urifiers  are  really  just  water
               filtration  systems.  They  are
called  purifiers  in  the  koi  and
aquarium  worlds  simply  to  make  the
discrimination between biological filters
and tap water filters easier.
     There  is  a  danger  in  using  the
word  ‘purifiers’  as  it  could  lead
fishkeepers    to    thinking    that
‘purifiers’ produce ‘pure’ water. They
don’t.  Which  is  just  as  well  as  ‘pure’
water kills fish.
     Purifiers are now seen as an essential
part  of  water  management  for  koi
ponds. Dependent upon purifier design
and  your  own  tap  water  they  can  have
good, bad or indifferent effects on your
koi health. Purifiers have to be chosen,
installed  and  used  with  care  to  ensure
your  koi  enjoy  the  pros  but  avoid
the cons.
     There are two words I actively dislike
linked to water purification: ‘pure’ and
‘removes’.  The  blanket  use  of  either
word can lead people to believe that all
of a substance is taken out of the water.
Purifiers, as koi keepers know them, just
don’t work like that.
     Purifiers  are  not  magical,  they  are  a
group  of  different  products,  which
reduce  some  substances,  ignore  others
and  in  some  cases  actively  add  wanted
or  unwanted  substances  to  the  treated
water.  They  do  not  all  adapt  water  in
the  same  way,  nor  are  they  all  suitable
for  all  water  treatment  purposes  on  all
types of tap water.  
     The aim of well-designed purifiers is
to reduce fish-harmful substances found
in  tap  and  other  waters  to  amounts,
which are ‘fish safe’. That means some
of  the  ‘reduced’  substances  are  left  in
the  ‘treated’  water.  Using  a  correctly
specified  purifier,  koi  essential  minerals
are  not  stripped  from  the  water  passed
through the purifier.
     Choices can be made when choosing
purifiers. A major choice is whether the
purifier  is  particularly  designed  for  fish
or whether it has been ‘borrowed’ from
another use and ‘adopted’ for fish. One
main difference is the purifier’s ability to
reduce metals.
Oh yes it does! All tap waters contain
metals.  Some  purifiers  ‘reduce’  heavy
metals,  these  are  aluminium,  copper,
iron, lead, manganese and zinc.
       Every  metal  is  found  in  two
different  forms  in  water.  Some  of  each
metal is in particles, i.e. bits and pieces.
The rest of it is dissolved.
O  C  T  O  B  E  R     2  0  0  0 1 7 W  A  T  E  R     Q  U  A  L  I  T  Y A  N  N     T  E  L  F  O  R  D Ins and Outs of Ann Telford takes some of the mystery out of water purifiers...    TAP WATER
Mains tap water can be completely safe
and ‘healthy’ for people to drink but the
water needs for koi and people are
different. Mr John Towler lost most of his
koi through ulceration and subsequent
bacterial invasion.
The tap water had too high values of iron
and was too soft for koi. By reducing the
iron and hardening the water Mr Towler
saved his last four koi. They are now very
fit and healthy as are the new fish he has
added to the same pond.
P CASE STUDY ONE Photos supplied John Towler