metals such as aluminium dioxide
or silver. They are not designed
to take water ‘clean’ enough for
ornamental fish.
Fish have particular needs. Just
because a product is called a ‘purifier’
or a substance is a purification
medium does not mean it is suitable
for koi.
Bi-metallic media are a group of
products, which work by ‘throwing
away’, in koi terms, huge amounts of
zinc and sometimes, large amounts of
copper as they collect other substances.
In ‘people’ terms they are fine and they
are superb products for such things as
the treatment
of water cooling towers
to prevent Legionnaires disease. They
have a side effect, which could be
seductive to koi keepers. The ‘discarded’
zinc and copper kills algae i.e. blanket
weed. But some blanket weeds are very
resistant and it can take large amounts
of zinc and copper to kill the koi-
O C T O B E R 2 0 0 0
1
9
W A T E R Q U A L I T Y
Mr Michael Van Neste lost many koi and
had a horrendous few years of koi health
problems. He discontinued controlling
blanketweed with high values of zinc and
copper. Some time later he now has a
healthy pond and thriving koi.
CASE STUDY THREE
Figure Two (below) contains a letter written by a highly professional filtration expert who
strongly recommends that koi keepers do not use bi-metallic media when treating water for
ornamental fish (e.g. koi). He emphasises that, if used, on-site testing and corrective
treatment must be undertaken individually for every single system. The letter was first
published in Aquarist & Pondkeeper in November 1996, Mr Burrluck gave permission to
reprint it in a series of articles I wrote for the BKKS Koi Times and this article. For the good
health of your koi, please take its contents to heart.
Dear Sir,
With reference to your article ‘Fishkeeping's Hidden Agendas’ (A&P August) and in
particular references to the use of bi-metallic media to remove or regress undesirable
elements, as a supplier of such media I would like to offer my comments for your review.
My job function brings me into contact with a whole host of water treatment applications
and the relevant solutions for industrial, commercial and domestic situations are wide
ranging. One type of treatment we currently market and distribute is a redox alloy media.
Before offering the use of this process media to an end user, a certain amount of
accurate information and integrity must be gathered to assist in planning of water
treatment systems for its use in cooling towers and other recirculatory systems, drinking
water improvement, dechlorination, iron, H2S and heavy metal reduction and control of
bacteria, algae and hard scale.
When considering the use of the process media it is important to understand that the
media works through REDOX principle (gaining and losing of electrons). Depending
upon certain applications this principle could lead to the re-deposit of ionic metals,
through the redox alloy media’s slight elution (release) of copper and zinc. In many
applications that are commercial, industrial or domestic, the elution has no consequence
to the system or the vast majority of people involved, however it could possibly be
detrimental to ornamental fish if there is no additional finite removal of these ionic metals
down to the considered fish safe levels required.
As a supplier of water treatment equipment and packages, we have a responsibility to
ensure that the end user requirements are met and that satisfactory water treatment is
achieved. Water supply quality is sometimes rather erratic and far greater accuracy for
removal of resident ‘contaminants’ is required for ornamental fish than in many other
water treatment areas.
Although field and lab testing results are available for the use of our process media,
when comparing the measured quantities of redeposited copper and zinc from redox
alloy media against published and accepted fish safe levels we feel, at this time, that the
promotion of our process media into the ornamental fish keeping market as a feasible
integral component of standardised water filtration systems is not a responsible act
without first establishing set parameters.
It may be possible to offer the use of our process media as part of a combination
filtration stage whereby adequate control and contact time for the treatment to take place
is achieved. Stage treatment would necessarily include the use of finite or corrective and
supplementary medias to remove eluted ionic metals from the treated water. Due to
inherent complexities of using redox alloy media this would be brought about by
exhaustive testing and on-site trials of managed systems in order to determine filtration
stage design for individual applications for the achievement of certifiable certification. By
undertaking corrective measures to remove ionic metal elutions on the treated water,
redox alloy media function for bacterial and algae control could be impeded.
I hope that the information will be of benefit to your readers in that it clarifies our position
in the market and the possible concerns of installing systems that incorporate bi-metallic
media using the redox alloy principle.
S. D. Burrluck,
Uni-Flo Services Ltd.,
Brough
E. Yorks. HU15 1YQ
FIGURE TWO
Do purifiers always treat the same
amount of water whatever tap water you
put through them? How do you tip toe
through the ‘purifier’ minefield? How can
you ensure you purchase koi protection
and don’t waste your money? Next
Month Photos
supplied Michael Van Neste
