Water Chemistry: pH, GH and KH What are they all?
-
Introduction :
The water chemistry requirements for
turtles are often underestimated. At the same time it needs to be
acknowledged that they are not fish and hence are not susceptible to
going belly up from a rapid pH change.
Some species do benefit from a more exacting regime, and it can be said that there are health benefits, even if indirect, from careful monitoring and adjustment of these water quality parameters.
First of all I will define these terms as I think we all probably have some knowledge of what pH means but some detailed knowledge is required.
Per Hydrogen (pH)
The pH of the water is a measure of
the balance between the Hydrogen (H+) and Hydroxide (OH) ions in the
water. I think most of us know that low pH is acidic and high pH is
alkaline or basic. Hence a pH of 5 is slightly acidic water, a pH of 7
is neutral and a pH of 8 is alkaline water.
For the budding chemists the equation is as follows:
pH = -log10[H3O+]
|
All right enough of the chemistry but
there is an important point here and any mathematicians will see it.
The pH scale is a logarithmic scale. In other words a pH of 6.0 is 10
times more acidic than a pH of 7.0 and a pH of 5.0 is 100 times more
acidic than a pH of 7.0. As a keeper you need to be aware that it is not
a difference of 1 when you go from 6.0 to 7.0.
Ways to lower pH
Filtering water over peat
Ways to raise the pHAdd bogwood to the tank Inject carbon dioxide CO2 Use a commercial acid buffer Water changes with softened water or RO (Reverse Osmosis) water
Aerate the water, driving off the carbon dioxide (CO2)
Filter over coral or limestone Add rocks containing limestone to the tank or use a coral sand substrate Use a commercial alkaline buffer |
Carbonate Hardness (KH)
This
is an area where many people get confused. One of the reasons the term
alkaline is avoided a bit and the term Basic is used for the pH scale is
because this reading is measuring the alkalinity of the water. It is
not the same as alkaline.
The
alkalinity is a measurement of the waters buffering ability, or its
ability to absorb and neutralise acid. Clearly the more alkalinity or
the higher the Carbonate Hardness of the water the less likely you will
incur pH swings in the water. It is therefore important to get this
figure reasonably high to stabilise the water.
Exactly
how high you want your dKH (degrees of KH) will depend on what pH you
choose to use. To people keeping fish from the African Lakes this is the
life and death of their fish. Those fish live in very stable high pH
conditions, they do not like change and the conditions can be difficult
to imitate. Fortunately turtles are not quite so sensitive. However, I
do think that basic fish keeping can teach the aquatic turtle keeper a
thing or two about water.
Ways to increase kH
Adding sodium bicarbonate (baking
soda). One teaspoon of baking soda added to 50 liters of water can
raise the kH of the water by approx 4 deg dH without a major affect on
pH.
Adding an air stone to increase surface turbulence driving off carbon dioxide (CO2) Adding commercially available products to increase buffering capacity |
Ways to lower kH
Injecting carbon dioxide (CO2)
Use reverse osmosis (RO) water. You can mix tap water with reverse osmosis water to achieve the desired kH. Adding commercially available products to decrease the buffering capacity. |
Do not use distilled water as it has
no dissolved salts and hence no buffering ability. Add a small amount of
acid (eg uric acid) and it will shift the pH very rapidly. It is also
highly osmotic and will react with the turtles renal system.
General Hardness (GH)
This
is essentially a measurement of Magnesium and Calcium ions in the
water. Again it is measured in the German degrees of hardness scale or
parts per million. This is what is generally meant by soft and hard
water which are terms people should be familiar with. The table below
shows comparisons between parts per million, the dH scale and the
generalised concepts of soft and hard water.
Ways to increase gH
Adding limestone to the aquarium (this will also increase kH which in turn will increase pH)
Adding calcium carbonate will raise gH and kH |
Ways to reduce gH
Adding peat moss to your filter
Use commercially available water softening pillows or a water softener (this removes calcium and magnesium ions and replaces them with sodium ions. Many people feels that this is an unacceptable method of softening water as many fish that prefer soft water don�t like sodium either. Mixing tap water with reverse osmosis (RO) water. |
General Hardness Table
|
||||
0 to 4 dH | 0 to 70 ppm | Very Soft | ||
4 to 8 dH | 70 to 140 ppm | Soft | ||
8 to 12 dH | 140 to 210 ppm | Medium Hard | ||
12 to 18 dH | 210 to 320 ppm | Fairly Hard | ||
18 to 30 dH | 320 to 530 ppm | Hard |
So what does this mean to the Turtle.
Here
is the complicated part, should you worry about the pH for a reptile. I
would argue yes you should and for a number of reasons.
1.
A stable pH environment is indicative of good water quality, a working
filtration system and can put you at ease that your turtles are in a
good healthy environment. A healthy environment generally means healthy
turtles. If the pH suddenly swings it tells you something is wrong,
before the turtle is sick.
2.
Aquatic turtles react osmotically with their environment via the
cloaca. By making this reaction in the turtles favour you increase the
efficiency of the water turnover in the turtle. I am not saying they
cannot live in variable conditions but if you have them in captivity why
not make them have a good healthy life.
3.
Many disease agents that affect turtles do best around neutral water.
As we are keeping turtles and not fungal spores why not have the water
conditions set to minimise the risks of infections.
Therefore I tend to recommend high pH conditions for turtles. Certainly Neutral
and above anyway. I do not think acidic conditions are particularly good for
turtles and they also seem to do better in moderately hard water, rather than
soft.
One
point must be made and that is that if you maintain the water above 7.6
pH then you need to have a good biological filter. This is because
Ammonia, which is toxic in itself, is converted to Ammonium at 7.6 and
Ammonium is extremely toxic.
Testing the Water.
This
is actually relatively simple. The commercially available aquarium pH
and Hardness test kits are certainly accurate enough. Follow the
directions on whichever ones you buy and do the tests once per week to
monitor the aquarium. Remember that when doing water changes you need to
prepare the water so that it�s the same as what you removed. So if you
add salt you need to add more. If you are maintaining a high pH and your
local water is soft and acidic you must correct this first.
For
the maintenance of high pH freshwater you should obtain a Marine pH
test kit as the freshwater ones usually only go up to 7.8.
No comments:
Post a Comment