N.Design Studio

A Guide To Modern Koi Pond Construction

DESIGNING YOUR POND

Most of us will have started keeping cold water fish and then after seeing Koi at a Koi dealer or at a garden centre decided that this was the way to go regarding our fish keeping. Many of us will have started with a small, or not so small, ornamental pond with very little depth and usually many plants including water lilies. Maybe your pond looked like something like the one on this page. These are very ornamental and look nice in the general setting of the garden, but are totally unsuitable for the successful keeping of Koi.
There are many people that do successfully keep koi with other fish is this type of pond, and very successfully with plants and a small filter system, but this website deals with larger koi only ponds without plants and we are aiming for crystal clear water.

Let us assume that you are now intending to build this type of pond and these notes are intended to give some ideas and things to consider before you make a decision. In most cases when you first visit other koi-keeper's gardens you may see some of the larger installations but don't be put off by the cost and size of these. There are many smaller and very good set ups that have been built, and it is important to see as many ponds as you can before you decide on a design. This is a big advantage in belonging to a local club because then you can visit other members, and often a club has books in the library which shows photographs of various ponds. There are now quite a few photos of ponds appearing on home pages on the Internet. Let us now start looking at some of the things to consider before designing your pond. The position of the pond and the size and shape will inevitably depend on one another so you can not really decide on one without the other. The order in which they are decided are not necessarily in the order shown below.

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. You should keep the pond away from large trees as the roots especially in the case of species such as Weeping Willows will seek out water and can damage the pond especially in the case of pond liners. Bamboo also has the same effect and will soon put down long roots and will easily penetrate a pond liner.
Many of the plants we see in our gardens are poisonous and one should be very careful where they are planted. Euphorbia, Yew, and Laburnum come into this category. However one has to sometimes accept the inevitable and if your neighbour has a 40 foot Silver Birch in his garden there is not much you can do about it except remove the leaves and catkins regularly from your pond. Privet hedges are often suggested to keep the wind off the water surface of the pond, but on a windy day in the Autumn a lot of leaves will fall into the pond. If possible the pond should be in a sunny open position, but again this is not always possible.

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.
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. If you are building the pond close to the house then it is important to get professional advice from an architect or an experienced builder. Regulations would ensure that professional builders or swimming pool builders would use shuttering when digging as deep as this. There is always the danger of a cave in especially when digging out trenches.
When working in this area always ensure that there is someone above ground who can get assistance in case of an accident.

This photo shows the excavation for a six foot deep pond which will be completely below ground. Allowing for the one foot thick base the total depth of this hole is over seven feet. Note also the sump, and the pump which is used to drain off any rainwater, or seepage from the ground.

The first thing to decide is if you want a formal or informal pond. Again this where your research into all the various other ponds and photographs 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 when using a butyl liner sharp curves should be avoided as much as possible.

Everybody likes to make their pond as large as possible, but there are several things to take into account.
The larger the pond then the more maintenance and personal effort will be required to keep that pond in top condition for your fish. Then we have the cost, not only the initial cost of building the pond and the larger filter system required, but of running costs. Items where cost depends on the gallonage of the pond are : -

1. Electricity for larger pumps.
2. Cost of replacement pumps.
3. Chemicals including salt for Spring & Autumn treatments, or any other treatments you need to carry out.

It should also be borne in mind that with a large pond and presumably more fish it is much more difficult when you have problems and have to catch, check, and if necessary treat each fish. With a pond say more than 10ft wide and 6ft deep even with a long handled net it is not easy to catch the fish. On average a pond of about 6,000 gallons would seem an ideal size to manage successfully, but there again nobody is average.

See also Pond size in Questions & Answers.

It is generally agreed by all the books and experts on the subject that the pond should be six feet deep, and if you are building a large pond say 18ft x 12ft this is probably correct and looks right when completed. If, however you are building a much smaller pond then this depth does look completely out of proportion. In these cases it may be much better to have a pond say with a minimum depth of say 4ft 6ins with a depth of 5ft in way of the bottom drains. There are many successful ponds in our club with depths similar to this which have operated for many years successfully even in some very cold winters. There again the South Wales area is fairly mild compared with some other parts of the British Isles.

