The purpose of this article is to offer some explanation for some of the
current misconceptions about water parameters pertaining to the term General
Hardness or GH. It is unfortunate that a lot of UK koi hobbyists tend to
take general aquaculture knowledge, and apply it directly to Nishikigoi.
In so much as what is good for intensive aquaculture rearing techniques
for food
fishes are also good for Nishikigoi pond management.
The two aquatic cultures have entirely different objectives involved, in
what they set out to
achieve for the end result. Japanese breeders and universities are constantly
striving to perfect production, growth, and health aspects of Koi. It is
accepted that the Japanese are true masters and have made important discoveries
that link good koi health, excellent growth and superior
Hi development to many aspects of koi keeping, non more so than the subject
of Water
Hardness. The hobby would benefit greatly from attempting to learn from
the Japanese professional Nishikigoi industry.
It's all too common to hear some hobbyists say, Mains water in certain areas
is too soft, and
should be hardened. It's understandable that Carbonate Hardness (KH) should
be elevated,
but the same cannot be said for General Hardness. So the focus of this short
article is to offer some explanation as to why this need not be the case
in so many instances, and that indicators fromJapan suggest that Soft water
should be nurtured and taken advantage of, not necessarily hardened! It
is generally accepted in Japan by the Koi industry / breeders, that Koi
growth is enhanced in soft water. Hi will become thicker, the shine of the
skin (Tsuya) will improve,
and last but not least, the health of the koi will be stimulated and greatly
enhanced, hence less problems. But in a general sense the koi hobby tends
to believe that Koi are put into Japanese mud ponds because of the high
mineral content and low stocking levels will make the Koi potentially grow
larger at a faster rate than would otherwise be the case. Whilst there is
an element of truth in this statement, it does not show the full picture,
and can be interpreted
as a misunderstanding. The fact is many of Niigata's mud ponds have soil
that is so dead from
lack of minerals, that only rice (or Koi) can be grown there. However, mud
ponds do offer
benefits such as live insects, and plankton
KH Carbonate Hardness or Alkalinity.
Carbonate hardness is essential for the buffering effect it has on the pH
of water in a closed
circuit koi pond. If a recorded pH of a given volume of water is 8 and an
amount of acid is
added, it is commonly expected that the pH value should drop by the corresponding
amount of acid added, if there were little or no Kh value to the water,
this would be the case, but the
purpose of KH is to act as a buffer so rather than the acid added to the
pond directly
influencing the Ph value, the acid is spent on the carbonate ions in the
KH value and only
when the carbonate reserves of the kh value are used up will the acid directly
influence
and lower the ph. Hence, if the KH value falls too low, causing the pond
water pH to be
influenced too easily by everyday occurrences such as fish respiration,
fish urine, waste by-products from filtration system bacteria, plants life
and even acid rain, in short just about everything that is considered normal
in a pond environment that is capable of introducing
an acid base.
So by these examples it is easy to see why KH is so important. If a pond
has a low KH, and
regular pond maintenance isn't carried out, the water will lose it's buffering
capability, and
the pH will fall. At first this isn't a problem, as Koi are best suited
to a pH of 7.0. But, if left unattended, the pH will fall to dangerous levels,
and quickly crash the system. Resulting
in acidic water, and a pond full of either very unhappy or dead Koi, as
well as a dead filter. Example: A pond in an area where the water has a
typically low KH value This need not be a problem if the system falls into
the following criteria, I.E. the pH runs at a steady 7.0, and
pond maintenance is done religiously, perhaps at twice-weekly intervals.
The pond is not overstocked; feeding is done in constant measured amounts.
There is a good working
knowledge and you understand the pond system and how it functions, plus
the checking of
all water parameters are done at regular intervals, leave nothing to chance.
But, if non of the
afore mentioned criteria are present it would be the authors advice to keep
the pond water
KH well up and therefore well buffered, or disaster will strike! A good
KH level should be somewhere in the region of 2 to 6dH. There is no point
in running a higher level than 6,
as this will often result in a rise of the pH.
