kh and stuff

[RockabillyChick]

what are these? i keep hearing people talk about kH and other levels, and i've never heard of them before coming to this site. i've only ever heard of Nitrites, Nitrates, pH, alkalinity, etc. etc. when talking about water perameters. from the way you guys talk about them, they seem important.....

 

[angelkitty]

Alkalinity = KH.

 

[RockabillyChick]

ooohhhh.......and thats acid/base, right?

 

[liv2padl]

Water hardness is measured in two ways. (a) the amount of calcium and magnesium salts in water. (b) the concentration of carbonate in your water. GH refers to the calcium and/or magnesium side of the molecule (cations) ... it stands for "general hardness". KH refers to the carbonate side of the molecule (anion) and stands for carbonate hardness. the total molecule is Calcium Carbonate (or Magnesium carbnate) CaCO3 or MgCO3

Alkalinity is the concentration of bases dissolved in water and expressed as parts per million (ppm) or milligrams per litre (mg/L) Calcium carbonate (CaCO3). These bases are usually bicarbonates (HCO3-) and carbonates (CO3-), and, in rare instances, hydroxide (OH-) ions. These ions, called buffers, are important because they slow the rate at which the pH changes. The magnitude of change is determined by the water's buffering capacity or its ability to absorb acids and/or alkalis (base) and is an often overlooked, though extremely important component of pH balance in an aquarium.

Alkalinity is not the same as hardness. Calcium (Ca++) and Magnesium (Mg++) are primarily responsible for hardness. However, in most waters, alkalinity and hardness have similar values because the carbonates and bicarbonates responsible for total alkalinity are usually in the form of Calcium carbonate or Magnesium carbonate. However, waters with high total alkalinity are not always hard, since the carbonates can be in the form of Sodium or Potassium carbonate.

The equation below shows that carbonic acid (H2CO3) dissociates into hydrogen (H+) and bicarbonate (HCO3-) ions. The bicarbonate ions can further dissociate into hydrogen (H+) and carbonate (CO3-) ions. When acid (H+) is introduced into well-buffered water, carbonate ions react with the hydrogen ions to produce bicarbonate. Thus, although acid is added, no change in the overall pH occurs. Furthermore, bicarbonate ions act as an additional reservoir for hydrogen ions. The reactions outlined in the equation below are pH sensitive and shift to the right as pH increases.

H2O + CO2 <=> H2CO3 <=> H+ HCO3- <=> 2H+ + CO3

water + carbon dioxide <=> carbonic acid <=> hydrogen ion + bicarbonate <=> hydrogen + carbonate

The units used to measure alkalinity will depend on the test kit. Some use milliequivalents (meq/L), dKH (German Degrees), mg/L or parts per million (ppm). Meq/L stands for milliequivalents per litre. A milliequivalent is 0.001 of an Equivalent, which is the weight of substance that will react with one atomic weight of hydrogen.

For aquarium purposes, you can use the following conversion factors:
50 ppm (mg/L) = 1 meq/L = 2.8 dKH.

 

[liv2padl]

Alkalinity = KH.

no, alkalinity is NOT KH. Alkalinity is not the same as hardness. Calcium (Ca++) and Magnesium (Mg++) are primarily responsible for hardness. However, in most waters, alkalinity and hardness have similar values because the carbonates and bicarbonates responsible for total alkalinity are usually in the form of Calcium carbonate or Magnesium carbonate. However, waters with high total alkalinity are not always hard, since the carbonates can be in the form of Sodium or Potassium carbonate.

The equation below shows that carbonic acid (H2CO3) dissociates into hydrogen (H+) and bicarbonate (HCO3-) ions. The bicarbonate ions can further dissociate into hydrogen (H+) and carbonate (CO3-) ions. When acid (H+) is introduced into well-buffered water, carbonate ions react with the hydrogen ions to produce bicarbonate. Thus, although acid is added, no change in the overall pH occurs. Furthermore, bicarbonate ions act as an additional reservoir for hydrogen ions. The reactions outlined in the equation below are pH sensitive and shift to the right as pH increases.

H2O + CO2 <=> H2CO3 <=> H+ HCO3- <=> 2H+ + CO3

water + carbon dioxide <=> carbonic acid <=> hydrogen ion + bicarbonate <=> hydrogen + carbonate

The units used to measure alkalinity will depend on the test kit. Some use milliequivalents (meq/L), dKH (German Degrees), mg/L or parts per million (ppm). Meq/L stands for milliequivalents per litre. A milliequivalent is 0.001 of an Equivalent, which is the weight of substance that will react with one atomic weight of hydrogen.

 

[angelkitty]

no, alkalinity is NOT KH. Alkalinity is not the same as hardness. Calcium (Ca++) and Magnesium (Mg++) are primarily responsible for hardness. However, in most waters, alkalinity and hardness have similar values because the carbonates and bicarbonates responsible for total alkalinity are usually in the form of Calcium carbonate or Magnesium carbonate. However, waters with high total alkalinity are not always hard, since the carbonates can be in the form of Sodium or Potassium carbonate.

The equation below shows that carbonic acid (H2CO3) dissociates into hydrogen (H+) and bicarbonate (HCO3-) ions. The bicarbonate ions can further dissociate into hydrogen (H+) and carbonate (CO3-) ions. When acid (H+) is introduced into well-buffered water, carbonate ions react with the hydrogen ions to produce bicarbonate. Thus, although acid is added, no change in the overall pH occurs. Furthermore, bicarbonate ions act as an additional reservoir for hydrogen ions. The reactions outlined in the equation below are pH sensitive and shift to the right as pH increases.

H2O + CO2 <=> H2CO3 <=> H+ HCO3- <=> 2H+ + CO3

water + carbon dioxide <=> carbonic acid <=> hydrogen ion + bicarbonate <=> hydrogen + carbonate

The units used to measure alkalinity will depend on the test kit. Some use milliequivalents (meq/L), dKH (German Degrees), mg/L or parts per million (ppm). Meq/L stands for milliequivalents per litre. A milliequivalent is 0.001 of an Equivalent, which is the weight of substance that will react with one atomic weight of hydrogen.

Then why would it say "total alkalinity (KH) ppm - freshwater" on the comparison chart on my test strip bottle?

 

[liv2padl]

Then why would it say "total alkalinity (KH) ppm - freshwater" on the comparison chart on my test strip bottle?

because alkalinity is misunderstood by a great many folks who know nothing about chemistry. remember, just because you read it in a book or the label on your test kit package, doesn't necessarily make it correct.