Transcript What is water quality?

WATER QUALITY
Presentation on
WATER QUALITY
Introduction
•
What is water quality?
•
Why is water quality important when keeping fish in captivity?
•
Name three different types of water habitats that fish might live in.
•
What is the nitrogen cycle?
•
How do you know how ‘clean’ and ‘safe’ the water in a fish tank is?
•
What does pH stand for?
Water Quality
What is water quality?
ANSWER
•
•
•
•
Water (H20) is made up of 2 hydrogen and 1 oxygen atoms.
Different elements contribute to the quality of water, depending on its
source.
The physical and chemical characteristics of water determine what kind of
life it can support.
These characteristics include things like: temperature, levels of toxic
substances, level of dissolved oxygen, pH etc.
Water Quality
Why is water quality important when keeping fish in captivity?
ANSWER
•
Inappropriate water quality can result in stress in captive species like fish.
•
Such stress can cause ill health, problems in fighting infection and
accessing oxygen available in the water.
Water Quality
Environmental Adaptions
•
When keeping fish species in captivity it is important that the water quality
best suited for the species is managed properly.
•
To do this you need to know what the species natural water habitat is.
•
The earth is a planet covered mainly by water and inhabited by a vast
number of species all of which have evolved specialist physiological
adaptions to survive the different water conditions that exist on the planet .
Water Quality
Water conditions
•
Earth although covered mostly by salt water, thanks to the planets water
cycle provides water habitats that range from fresh water
brackish
water
salt water of varying densities of salinity.
Water Quality
Temperature Zones
Water temperature in captivity relates directly to the temperature zone of the
planet that species inhabit in the wild.
NB:
•
•
Temperature varies with water depth and currents in the oceans.
Temperature also varies in rivers & lakes at high altitude and such
influences as melting ice caps.
Water Quality
Water Habitat Type
Captive species can be categorised
according to the type of water habitat
and temperature they originate from.
•
•
•
•
•
Cold freshwater e.g. goldfish,
stickleback, orf.
Tropical freshwater e.g. gourami,
neons,
Coldwater marine e.g. blenni,
Tropical marine e.g. yellow tang,
seahorses, etc
Brackish water or estuarine fish
e.g. archer fish, monos
Water Quality
Freshwater
•
Rain water falls as fresh water (i.e.
without salt) and joins streams
that feed rivers and enter lakes.
•
During this process it erodes the
surrounding land and dissolve
rocks and minerals such as
calcium and magnesium.
•
It is this dissolved mineral content
that changes the levels of water
hardness / softness
Water Quality
Marine
•
Marine refers to species living in a
salt water environment.
•
Different species originate from
regions with differing salt levels
contained in the water.
•
Maintaining the correct salt levels
in captivity is very important.
•
The amount of salt contained in
the water is measured and
monitored using a hydrometer.
Water Quality
Brackish Water
•
Where a river meets the sea the
freshwater becomes mixed with
sea water. E.g. mangrove
swamps, estuaries.
•
Species that live in these areas
have adapted to cope with these
conditions and are able to tolerate
a wide range of salt levels.
Water Quality
The Nitrogen Cycle
•
Fish produce waste that contaminates the water that they live in.
•
Dead and decaying organic waste produces poisonous ammonia ( NH3).
Ammonia ( NH3) is also produced by the breakdown of proteins in the fish
and is excreted through their gills.
•
The planet has a natural nitrogen cycle to help keep our waterways clean,
the same cycle takes place within a fish tank.
•
The poisonous (NH3) ammonia is converted to the not quite so poisonous
nitrite (NO2) by nitrosomonas bacteria
•
The poisonous nitrites (NO2) are converted to less harmful nitrates (NO3) by
nitrobacter bacteria.
To see the Nitrogen Cycle, view the animation in the water quality section.
Water Quality
Bacteria
It is very important when maintaining an aquarium to ensure that the important
bacteria:
•
•
Nitrosomonas and
Nitrobacter bacteria
… are present in sufficient quantities to cope with the volume of waste produced
by the fish population.
If there is too small a bacteria population the levels of poisonous chemicals i.e.
ammonia (NH3) and nitrites (NO2) will increase and kill the fish.
Water Quality
How do you know how ‘clean’ and ‘safe’ the water in a fish tank is?
Regular monitoring of these levels can be carried out using water quality test
kits.
A number of different test kits are available and usually give colour indicators of
the levels of such chemicals as:
•
•
•
•
Ammonia
Nitrites
Nitrates
pH
To see how to use these kits view the videos in the water quality section.
Water Quality
What might be happening if the ammonia levels are above zero?
ANSWER:
•
not enough nitrosomonas bacteria are present to convert the ammonia NH3
to nitrite NO2
Water Quality
What might be the problem if the nitrite level is very high but the ammonia
level is zero?
ANSWER
•
There are enough nitrosomonas bacteria to convert the ammonia NH3 to
nitrite NO2, but not enough nitrobactor bacteria to convert all the nitrite NO2
to Nitrate NO3.
Water Quality
Usually the test readings for an established tank are zero ammonia ( NH3),
zero nitrites ( NO2) and a small reading of nitrates (NO3) What does this
show us?
ANSWER
•
This shows that the nitrogen cycle is working and that there are large
enough populations of the right bacteria to convert the toxic ammonia (NH3)
to Nitrites (NO2), and convert the Nitrites (NO2) to the less toxic Nitrates
(NO3)
Water Quality
How do we reduce the level of the less toxic Nitrate(NO3) before it
builds up to dangerous levels?
ANSWER
•
•
In order to help reduce the levels of the less toxic nitrate, routine fortnightly
water changes of about 30% of the water should be carried out.
Partial water changes may also be needed if the tests indicate very high
levels of toxic chemicals NH3 & NO2.
NB
• Replacement tap water contains chorine which can strip the fish of their
protective mucous membrane and kills the bacteria needed for the nitrogen
cycle.
• To prevent this a dechlorinator should be used or water that has been left to
stand for 24 hours to allow the natural dissipation of chlorine.
Water Quality
Acid or Alkaline?
The number of hydrogen ions present in the water determine if it is acid or
alkaline. It is measured by the pondus hydrogenii (pH) scale.
0
1
2
most acid
•
•
•
3 4
5
6
7
8
neutral
9
10
11
12
13
14
most alkaline
Sudden changes in pH has a negative effect on fishes health.
Different species have different tolerance levels of pH depending on their
natural habitat.
Higher pH increases the toxicity of ammonia.(NH3)
Water Quality
Materials that upset water quality
•
•
•
•
•
•
•
•
•
•
Certain metals e.g. magnesium, copper, zinc
Some rocks e.g. soluble rocks, calcareous rocks, rocks with metallic ore
veins.
Over feeding
Over crowding of the fish population
Decaying matter
Poisons and pollutants drawn in from the atmosphere.
Badly maintained filters
Some pre – caste concrete decorations
Some Coloured gravel
pH
Water Quality
Do’s and Don’ts for Water Conditions
•
•
•
•
•
•
Don’t make sudden changes to water conditions.
When doing a regular change always use water of the correct composition
and temperature.
Don’t change fish from tank to tank unless the water conditions in each tank
are exactly the same
If rainwater is used as a source don’t collect it from a dirty roof or in metallic
containers.
Don’t let water anywhere near electrical equipment.
Don’t use saltwater to top up evaporation in marine aquariums use
freshwater instead, as salts aren’t lost during evaporation.