Water samples for metals testing should be collected from the tap serving the pond. one-off tests for the six main metals, hardness and
alkalinity  is  £35.00  +  VAT.  How  much  were  you
going to spend on a couple of medications which you
weren’t sure would solve the problem? Frequently
with  koi  keeping  it  is  far  cheaper  to  find  out  the
cause  of  the  problem  than  to  keep  throwing  in
medications on a ‘that may solve the problem and if
it doesn’t we’ll try something else’ basis. Apart from
avoiding stressing out the fish by bombarding them
with  an  unnecessary  chemical  cocktail.  Another
objection is often -‘Oh that’s far too complicated’. Is
it? A telephone call or two to a laboratory followed
by sending them a designated bottle of water is all
it takes. Much simpler than choosing a koi! ‘Can’t I
keep it simple by just getting the water tested for
one    metal?’  Not  if  you  really  want  to  protect
your koi. Why do you need to know all the metals?      When  you  see  a  published  figure  for  the  ‘safe’
level of a metal for fish, it means that during the
experiments only one metal was in the ‘fish’ water.
Metals have a synergistic effect. If more than one
metal is present in the water then the ‘safety’ level for  each  individual  metal  has  to  be  lowered.  The
‘synergy’ means that with mixed metals each metal
can potentially damage the fish at a lower level than
if  it  were  the  only  metal  in  the  water.  If  you
purchase a purifier, a suitable purifier will contain a
wide ranging medium i.e. it reduces all metals, the
medium cannot differentiate between the metals.      So, for instance, the medium is totally incapable
of deciding to ‘hit’ the copper and leave all the other
metals alone. Therefore all the metals will affect the
life  of  the  purification  medium.  The  more  metals
there are the shorter the life of the working ‘stuff’.
To give a “feel” for the different scenarios a purifier
(and fish) may face: If we look nationwide, a search
I undertook in 1995 covering a two year reporting
period showed the following metals variations. The
graph  is  not  definitive  and  should  be  seen  as
examples  only.   Some   of  these  examples  were
collated  from  reports  where  consumers  tapwater
was  outside  the  control  of  water  companies.  E.g.
private iron mains, houses with old lead piping etc.
Today,  using  the  same  area  reports,  it  could  be
possible  to  quote  different  examples  as  water
changes i.e. it is not consistent. Information Collated in 1995 on
‘Metals’ Variations in Tap Water . I mg/l (parts per million) = 1,000 m g/l (parts per billion)      With wide variations still found, NO purifier will
treat exactly the same amount of water wherever it
is installed. Thus, the only way to ensure you are
reducing metals to fish safe levels with a purifier is
to know exactly what metals are in the water and
the  total  amount  of  those  combined  metals.  Then
using  that  information,  you  need  to  know  how
much  water  the  purifier  will  treat  before  the
purification medium needs changing.      Can’t  be  bothered  with  all  that?  Too  much
hassle? To put it bluntly, then there is no point in
purchasing a purifier as you seriously risk wasting
your money and failing to protect your fish. Even
houses next door to each other can have different

Substance           Minimums           Maximums
Aluminium         0 - 20 ppb            380 ppb
Copper               0 - 20 ppb            1,000 ppb
Iron                    0 - 20 ppb            1,600 ppb
Lead                   0. 10 ppb              1,000 ppb
Manganese         0 - 2 ppb               53 ppb
Zinc                   I - 2 ppb               270 ppb