Article 2 - Pond Pumps
Pump head or total dynamic head is the most misunderstood topic
among fish pond or Koi ponds owners. Most pond owners think their
pond pump head is between 5 and 7 feet. They are shocked when they
find out that it is actually between 20 and 40 feet. Matching a
pond pump to the pond pump head is vital, but seldom done.
If you buy a pond pump that is way too small it may only move a
trickle of water, or possibly none at all. One that is a bit larger
can still be too small to give good aeration, filtration and surface
skimming to your water garden, fish pond or Koi ponds.
Overloading a pond pump that is too small can
result in a shorter pond pump life, and more repairs. On the other
hand, choosing a pond pump that is too large will not only waste a
lot of money to run it, but can actually result in damage to the
plumbing and equipment.
In order to pick out the correct pond pump for your fish pond or
Koi ponds there are 5 steps you need to go through:
1. Determine the volume of your fish pond or Koi ponds;
2. Determine the flow you want based on the fish pond's or Koi
3. Determine the correct pipe size to move the flow you want;
4. Determine the water pressure needed to move the desired flow
rate through your system;
5. Determine the proper pond pump that will give you the desired
flow rate at the required pressure.
If your fish pond or Koi pond has a very irregular shape you may
want to back-calculate its volume by measuring changes in the salinity
when you add salt. There are some very good salinity test kits that
are extremely accurate. If you have a fish pond or Koi pond that
is under a few thousand gallons you may want to turn it over 2 to
3 times per hours. This is similar to large marine aquarium owners
who have learned to turn over their aquariums' water a minimum of
3 times per hour. If it is a larger fish pond or Koi pond you may
want to turn it over only once every 2 hours. The flow rate is very
important and determines the size of you piping and pond pump.
The pipe diameter has a huge effect on the pond pump head requirement.
Older systems may have algae, hard mineral scale, or muck build-up
on the piping walls, filters, strainers, valves, elbows, heat exchangers,
etc., making the published numbers way too low; and that is assuming
there are no rocks, gravel, or tree roots in the pipe. If any of
these things are present, then the smoothness coefficient is no
longer valid, and neither is the inside diameter of the pipe. In
other words, the Total Dynamic Head of the pond pump head can in
reality be much higher than calculated for new pipe.
Another way of determining the Total Dynamic Head is to measure
it, if your existing pond pump is working. You can install a flow
meter on each of the suction lines to help you balance the system,
plus a vacuum gauge on the suction side of the pond pump, and a
pressure gauge and another flow meter on the discharge side of the