Natural Water Gardening
Gardeners with a natural pool are fortunate indeed. For water that has accumulated naturally and found its own level is invariably pleasing to the eye. Slight alterations can be made to suit one’s purpose, but generally the only improvements are those that come with skilful planting. Of course, with modern trends in housing and gardens we are less likely to come across a natural pond. However, there are those who abhor anything artificial and crave to construct a pool that is as natural as possible.
Before the introduction of plastics, polythene and fibreglass, pools were often made of puddled clay. Although not the most successful of structures, the technique by which they were built is worth relating.
The excavation having been completed, the walls and floor were dampened and then given a liberal coating of soot. This was a deterrent to worms who delighted in puncturing the clay finish. Very wet clay was then daubed like plaster over the entire pool surface, care being taken during construction to ensure that as work progressed the clay that had been puddled was kept damp. Occasionally spraying with water from a watering can with a fine rose attachment usually did the trick, although on large expanses a covering of wet hessian sacks was a much less laborious method of preventing drying.
Once completed, water was quickly run in and care taken to see that the finished level of the puddled clay coincided with the water surface. If any gap between ground and water level was exposed to the sun the clay would shrink and fall away. Thus on very warm days, even with an established pool, a hosepipe had to be kept at the ready to replace the water lost through evaporation.
This is however, an outmoded method of construction, but worth relating if only to acquaint the reader with the problems involved. Books and articles often recommend it as an economical way of building a pool. It may be economical in cash, but it is certainly not in time.
Those who prefer a natural-looking pool will be interested in asealant method of construction which has been in use in the United States for several years. Although the product itself is not yet freely available here, it does seem to present a useful alternative method and is worth looking out for in the future.
The sealant is an emulsified polymer which causes soil particles to bond together. It does not work on very sandy or stony soils, nor those that are exclusively peat. However, on barns, clays and those in between, it provides a simple method of reducing seepage by up to 95 per cent.
The pool is dug to the finished size and the soil packed as tight as possible with the back of a spade. Water is added until the pool is about half full. The sealant is then introduced and thoroughly mixed with the water. As more water is added stirring is continued to ensure thorough distribution.
It is important that the pool is kept full to the top during the sealing process. This will take twelve to twenty days. Any drop in the level of the water at this time will result in the exposed area not being sealed properly. During this process the water is milky and extremely toxic to. It takes three or four weeks to clear and become safe, but it is as well to test it first with one or two inexpensive goldfish.
Drying-out can cause problems with this kind of pool after sealing. Fortunately this can be alleviated by the use of a floating valve attached to an inlet pipe which will allow just sufficient water to enter. This could, of course, also be fitted to a puddled clay pool where the drying problem is more acute.
Few ideas that seem so simple and successful have no drawbacks at all and the soil sealant is no exception. Manufacturers recommend that algaecides and other chemical pond treatments should not be used as these can break down the seal. I also wonder what happens when the probing roots of aquatic plants ramify the walls or floor. These will surely cause seepage. The whole technique is new to us in Britain and we should perhaps not criticise it until we have gained more experience. It has certainly been used commercially for the construction of man-made lakes and lagoons in the United States for a number of years.