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General Hardness
- Thread starter Jun Xhu
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- co2 gh water parameter
Vandal Gardener
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Morning Jun,
I copied the paragraphs from the krib (http://www.thekrib.com/Plants/CO2/) as my science knowledge sketchy at best
Carbonate and General Hardness
Many beginners (and even advanced aquarists) get the different forms of ``water hardness'' confused. Here are two nice articles to help: detailed article that summarizes many of the details presented here, in a single concise manner, and a somewhat simpler one with a historical perspective on the units. See also A little article from the old FAQ. KH, or carbonate hardness refers to the concentration of carbonates, ie CaCO3. GH, or general hardness, refers to dissolved calcium and magnesium. In many cases, these values are similar, because the minerals in your water are dissolved calcium carbonate. In the context of fish liking hard vs. soft water, we speak of GH. However, in discussing CO2, we will be dealing with KH.
Before delving into CO2 proper (and alienating the rest of the aquaria audience), here are a few articles about buffering:
The CO2 content of your aquarium is important if you are growing plants (though check out a discussion on which plants need supplemental CO2, and which may actually do worse with it!). But CO2 is also of interest to the general aquarist because it is intimately related to the water's carbonate hardness (KH) and pH; dissolved carbonates will raise both KH and pH, while addition of CO2 will lower pH. Here are some charts showing the relationship between CO2, pH and KH, along with a discussion of the actual chemical reactions. You can read CO2 content indirectly by from the combined pH and KH readings, from a good test kit, or try this simple metering method.
A few plants are able to take in carbon directly from dissolved calcium carbonate (a procedure called biogenic decalcification by some). This procedure in turn may cause your pH to rise.
You can easily make your own carbonate buffer from common chemicals. You can use Calcium Chloride to increase GH without changing the alkalinity and pH. Some suggest you can use hydrochloric acid in extreme moderation to reduce the buffering capacity of your water (this article also discusses an empirical result of CO2 content vs. KH).
I copied the paragraphs from the krib (http://www.thekrib.com/Plants/CO2/) as my science knowledge sketchy at best
Carbonate and General Hardness
Many beginners (and even advanced aquarists) get the different forms of ``water hardness'' confused. Here are two nice articles to help: detailed article that summarizes many of the details presented here, in a single concise manner, and a somewhat simpler one with a historical perspective on the units. See also A little article from the old FAQ. KH, or carbonate hardness refers to the concentration of carbonates, ie CaCO3. GH, or general hardness, refers to dissolved calcium and magnesium. In many cases, these values are similar, because the minerals in your water are dissolved calcium carbonate. In the context of fish liking hard vs. soft water, we speak of GH. However, in discussing CO2, we will be dealing with KH.
Before delving into CO2 proper (and alienating the rest of the aquaria audience), here are a few articles about buffering:
- A discussion on Alkalinity vs. KH, two terms often used interchangably. This article also attempts to explain what happens what happens when you have two buffers (ie, phosphate and carbonate) at the same time.
- Debate on units (degrees vs. ppm).
- Conductivity and its relation to dissolved solids.
- How to make your own African Rift Lake Salts.
- An experiment by George Booth to measure Ca, Mg and CO3 uptake in a planted tank.
The CO2 content of your aquarium is important if you are growing plants (though check out a discussion on which plants need supplemental CO2, and which may actually do worse with it!). But CO2 is also of interest to the general aquarist because it is intimately related to the water's carbonate hardness (KH) and pH; dissolved carbonates will raise both KH and pH, while addition of CO2 will lower pH. Here are some charts showing the relationship between CO2, pH and KH, along with a discussion of the actual chemical reactions. You can read CO2 content indirectly by from the combined pH and KH readings, from a good test kit, or try this simple metering method.
A few plants are able to take in carbon directly from dissolved calcium carbonate (a procedure called biogenic decalcification by some). This procedure in turn may cause your pH to rise.
You can easily make your own carbonate buffer from common chemicals. You can use Calcium Chloride to increase GH without changing the alkalinity and pH. Some suggest you can use hydrochloric acid in extreme moderation to reduce the buffering capacity of your water (this article also discusses an empirical result of CO2 content vs. KH).
