I built a model river in my garden. Part II

By Stephen Rodgers

Wildlife Pond Section and a Simple Siphon ~5K GIF

The Wildlife Pond

So it was in early February that the first sod was turned. I was still researching the method of constructing the under-patio sump, and I have a thing about frogs, so the first body of water to be installed was the wildlife pool, or spring. This is really no more than a dish scooped in the soil to a depth of thirty or so centimetres, the hole was first lined with a lot of newspaper to protect the liner from sharp stones, then the liner was positioned and the pool partially filled to identify high or low spots. This water was then removed (by siphon), a 1cm layer of sand applied, followed by a 6cm layer of soil, fairly well compacted, then the pool was refilled. Over the next few weeks I added various oxygenating plants, snails, a couple of small token goldfish and a gallon of frog spawn - thereafter it was largely left to get on with it.

Siphon tip #1.

From showing my system as it developed to neighbours and family, it seems to me that our education system is failing many of us. Some people have difficulty understanding water flow in general, and siphons in particular, but siphons can be invaluable to aspirant river engineers. The rule is this: If level A is at all higher than level B, water will flow down a tube from A to B - PROVIDED THE TUBE IS KEPT FULL AT ALL TIMES.

Most of the time you do not even need to do any sucking, simply slowly sink the tube below level A, taking care not to allow any air locks. Then put your thumb over one end and, KEEPING THE OTHER END BELOW THE WATER AT ALL TIMES, take it to any point below level A. Remove your thumb and the water will flow, and keep flowing until level B EXACTLY equals level A (can be useful, that), or you run out of water, or air enters the pipe.

Materials tip #1.

Don't bother scouring around the house for newspaper as protection liner, you will never find enough. Go up to the local paper recycling station and take some out for once!

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