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Pond Construction

Planning a Pond

Building a Koi pond is not easy, but the rewards of having a well-constructed Koi pond are immeasurable.  As in any endeavor, success in building a Koi pond depends on careful planning and execution.  It can however be a humbling experience when you don’t know what you are doing. Even experienced Koi keepers will admit that if they can do it over again, they will do it differently

There was a programme on BBC a while ago where a group of people attempted to construct a Koi pond in a few days. This group consisted of experts on various disciplines and managed to convince the viewers that they have reached the deadline on time. A few weeks later they publicly admitted that the whole process was a disaster.

When potential hobbyists want to build a Koi pond, most of them are under the impression that you can do it on the spur of the moment and I have seen a lot of cases where they grab a spade and start digging without essential planning. Some of them succeed in ending up with a nice goldfish pond, while others end up with a nice hole in the garden. No water, no fish and very despondent. Another category of future hobbyists, end up with a pond that is not nearly suitable for Koi and eventually give up. The last handful of people is the ones getting advice from senior club members, they visit many ponds and also get assistance from professionals.

My advice is always, plan, plan and then plan again. Do not listen to advice from someone who knows someone with a Koi pond.

I will mainly concentrate on the construction of a concrete pond. To do the planning, the basic principles must be kept in mind and in this article I will try to demonstrate what planning needs to be done. Follow-up articles will also be published to explain how to eventually go about in constructing the pond that you have been dreaming about.

It is essential to do your homework about pond building. Building a Koi pond is an expensive exercise and when certain actions had commenced, it can only be remedied at great expense, if at all. Discuss your plans with experienced Koi keepers. Visit other ponds and ask every owner what he would do different next time. Read books, browse the Internet and if you still don’t feel up to it, rather get someone to either advise you or construct the pond for you. During the homework phase, get to grips with the basic principles of a Koi pond. It is the design that will determine how enjoyable your future Koi keeping experience will be. While doing your homework, consider what style of pond will blend in with your house or garden. Everyone has their own thoughts on what they want. South Africa as a country consists of various regions, sub-tropical, desert, winter rainfall and freezing winters on the Highveld. For the purpose of this article, smaller shallow ponds and ponds constructed of pond liners have not been considered. The position of the pond and the size and shape will inevitably depend on one another so you cannot really decide on one without the other. The order in which they are decided are not necessarily in the order shown below.

Where to build the pond
Deciding on the precise spot for the pond is sometimes hard because many factors will have an influence on the final decision. If possible, part of the pond should be in a sunny open position, but again this is not always possible.

Shape and style
The first thing to decide is if you want a formal or informal pond. This is where the homework that you have done will help you to come to a decision. Only you and your family can decide if the pond is to be the centre point of your garden and landscaped to suit, or if you prefer to have a pond built mainly to hold the fish and make general maintenance and access as easy as possible. In the end it is a compromise and each pond should be built to suit your personal tastes. Some prefer to have their pond level with the ground as this fits better into the landscape of the garden whilst others prefer to have it raised up by a couple of feet as it is easier to see the fish whilst sitting on the wall. The pond can be any shape, but for ease of building and especially for good water circulation, sharp curves should be avoided as much as possible.

Size of the pond
Consider your ultimate aim with the pond. The rule is normally, “Bigger is better”. A larger pond gives more room for growth and allow for more fish to be kept. A large water volume is also more forgiving when you medicate and the water parameters don’t change so suddenly. Most hobbyists would admit within the first year that they regret that they did not build a bigger pond. Also the cost of pond building gets less expensive per kiloliter as the size of the pond increases.

Depth of pond
It is generally agreed by all the books and experts on the subject that the pond should be between 1.5 and 2.4 meters deep. If, however you are building a much smaller pond then this depth may look completely out of proportion. The climate of the specific area should be considered, and the depth adjusted. The main argument in favour of a deeper pond is to prevent sudden temperature changes and extreme water temperatures during summer and winter.

Layout (slant) of the property
The slant of the property will definitely influence the design of the pond. It will further determine whether a gravity fed system can be installed or not. Believe me, it is a pain to empty filter media from a filter system while kneeling!

Underground services like electrical, water, sewer, irrigation and storm water services may either prohibit the construction of the pond, or it may increase the cost if it must be removed or re-routed. It is also convenient if the water mains as well as electricity are close by for filling the pond, effecting water changes and connecting all the electrical appliances that will be discussed at a later stage. Close proximity to sewer.

