Archive for January, 2010


January 29th, 2010

One of the projects we had on the list to do was a fishpond. I have always liked the idea of having a couple of fish, but always thought the fish fund-i’s go a bit overboard with all the complicated filters, UV sanitisers etc. I wanted a pond that would basically look after itself, but support a couple of fish which will get fed occasionally.

Another hassle with ponds is that in our hot and windy climate they always needing refilling due to losses through evaporation – sometimes you think you have sprung a sudden leak after a hot and windy day! This means you either need to keep filling it up – or rig up some fancy ball valve arrangement from the mains.

So here enters the ‘Green’ pond idea – keep it topped up with rainwater. Now I know what you going to say this has been done before, but I think I have found a novel solution of keeping it neat and contemporary. In fact I challenge you to figure out how its done in the next picture:

Hidden rain filler

Hidden rain filler - pond on the left

So here’s what I did – I used the same design as for my rainwater tanks and set the level of the grate to the same level as the water level I wanted in the pond. Connected it under the paving with piping and presto you have a pond which is filled each time it rains. Once the level reach’s the top of the grate, it simply overflows like the downpipe would have anyway. I then cut the bottom out of a clay pot and put this over the grate to hide it. Here is a sketch to illustrate:



The design of the pond is simple rectangle  1.2mx1.5m  – I made it deep so the water level could fluctuate between rainy periods, about 1m. It is constructed of a 220mm 2 layer brick wall with brickforce wire reinforcing every 3rd coarse. It was then plastered and left to cure for a few weeks (mainly because I was putting off the nasty fiberglass job). Once it was nicely cured and dry, I then gave it a coat of normal resin with a second coat of black flow-coat to finish off. Those who have fiberglassed before will be saying but what about the glass matting – well I looked at the pond – there were no cracks and I didn’t have enough matting. So I decided to take a chance and only use the resin – touch wood it seems to be working and as long as it doesn’t crack it should stay that way!

To keep the water clean I put a good 4 inch layer of stone at the bottom to act as an anaerobic zone and then planted it out with some Irises and a water Lilly. Finally a submersible pump circulates the  water through 3 nozzles in the back wall. I was amazed that with 6 fish – 2 goldfish and 4 Koi that although it did initially go murky, after about 4 weeks the water stabilized was crystal clear. It has stayed that way for 2 months now and the only maintenance is I have cleaned the sponge filter on the pump twice. I know the system is healthy as 2 frogs have produced about a million tad poles which seem quite happy as well.

Now for the clincher – we are in the middle of a drought – it is in fact illegal to fill your fish pond with a hose and to date I haven’t filled it once. Enjoy the pics!