Page 31 - Koi Net - On-Line Koi Magazine - Issue 53
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Flowrates and how important they are regarding also influenced by stocking densities and daily feeding
having a healthy pond and healthy Koi. quantities (protein levels), also.
But do we know what the differences are between So, is it the faster the Turnover rate, the better the
Turnover rate and Flowrates and why they are so water quality?
important? Must admit in the early years it took us a
while to understand the concept and even the ■ With ammonia the greater the number of times the
importance of these two essential functions to have a pond volume is moved through our bio-converter
healthy pond. To the fact we modified our return filters each day, the lower the ambient (average daily
pipework a few years back. background) ammonia level will be?
■ A higher Turnover rate will have the additional
To be fair you could describe the two functions in one
benefit of organic and inorganic solids, being
word, ‘Circulation’ as it’s critical that we circulate the
removed from our pond water faster. Consequently,
water; to introduce oxygen and increase the total
the water will be clearer?
dissolved oxygen content to all levels of the pond,
remove solids and chemical pollutants to our ■ Faster Turnover rates will bring the pond water
mechanical filters and bio-converter filters, and dilute ALL PONDS volume into contact with the atmosphere at a faster
TURNOVER ammonia. But, to break it down and go into Water rate than slow Turnover rates. Consequently, the
Circulation in more detail we look at how this water ARE DIFFERENT water will be degassed to the atmosphere and have
RATE IS movement is achieved, which is Turnover rates and TO CALCULATE the oxygen replenished at a faster rate. I agree with
DETERMINED Flowrates. TO FIND THAT this one especially with Bakki Showers.
BY POND So, what I understand is: SWEET SPOT! One important aspect that determines calculating the
VOLUME ■ Turnover rate is the number of times the TOTAL actual Turnover rate our pond systems can achieve are
the restrictions through frictional loss. This loss is
volume of our pond water is circulated through the
DIVIDED BY filtration system in a given time, which we usually through our filters and pipework, etc, which is why all
ponds are different to calculate to find that sweet spot!
PUMP SIZE express in number of times per hour.
■ Flowrate however, is the amount of water that flows This one may be of interest as there are two kinds of
friction in our Koi pond pipes, Skin Friction, and Form
in a given time through our pipework and filters,
Friction.
usually expressed in gallons or litres per hour.
(We use gallons being old school). ■ Skin Friction, this is the distance our water travels
through the pipes, pipework diameter as in smaller
So, Turnover rate is determined by the time it takes to
diameter more friction. The smoothness of internal
move the whole pond water volume through the
surfaces, etc.
filtration system and back into the pond. This rate is
important as it determines the speed at which various ■ Form Friction, this is the bends such as 90º elbows,
pond pollutants, ammonia is removed and the speed Filter beds such as restrictive media and the likes of
at which the regenerated water (oxygen rich and valves, etc.
pollutant free) is returned to the pond. Obviously, all
our ponds are different as the Turnover rate is So, Flowrate, is used to describe the volume of water
determined by pond volume divided by pump size passing through the filtration system of the pond in a
(capacity) but is influenced by our filtration, pipework given time, such as the movement of water through our
size, pipe length and various bends that cause pipes and filters, etc. Flowrate refers to the speed or
frictional loss. Calculating the required Turnover rate is velocity at which the water moves through the piping
and filtration system, by gravity and our pumps.
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