Page 70 - Koi Net - On-Line Koi Magazine - Issue 36

double stroke (compression and labour stroke) 2 litres of don’t run out right away to compare your pump
water is actually moved. It doesn’t matter what diameter specifications with these. I chose this graph because
is the pipe that’s connected to the pump. Let’s say you here the connection between head height, use in watts
can make 200 double beats per minute, you move 400 and the reached flow of the water (ideal conditions) is
litres of water per minute, or 24m³ per hour. The smaller together in one view. I didn’t measure them, but I’m
the diameter of the piping, the higher the pressure in the going to assume for this example that the manufacturer
piping work will be. But that 24m³ per hour stays. Such has done a good job.
pumps are always connected with safety valves, which
operate should the pressure become too high. In CHEAPER Suppose we take a pond of, for example, 15m³ and opt
addition, these pumps use a lot of energy, so totally PUMPS ARE A for a gravity filter so without (0cm) head height, then this
uneconomical for us in the Koi hobby. pump uses about 75 watts to pass the 15m³ every hour
SHORT TERM through the (submerged, chamber) filter.
Source: NVN Koi Basics, Dirk Zwagemakers.
SAVING AND However, if I want to use a smaller surface area of filter
Coming back to the general rule of thumb that you want and go up using a 2-metre-high trickle filter, then this
to have all the water from your entire pond circulate CAN RESULT same pump, which is built for this kind of pressure,
through your filter per hour. Look again at your pump, already uses 270 watts to give 15m³. About 200 watts
head height and length and cornering in your pipes. Will IN LONG TERM more to move the same amount of water, per hour.
THE DESIGN you get that? Even without actually measuring it, the EXTRA COSTS Times 24, times 365 = 1752kW. With the average total
answer will often be no. The design of the pump makes cost (in the Netherlands) of about 22 cents per kW, it
OF THE PUMP a lot of difference as it is explained above. For Koi costs an extra 385 euros per year. Quite roughly one
MAKES A ponds there are pumps that can move a lot of water if euro (or dollar) a day. If you put your trickle filter at
they don’t have a head height loss but can’t move a 1.5 metres height, which is often about the case then
LOT OF single water drop at 1 metre head height. Often these you are around 200 watts, 130 watts more which comes
pumps use the lowest wattage per m³. However, if you out at 68 cents per day due to the fact that you use your
DIFFERENCE go up with the head height loss, you also have trickle filter. That’s already the case with this terribly
specialised pumps for that which can build up a lot of efficient pump. With cheaper pumps, the difference will
pressure and get the water higher. It will cost more but be greater and result in extra costs.
with these pumps you still get a large amount of water
340
through your trickle filter, for example. If you use a
320
2-metre-high trickle filter, you will need a much larger Blue Eco 320
300
pump as with a trickle filter of 1.5 or 1 metre high, to get 280 5m
the same amount of water over it. 260
240
I will also come back in much more detail about these 220 Blue Eco 240 + 320
resistances in pipes and their lengths. For now, the 200
realisation that these affects take place is the most Power (W) 180 2m
important. Those choices with head height and type 160
of pump should be considered carefully for the 140
120
construction of your pond.
100
80 0m
Costs in Watts per Year
60
It is difficult to make a calculation in costs for all of you, 40
20
but in general there is something to be said using a
0
graph such as the one shown opposite of a pump 3 5 7 9 11 13 15 17 19 21 23 25
(Blue Eco model 240). This is not an average pump so
Flow (m³/h)
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