View Full Version : Simple quesiton: dH
WinterWind
03-28-2005, 3:57 PM
I read a book that uses dH as carbonate hardness. On this forum, you guys use kH for carbonate hardness, right? So basically, is dH the same thing as kH?
And books say that hard water is more stable, they are referring to the gH, right? Does raising kH raise also the pH and or gH?
THanks.
dH = (German) degrees of hardness that are used to measure General and Carbonate hardness.
KH = Carbonate hardness (the carbonate and bicarbonate content)
GH = General hardness (dissolved calcium and magnesium salts)
Harder water carries a higher or alkaline reading or higher pH. If you increase the KH, the pH will increase, but it (the pH) is more stable and less apt to fluctuate due to the buffering effect of the higher KH.
WinterWind
03-28-2005, 6:31 PM
So do I need to buy a test kit for dH, KH, and GH seperately?
KH and dH don't measure the same things?
What are the most important ones to measure and keep track of in an aquarium?
Usually GH and KH are sold together as test kits. KH and dH are parts of the same thing. KH is Carbonate hardness and dH is the measurement of it in degrees. dH is also the measurement of GH in degrees or degrees of hardness. For example, the KH in my tank is 4 dH and the GH is 7 dh.
As for what is important, it depends on whether you want plants or not and what types of fish you keep. For example, KH tends to be more important in a planted tank, but GH and more so, pH is important for both a planted or strickly fish based tank. pH will matter with respect to the type of fish you keepl Some tolerate lower (Raspboras) or higher (Swordtails) level and range of pH levels, but you will find it stated on this board frequently that a stable pH is more beneficial than fluctuations in an attempt to reach the "perfect" pH.
Ammonia, Nitrites and Nitrates are important, but will vary depending on what stage of cycling your tank is in or if it is already established. Ammonia and Nitrites will be more important in a tank just beginning or early in the cycling process as the ammonia is turned into nitrites by the bacteria that forms over time. Subsequently, the nitrites are turned into nitrates as other bacteria forms to make that transformation as the cycling process proceeds. Eventually, in an established tank, you will find yourself focusing more on Nitrates than Nitrites and Ammonia.
WinterWind
03-28-2005, 9:58 PM
Thanks for the info!
So basically, dH and kH are the same but different degrees? If I have the dH value, I can ge the kH, and vice versa?
Kasakato
03-28-2005, 9:59 PM
No. You need two different tests. Degrees are different from ppm.
Sorry, but degrees and ppm are measuring the same thing. One degree of hardness (either GH or KH) is 17.86 ppm. You can convert degrees to ppm by multiplying by 17.86 ppm per degree. Or you can convert ppm to degerees by dividing ppm by 17.86. It does not matter which unit your test kit reads, as they are fully interchangable.
The tests for GH and KH are quite different chemically as they are measuring different things, but they both report as the equivalent of CaCO3, calcium carbonate.
WinterWind
03-29-2005, 9:52 PM
So kH and dH measure the same thing?
Can I use dH and kH interchangably?
Do dH and kH measure the same thing, but only in different units?
That is Geman terminology. In this country we refer to GH or KH, and those two are specific and not interchangable, even though they are measured using the same standard (CaCO3). If you want to use "dH" you will have to define what it means.
"Hardness" has multiple meanings. In the hobby litertature, references to "hard" and "soft" water are usually aimed at the fish's native water, not at tank conditions. It is important for breeding certain fish. Alkalinity or KH or carbonate hardness is far more meaningful and useful to hobbyists maintaining fishtanks but not necessarily breeding them.
WinterWind
03-30-2005, 12:38 AM
Oh, so dH is just the german term? dH can stand for either kH or gH but you have to state what it is first?
I don't know how the Germans really use it, I don't read German, sorry. But on these boards if someone used dH I would ask what they mean.
mcps95
04-06-2005, 2:52 PM
Winterwind,
Listen carefully. dH is a unit (like miles, kilometers, pounds, etc.) kH and GH are levels of various ions. Think of kH and GH as something like (but not the same as) the level of ammonia or nitrate in a tank. You measure the level of kH and GH.
So, you test for kH, which is measured in degrees of hardness (dH).
For instance, your kH test might give the results of 3 degrees of hardness (3 dH).
Get it?
mooman
04-06-2005, 3:16 PM
mcps95, bravo! I just read this thread, and can't believe you were the first one to use the magic word:
UNIT!!
dH is a unit used to describe your level of kH or your level of gH.
It's funny how simple concepts are sometimes hard to get accross in type.
carpguy
04-06-2005, 3:55 PM
dH is a unit used to describe your level of kH or your level of gH.
Maybe to simplify it just a little bit further…
A dH is a degree of Hardness (dH). 1 degree hardness is the same as 17.8 ppm (parts per million) of hardness.
GH and KH are types of Hardness. GH is General Hardness. KH is Carbonate Hardness. They refer to different minerals in the water.
GH is a measure of the Calcium and magnesium in the water.
KH is a measure of the water's alkalinity, its ability to absorb acids without becoming more acidic itself.
Either type of Hardness can be measured in ppm (which is the same as mg/l) or in degrees of hardness.
If the GH test kit says 100ppm it could also be described as about 5.5 degrees GH.
If the KH test kit says 100ppm it could also be described as about 5.5 dKH.
Cup of water, cup of coffee.
WinterWind
04-06-2005, 8:08 PM
Oh, I get it!
So dH is a unit for measuring kH.
so like for example:
kH=3 dh
is gH also measured in dH?
mcps95
04-06-2005, 9:00 PM
Yes, dH is also a unit for measuring GH.
Sorry, but degrees and ppm are measuring the same thing. One degree of hardness (either GH or KH) is 17.86 ppm. You can convert degrees to ppm by multiplying by 17.86 ppm per degree. Or you can convert ppm to degerees by dividing ppm by 17.86. It does not matter which unit your test kit reads, as they are fully interchangable.
Use real units, so long as you specify what you are measuring. Either ppm or mg/l are preferable, but degrees KH or GH is acceptable - but the latter only if you specify which (KH or GH). If you just say dH, nobody will have any idea what you mean.
carpguy
04-06-2005, 11:19 PM
is gH also measured in dH?
Maybe its the abbreviations.
d=degree
H=hardness
GH=General Hardness
KH=Carbonate (but with a K) Hardness
There are two different types of Hardness that there are hobbyist test kits for and that get talked about. Either type of Hardness can be measured in mg/l (milligrams per liter), in ppm (parts per million) or in degrees of hardness.
Ppm and mg/l are always the same. They're just different ways of describing the same thing. Degrees are a different unit of measure equal to 17.86 of either of the other two. All three are units of measure.
Since there are different types of Hardness, dH (degrees Hardness) means about as much as Cup (unit of measure) of liquid. What kind of liquid? Cup of coffee? Cup of wheatgrass juice?
If you say degree of Hardness (dH) it doesn't describe what type of hardness. It'd be more descriptive to say degree of General Hardness (dGH) or degree of Carbonate Hardness (dKH). The unit of measure can be applied to either type of hardness.