Koi Ponds and Drought Situations





If you have a pond with a flushing standpipe chamber, sand filter or both it might be time to upgrade your system in times of drought as both of these use copious amounts of water.

Firstly change your system to a water and energy efficient system, e.g. filter and pond at the same level. Let’s say you have a 25,000 litre pond, this will need two bottom drains i.e. A 110mm pipe under gravity max flow rate 14,000 litres an hour, getting less, depending on number of bends and length of pipe run. Therefore 2 x 14,000 litres = 28,000 litres, less loss dependent on above but will give sufficient flow to turn the contents of the pond over every hour-every two hours is the minimum. These bottom drains are fed into a settlement chamber with a conical shared bottom called a vortex by some. The pipes must enter the vortex anti clock wise. Fit 110 ball valves so one can isolate the pond from filter the system. (See photo on next page).

These filters can be flushed using a minimum amount of water. To flush the bottom drains we fit a primary energy saving pump available from Oase or Resun. For the sake of this example let’s say we use a Resun P.G. 18,000 for the 24/7 pump. Electricity consumption is that of a large light bulb 230 watt which is a massive saving over a swimming pool pump. This pump can be used submerged or dry and they pay for themselves in electricity saving. In order to flush the bottom drains we need to increase the flow rate to maximum by fitting a second pump that pumps 10,000 litres an hour or 15,000 LPH throttling back with a ball valve to get max flow through the filter. This pump runs on a timer one hour in the morning and one hour in the evening. This additional pump has outlets near the floor of the pond which moves solids closer to the bottom drains. When running it increases the flow to maximum depositing the silt into the first vortex and thirdly exercises the fish by increasing the flow in the pond.

If you want more exercise, increase the running time on the second pump. The two pumps running together use a fraction of the electricity that is used by 4.45 kW swimming pool pump. Note these pumps move large amounts of water but do not have enough pressure to drive a sand filter. They will happily work with a bubble bead filter to remove the finer particles.

The above system is energy efficient, water wise and easy to maintain. Use the little water you need for flushing on the garden as it does wonders for plants.

If you have a system like the one described above or any other type of pond, one needs to install a tank of between 3 000 and 6 000 litres, depending on the space available.


Run your down pipes into this tank so if we are lucky enough to get some rain, we can collect the rain water to top up the pond.

Secondly increase the aeration in the pond to help maintain water quality and add bao-bio clear, a double recommended dose twice a week. This will help to maintain water quality as we don't do any regular ten percent water changes to conserve water.

To help keep the garden going, I recommend collecting your grey water from baths, showers and washing water, as well as the water you flush from pond or ponds. Fit a pressure sensitive pump and connect to your irrigation system or hose pipe.