mere 200 gallons of water is getting on for a ton in weight, then any sort 'add-on' to a pool liner is going to test out any inadequacies on the installation once it is full.

Weight is also a factor in raised pools without adequate footings and pools in made up ground. Here the ground can give way enough to distort and crack rigid and semi-rigid liners.

Still no holes? Check the folds particularly in the corners of very formal shaped pools, as these are sometimes not efficiently executed with liners that might only just be the right size. Also there can evolve a surprising amount of capillary action in the corners and minute siphons can get set up. It has happened to me on more than one occasion.