The Japanese consider a pH of between 6.8 and 7.4 to be ideal.
GH. General Hardness.
This is a measure of the amount of dissolved solids (mineral content), E.G.
calcium, iron, aluminium, manganese, magnesium, chlorides, etc. GH has nothing
directly to do with the KH buffering effects of water, also a GH measurement
is no indication of the KH value as the two
are totally separate independent readings. And the only thing they share
in common is the
term Hardness in the title name.
For Japanese Nishikigoi professionals, the ultimate goal is to achieve low
GH values.
GH can be measured as ppm or dH, (German Degrees Hardness) Many things can
effect Water hardness. A typical tap water reading in the Bristol area is
around 14dH (250ppm, or parts per million).
In Japan this would be considered high! However many more things can effect
and raise the
GH reading of a typical koi pond. Stocking levels, feeding levels, and chemicals
will raise
hardness.
This is one of the primary reasons that Koi are grown-on in mud ponds. Water
in a typical Japanese Mud pond, is generally between 35 and 85 ppm TDS.
The stocking rates employed
with most mud ponds are kept low so that the daily feeding doesn't raise
the water hardness.
It is thought by many, the main reason koi kept in Japanese mud ponds grow
very quickly. Concrete Koi ponds in Japan are often overstocked, and the
water is more likely to be in the region of 150 ppm TDS. This is the one
of the main reasons many Japanese hobbyists put
their best Koi back into mud ponds each year, they can then grow in soft
water, as opposed
to having their growth stunted with the harder water of a conventional Koi
pond, Plankton and micro organisms are another reason. TDS. Total Dissolved
Solids.
A TDS reading basically represents a combination of KH, GH, and any other
dissolved solids.
The readings below have been taken using a Japanese TDS meter. This meter
is sold in Japan
as a 'Water quality instrument'. From the TDS reading given below, we can
obviously assume
that a TDS reading of lets say 80ppm, that the KH might be for arguements
sake 2dH (36ppm), and hence the GH can therefore be a maximum of 2.45dH
(44ppm).
This is just an example to help you understand that in a given TDS reading,
a GH and KH in
total when combined, can't exceed the TDS reading, except when allowing
for the innacuracy of the test.
The following are pond water statistics compiled over the past three years
Bristol,
(pond 7800 gallons)
Mains water pH 7.5
Pond pH 7.4,
TDS 315ppm,
KH- 5dH (89ppm),
GH- 13dH (232ppm)
Pond number 2 of 4400-gallon,
TDS 310ppm.
Rain water 30ppm (TDS).
Swansea, Mains water pH 7.1,
Pond ph 6.9,
Mains water 50ppm (TDS),
Rainwater 25ppm (TDS), After allowing the stocking density to rise, the
pond now measures 154ppm TDS and it's thought that the reason for the
increase in TDS is because of overstocking/overloading, and major lack
of water changing. However, at 154ppm, the TDS level
of this pond is still far lower than average.
Japan, Mains water 75ppm,
Rainwater 3ppm,
Pond water (mud ponds) 35 to 108ppm (TDS)
Pond water (hobbyists ponds) 108 to 220ppm (TDS)
SWANSEA POND The pond study case in Swansea contains only 2500 gallons
of water.
The pond is heavily overstocked, but the filtration system is more than
capable.
And is born out by the following growth results, that were monitored very
closely.
