Author: Dr. L.E. Freese
Is our tapwater dangerous to pond and aquarium
life?
It is very important to
maintain superior water condition in an aquarium or pond, as this is the
living environment of the fish. If the water is unsuitable, the fish
become stressed which leads to ill health or even death.
CHLORINE
Although chlorine is
considered safe for human consumption, it is deadly to fish.
The concentrations of chlorine in South African
waters vary from area to area, and therefore it is best to contact your
water supplier and ask them what they use to sanitise the water in your
area. The average concentrations of chlorine in the listed cities are as
follows:
Bloemfontein:
0,1-0,2 mg per litre
Cape Town:
0,1-0,4 mg per litre
Durban:
0,97 mg per litre
Johannesburg:
0,2-0,8 mg per litre
Pretoria: 0,1-0,3 mg per litre
These concentrations are very
dangerous to fish, as some scientists say that concentrations of as
little as 0,05 mg per litre are harmful. The chlorine causes damage to
the lining of the gills of the fish which in turn decreases the ability
of the fish to absorb oxygen. Chlorine kills the nitrifying bacteria
(good bacteria) in the bio-filters and after 3-5 days there is an
ammonia spike, which leads to ill health of the fish.
CHLORAMINE
Chloramine is added to water
instead of chlorine due to its stable nature and therefore stays in the
water for longer. Chloramine is not used in all the treated water and
therefore it is best to contact your water supplier for more details.
Chloramine is becoming more popular as a water treatment method in South
Africa. Chloramine is dangerous to fish in that it passes through the
membranes of the gills and into the blood stream where it binds with the
iron in the red blood cells. This prevents the blood from transporting
oxygen, which leads to lethargy and eventually death.
An important fact to note is
that chloramine is not
removed through reverse osmosis, as it is able to penetrate the
membrane. Chloramine breaks down into chlorine and ammonia.
Established bio-filters are
capable of removing the ammonia but in new systems, zeolites will have
to be used.
HEAVY METALS
Heavy metals enter tap water
in numerous ways: lead and copper piping, air and ground contamination
and metals that are in contact with the aquarium water itself (filter
pumps and metal piping).
Intoxication
of heavy metals in fish is not detected early, as the intoxication
occurs with the accumulation of heavy metals in the water and in the
tissues of the fish. Here they interfere with the physiological
processes of the organs. The fish’s health deteriorates and bacterial
or fungal infections are common.
When choosing which
dechlorinator or water conditioner to use, it is important that it
removes chlorine and chloramine, and neutralises heavy metals. Water
conditioners that contain additional ingredients that assist the mucous
layer and stimulate the healing process should be considered to be
superior as they protect the fish from infections. Some artificial
mucous coatings can cover the gills leading to a decrease in oxygen
absorption.
In general South African
tapwater is safe to use in ponds and aquariums provided that it is
treated appropriately.
May 2001
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