conditions, depth of house foundations, invert level of drains, position of fences etc. will also play a part in your final decision.

You cannot plan your pond in isolation - you have to think about the overall effect of the garden when everything is complete.

The most important factor will be your budget and therefore, when thinking of the size of your pond, you must consider the running cost.

The pond filters must run 24 hours a day, 365 days of the year. A mature filter will die very rapidly in a few hours if the water does not flow through and will turn toxic. This water must not then be allowed to return to the pond.

Let's talk about the basics, i.e. the pond and filters. Patios, decking, rockeries, paths, waterfalls etc. count for nothing if you cannot see your fish or the pond leaks.

Let's say you have decided on size and position, now you have to consider whether you want your pond level with the ground or raised above the ground.

The next thing to consider is how you will waterproof it:

1. Butyl/plastic etc. liner. 2. Fibreglass. 3. G4. 4. Pond paint. 5. Rein fibre.
Don't try to economise or cut corners here - use good known fish friendly materials. Some plastics and paints can be toxic or become toxic in use.

Fibreglass, rein fibre and liner give you a certain amount of flexibility in the construction of your base. The remainder give none. The concrete, brick or blockwork must be free from any form of movement, otherwise cracks or holes result in leaks. Therefore careful thought must be given to this stage. Another reason to look at size and budget. My No. 1 choice is fibreglass. Next shape the bottom of the pond down to the bottom drain. By doing so most of the "muck" will fall down to the bottom drain and find its way into the settlement chamber. A self-cleaning pond? Within reason. Remember that with the "muck out will go leaves, stale uneaten food and, in winter, heavy gasses, such as ammonia, 24 hours a day. Taking mid-water with the bottom drain going direct to waste is an alternative method of removing "muck". You than have to pull the drain - the rubbish sits there until you do. My choice is bottom drain to settlement.

How to I filter?

There are now so many different ways of filtration I suggest you ask other members for advice before embarking on your project or updating your pond.

1. A settlement chamber. This can be a round cone vortex.

2. A straight settlement chamber, i.e. a large box, or chamber filled with brushes or Springflow to mechanically catch the solids.