Wakabayashi male Kohaku 47cm (2000) now 61cm (March 2002)
Wakabayashi male Kohaku 39cm (March 2000), now 55cm (March 2002)
Takumi Nisai female Showa, 35cm in November 2000, now 46.5cm (March 2002)
Kumonryu (Nisai, 25cm, April 2001), now 42cm (March 2002)
Ochiba Shigure (Nisai, March 2000), now 47cm (March 2002)
Yamabuki Ogon Female (Sakai Hiroshima, Nisai in May 2001, 40cm), now 55cm
(March 2002) Dainichi Tosai Kohaku (April 2001, 23cm) This Kohaku was
exhibited at the BKKS National
2001, survived, and now measures 39cm (March 2002)
Wakabayashi female Sanke 37cm (2000), now 48cm (March 2002)
Sakai (Hiroshima Showa), Tosai in June 2000 at 27cm, now 53cm (March 2002)
Dainichi Showas X5. These Koi were between 20 and 25cm in when put into
Colin's pond in October 2001 (Tosai of May 2001), and now, one measures
33cm, three measure 40cm, and one measures 42cm (March 2002). Tancho Kohaku
(Nisai), of 18cm in September 2000, now 43cm (March 2002).
All of the above Koi were supplied by us, and in addition to these Koi,
there also reside several other Koi of various origins. One of them is
a Chagoi which I remember two years ago as being about 45cm, which now
measures some 68cm! So, as you can see, the stocking level of this
pond is pretty much outrageous!
A further point of interest is that the filter system used is a "RTF 3500",
which I have heard
some people criticise. Although the design of this filter system is a
little unorthodox, it works
very well indeed. Colin is now about to dismantle the pond, in order to
build a bigger one of
about 7000 gallons. The original filter will be retained, but fed from
one drain. A second drain
will feed into an additional set of RTF filters.
Many other Koi supplied have achieved similar growth rates. Also, other
Koi supplied and placed into similar water in the West Wales and the Welsh
Gower area, have achieved similar growth. BRISTOL POND
The Bristol pond case study is some 7800 imperial gallons. Despite being
run at similar temperatures, and similar feeding rates to the Swansea
case study, the Bristol pond cannot achieve the same growth rates. The
only Major difference that is apparent, between the two
ponds, is water hardness. The best growth rate to date from the Bristol
case study was a Koi growing from 37cm (April 2000) to 45cm (December
2000). Also, a Shiro Utsuri, growing from
34 cm (September 2000) to 45cm (May 2001).
These two koi were the only exceptions to the rule. And the normal growth
rates for the Bristol case study, other ponds in the area have achieved
similar growth but, generally typical growth rates for the higher TDS
readings in the Bristol area would be disappointing when compared to what
can be achieved in the areas where softer water is prevalent.
But there is no doubt that ponds in Bristol area with a lower GH have
growth rates better than those with a higher GH.
JAPAN
Typical Japanese case studies are as follows; these figures are for various
major Japanese
breeders mud ponds in the Hiroshima area. All of the readings are TDS
readings, and hence represent a total of GH and KH levels combined. A
'PPM' figure should be devided by 17.9 to obtain a dH reading.
Wakabayashi 65 to 78ppm,
Takumi 76 to 85ppm, Takigawa 105 to 108ppm,
Imai 35 to 48ppm,
Inoue 35 to 48ppm,
Momotaro 75 to 85ppm.
Naturally, all of these ponds have growth rates equal to but mainly greater
than the pond in Swansea! But, temperature in Japan also plays a large
part. Other points to remember Feeding raises GH, Fish waste raises GH,
Iron, salt, and calcium raise GH, High Nitrates raise GH.
Zeolite lowers hardness a little, as do Ion exchange resins.
If you really feel that you must raise GH / TDS levels, then overfeeding
is the fastest way to do
it! (not advised).
MOMOTARO KOI FARM Momotaro is certainly one of the top 5 breeders in Japan.
President Maeda (Mr Momotaro) feels anxious when growing Koi in mud ponds.
President Maeda, feels that once Koi are placed into mud ponds; things
are no longer in his control. Consequently, President Maeda is much happier
growing Koi in concrete ponds,
as the Koi can be carefully watched, and their growth and development
can be carefully
controlled.This is an area where Momotaro Koi Farm excels!