Another consideration is how close to the house you should build it. It must be remembered that with a six foot deep pond below ground then with the foundation and base the initial hole will be eight feet deep and especially if there is heavy rain then there is a danger of the sides collapsing and even undermining the foundations of the house itself. Long term planning of the house may also influence the position of the pond. Make sure that alterations to the house will not be hampered in future or worse, the pond may have to be sacrificed.

The local authority should also be contacted to determine whether building plans should be submitted.

Sunlight vs. Shade
Depending on the specific area in which you live, it is wise to know where there will be sun or shade during the different seasons. In Kwa-Zulu Natal a pond should get some shade during summer and many hobbyists resort to constructing some kind of protection against the sun. As mentioned elsewhere on this site, the chances of Koi getting sunburn are very slim, but the water temperatures get dangerously high in summer. In other areas it may be advisable for the pond to be in direct sun. Consider the matter and make an informed decision. Any pond should however receive natural daylight and a little bit of sun.

Koi can adapt to various circumstances but stress plays an important role in their well-being. Avoid places with excessive sudden movement, noise and vibrations of heavy vehicles

Visibility/ accessibility
The first idea is to place the pond near to the house so that you can see the fish even when it is a cold and windy day. This is ideal especially if you are able to put it close to the lounge or dining room patio door. In some cases this is not the best place and you may decide to put it further up the garden, but don't be disheartened as several Koi-keepers have their ponds at the top and or bottom of their garden and are quite happy with that arrangement. Others rue the decision to place the pond at a remote place and have installed an alarm system to alert them when the electricity supply to the pond is interrupted. I would recommend that the pond be positioned in such a way that you can see and appreciate these beautiful creatures when you leave the house. The more you observe the pond and fish the sooner problems are detected. Here in the North Coast, a knowledgeable hobbyist had a total wipe-out of his Koi population. His excuse- someone stole the pump and he did not notice it!

Storm water, rain water collection
Plan the pond in such a way that run-off water does not enter the pond during heavy rains, bringing with it all the lawn fertilizers, compost, manure and poisons into the pond. Some people collect rainwater in plastic tanks and effect the pond’s water changes with this collected rain water. In most areas of the country, rain water is slightly acidic with very little buffering capacity. Furthermore pollution accumulates on the roofs and during rainfall it is washed into the holding tank and ends up in the pond. I do not recommend this practice, but if it is important to you, test the PH of the holding facility frequently and also test for heavy metals.

Plants and trees
You should keep the pond away from large trees as the roots will seek out water and can damage the pond. Bamboo also has the same effect and will soon put down long roots that will easily penetrate a pond. Many of the plants we see in our gardens are poisonous and one should be very careful where they are planted. However one has to sometimes accept the inevitable and if your neighbour has a 40 foot Silver oak in his garden there is not much you can do about it. The ideal situation is to stay clear of large trees especially deciduous ones that will really create problems in autumn.

Some part of a garden may be planted with high maintenance plants that require frequent spraying with chemicals to rid them of aphids etc. Consider the types of plants and avoid a pond close to them or replace them.

Safety is another important consideration especially if you have young children. Your children may be grown up, but you have to consider you may have grandchildren. There is also the danger of children getting into the garden from next door. Children are very persistent when there is water around, and they cannot be watched all the time. Some bylaws require a pond or pool to be fenced.

Electrical points
It is a bonus if the pond can be constructed close to an electrical outlet. It will save some cost.

Water mains
If the water mains runs close to the pond site it will also save some cost. If you are lucky enough to have a borehole on the property, good for you but have it tested to determine the suitability for keeping Koi.

Soil conditions
The soil conditions will determine the eventual construction of the pond, especially the foundation, floor and backfill outside the pond walls. In areas where clay are encountered, it is better to build the pond on a “floating platform” that can move with the shrinking and expanding of the clay during wet or dry conditions.

Water table
If the water table in your area is high, it will be necessary to have additional space during construction where you can dig a drainage pit to assist in pumping the water away from the excavation.

Waste water runoff
It is also beneficial if the pond is constructed fairly close to the storm water drainage system. This is particularly important for the filter system that should be flushed on a regular basis. Believe me; it is nice to dispose of the filter sludge into the garden for the first few times until you get a call from the neighbours, or until your plants start dying off. Some plants cannot handle the pond waste, especially after you have salted the pond water.

Filter layout, hidden or under decking
When the pond site has been considered, remember to allow enough space for filter construction. The bigger, the better. Is there enough space where it can be hidden or will it be possible to conceal it below decking?

Last Updated on Saturday, 14 February 2009 23:07