Why Choosing the Right Pond Pump Can Save Lots of Money
Not all pond pumps are efficient in terms of electricity usage.
Over the last 10 years or so major improvements have been made to pond pump designs to reduce power consumption while still maintaining excellent performance. The cost of running a pump normally outweighs the purchase cost consideration. This is true yet few retailers will take this into account when selling a pump. I have used an extreme example below. However the principle applies to any pump purchase ... it is IMPORTANT to consider power consumption and not just the purchase price
 Sand Filters: Ugly, noisy, expensive to run, waste lots of water on backwashing, clog up with algae and are source of disease problems in ponds. They should not be used for ponds. |
Sand Filters Cost a Fortune to Run...The best illustration of how much money can be wasted in a pond environment is to take the case of a sand filter system using a swimming pool pump. I will use this example below. Here's the important point... any sandfilter needs a pump that can generate large flows at HIGH pressures in order to overcome the flow resistance caused by the tightly packed sand bed inside the sand filter. There is no other reason for such a large pump and large pumps consume massive amounts of power. In the vast majority of ponds a sand filter is totally unnecessary and can be easily and efficiently replaced with a gravity biofilter system. If you want any proof of this take a look at the filter systems used in other countries around the world ... South Africa is the only country using such large numbers of sand filters for ponds. The reasons are that sand filters are relatively cheap to buy, people are familiar with them through swimming pool installations, and electricity used to be cheap in our country. Now times have changed dramatically as you will see below. |
How to work out the annual cost of running a pump
A typical swimming pool pump used on sand filter systems consumes between 750 and 1100 watts of power (or 0.75 kW and 1.1 kW). A light bulb consumes between 0.06 and 0.1 kW).
The total power consumed by running the 750 watts pump 24/7/365 = 6,570
The total power consumed by running the 1100 watts pump 24/7/365 = 9,636
Now take a look at the costs of running these pumps at different electricity costs (unit cost per kWhr) and over a period of 1, 2 and 5 years. Refer to this link regarding Eskom charges ... the unit costs below do not take into account more significant tariff increases over the next 5 years which we all know will be enormous.
| Pump Size kWatts | Annual Power Consumption kW | Unit cost of electricity | R Cost 1 Year | R Cost 2 Years | R Cost 5 Years | |
| 0.75 | 6,570 | 0.40 | 2628 | 5256 | 13140 | |
| 1.1 | 9,636 | 0.40 | 3854 | 7708 | 19272 | |
| 0.75 | 6,570 | 0.50 | 3285 | 6570 | 16425 | |
| 1.1 | 9,636 | 0.50 | 4818 | 9636 | 24090 | |
| 0.75 | 6,570 | 0.60 | 3942 | 7884 | 19710 | |
| 1.1 | 9,636 | 0.60 | 5781 | 11563 | 28908 |
Now imagine if you could save 50% of these costs.. well you can. You need to consider doing the following if you have a sand filter:
1. Replace the sandfilter with a gravity flow biological filter
2. Replace the swimming pool pump by one or more submersible pumps consuming a fraction of the power. See pump curves here
Costs of Running Various Pumps
| Annual Cost to run pump at R0.50 cents per kWhr | ||
| Pump Wattage | kWatts per Year | Rands per Year |
| 20 | 175 | R 87.60 |
| 40 | 350 | R 175.20 |
| 60 | 526 | R 262.80 |
| 80 | 701 | R 350.40 |
| 100 | 876 | R 438.00 |
| 200 | 1,752 | R 876.00 |
| 300 | 2,628 | R 1,314.00 |
| 400 | 3,504 | R 1,752.00 |
| 500 | 4,380 | R 2,190.00 |
| 600 | 5,256 | R 2,628.00 |