President Maeda has developed a new filtration media. This media has an
appearance of coral,
but is a man made material, which is baked at high temperature. This media
is used in his
filter systems, and also in multi level trickle filters. These trickle
filters obviously remove
Nitrates, but also lower hardness!
President Maeda say's that low water hardness and low Nitrates are of
the utmost importance
in the quest for maximum growth and good development in Koi. Using such
methods,
President Maeda has achieved the following Around 1997,
Momotaro managed to produce a Tosai Kohaku of 51cm! Despite such fast
growth, the Koi maintained wonderful quality.
He has also grown the first ONE METRE GO-SANKE!!! But, unfortunately,
the famous
1,000,000-yen prize did not exist! It was the monetary value placed upon
the prestige
of being the first person to grow a one-meter go-sanke.
JAPANESE OPINIONS
After asking several breeders in Japan about the topic of water hardness,
it was said by all,
that soft water is essential in order to grow large Koi, further, good
Hi quality, Teri (lustre)
and Tsuya (shine) is also considered to develop well in soft water.
But, the opposite is true for good white ground, requiring slightly harder
water conditions.
Mr Izeki of Izeki Products is quoted as saying that, he considers a water
GH value should
be as low as possible, also if GH measures 3 dH (51ppm) or over, it should
be lowered.
Mr Izeki achieves excellent, growths rates equal to mud pond growth rates
in his concrete
ponds by maintaining low GH values.
In the September of 1999 issue of "Nichirin", the ZNA Japanese Koi magazine
there is an
article entitled "Basic Koi Keeping" subtitle, Water Hardness. This article
was supervised by,
Dr Takeo Kuroki (Honorary Chairman of the ZNA), Mr Nobuo Takigawa (Chief
of the Keeping
Skills Bureau), and Professor Ken Sasaki (of Hiroshima Kokusai Gakuin
University).
(quote): "Hardness. Hardness is an indication of the amount of calcium
or magnesium;
the lower this is the better suited the water is to the raising of Nishikigoi.
A reading below
50ppm (2.92dh) is considered desirable. This degree of hardness is also
said to control the appearance of the Hi and the Sumi".
WATER HARNESS SHOCK When Koi are harvested and put into hard water, they
can
sometimes roll onto their sides. The Japanese professional refer to this
as Water Hardness
Shock. A transition from soft to hard water is believed to causes Koi
great discomfort and
stress; hence they may sit on the bottom and are often to be seen rolling
over on their sides. It usually takes about three days for the Koi to
adjust to the water hardness and behave normally. This can also happen
when Koi are sent from Japan to England, despite sometimes the water being
hardened in Japan prior to shipping, this effect can still be observed
from time to time, however, the Koi soon adjust. It is also accepted in
Japan that Koi are more resistant to disease and also heal at a faster
rate in softer water. Note: Water hardness shock does not occur in the
case of a Koi being moved from hard into soft water.
CONCLUSION
There are two routes to take with hardness levels in your pond.
HIGH GH LEVELS
Good white ground and sumi development, but poor growth rates. (Ideal
for those that are
hoping to show their Koi, or those that have less time to devote to pond
maintenance).
LOW GH LEVELS. High growth rates, deep and even Hi,
but weaker white skin, and slower Sumi development. Bear in mind however,
that just a few
weeks in hard water will improve the white skin ready for a Koi Show.
It would be preferable to definitely go for the latter approach, it could
be viewed as a waste of time and money to invest
in buying an expensive Koi, and then restrict it's growth an development.
From a personal
point, I have just purchased a water softener. This unit uses ion exchange
resins to remove
the GH ions, and substitute them for Sodium ions. In practice, this unit
will completely 'zero'
the GH, so it is essential to allow some water to bypass the unit in order
to obtain the desired
GH level.
Copyright © FEBRUARY, 2002, M Snaden, ALL RIGHTS RESERVED