Basically one has to decide wether to build the pond with a liner or to build it with concrete blocks and then render it using fibromix and then say Q4, or render it and then coat with fibre glass. If using a liner then butyl is recommended as although it is more expensive it will last a long time. If your pond is a formal shape then you can purchase a box liner which will be made up to the correct shape for your pond, and as long as you have got your measurements correct then it will fit with a minimum of creases or folds. If buying a liner then it is worthwhile asking members who have recently purchased one for their recommendations and compare this with the quotes and specification you have.
There are possible dangers with using liners as the liners can be pierced by sharp instruments, but this rarely seems to be a problem that members have suffered. Beware with the quality of liners and buy only from reputable dealers as we have had problems in our club with liners that have been toxic to the fish.
It is always adviseble to wash out and clean the liners very carefully before stocking with fish. This also applies to Fibreglassed and rendered ponds. It is worthwhile filling the complete system without filter media and then circulating for a few days before emptying out, cleaning again and then refilling.

Fibreglass coating.

Fibreglass is a very difficult product to apply successfully and this should only be done by professionals. One would think that anyone that repaired or built fibreglass would be ideal people, but unless they have had experience of coating a pond it is better to employ someone that has.
Fibreglass as used for car bodies and boats is toxic to fish, and so to be able to use it for our ponds then it has to be neutralised and it is important that the operator is full aware of this and has completed other ponds. Check with previous customers to ensure they were fully satisfied. The biggest danger is when repairs are necessary, or when alterations are being made to the original coating. It is adviseable to discuss this with the original installer, if possible before proceeding.
The cost of coating a pond can vary considerably but since 1993 our members have got very competitive quotes from Mick Whitehall of Brierley Hill, near Birmingham. This man has done quite a few ponds especially in the Midlands and the final price was similar to the cost of a box liner. Fibreglass can be any colour but Black or British Racing Green is usually used.
When the coating is completed and has dried out ready for use it is worthwhile checking over all of the surface especially at the corners as there is often little sharp edges which could damage the fish and these should be smoothed off.

This is a big subject and is covered more fully later in these notes. Although the filter system is listed well down the list on the next pageit is necessary to decide on the type, size, and materials to be used before starting the building of the pond as it is all an integral part of the design. If you do not have the room for the filter system you want then it would be better to have a smaller pond.

It is important to know the exact gallonage of your system and most members do remember to do this. It is also a good idea to know the capacity of your pond and your filter system seperately. You may decide at some time to treat only your pond so then you will need to know the gallonage of the pond on its own.
The capacity of the pond is unlikely to change, but the filter capacity will change if you alter the media or change anything with the system so if you know the pond system on its own then you can easily check out the filter system again and you have an accurate gallonage for all or parts of your system.
It cannot be stressed too much how important it is to know the correct gallonage when using chemicals in your pond during treatments.

Whatever type of pond you have decided to build then a lot of materials will be required. If you work all this out and get a rough estimate then you should show this to a few builders merchants and enquire about a discount. You should be able to arrange this even though you will not be purchasing it all at one time due to lack of space. When you are ordering it is worth checking on the cost of delivery so that you can minimise on cost and not have a large truck with only a small load as cost is often calculated on below one ton and above one ton being considerably more. The cost of skips can vary considerably and it is worthwhile phoning around to get a quotation. A large pond will require at least six to nine skips assuming most of the soil is to disposed of.

When you have finally got some idea of your final layout then it is a good idea to start marking out on the ground so you can get some idea of actual size as it does not always look the same as it did when you made that rough sketch during the Winter months.
It is ideal to have a nice drawing all made to scale laid out on graph paper, but many cannot do that and many ponds are made from rough sketches or lines made on the ground itself.
It is important, however, to work out all the materials you require and then try to make up the general costs. Don't forget all the small items as well because these all add alarmingly to the final cost.