kris walker
Active Member
Hi everyone,
I am interested in understanding these different things. Everyone seems to know them except for me. And so I get confused in some of the conversation here. Based on what I've been taught in basic chem classes, and from what I've been researching the past 2 weeks, here is what I understand. Can some of you confirm this for me? Sorry it is long:
pH: measure of the amount of H+. In water, this is equivalent to measuring the amount of OH-. The range of the log scale typically found in nature ranges from 5 (acidic) to 9 (alkaline). Reef tank water should have pH of about 8.2-8.4. It is unitless.
Alkalinity: measure of the degree of "pH buffering". Water with high alkalinity is *not* the same as highly alkaline water. Water with high alkalinity does not fluctuate in pH very much because it is well buffered.
From what I have found, there appears to be no difference between "alkalinity" and measures of calcium. But I typical hear alkalinity values thrown around of "3.2". What scale does this 3.2 refer to? What units do the 3.2 have?
Calcium: it is not directly measured, but measured in terms of calcium carbonate with a "hardness" scale. Interestingly, the word "hardness" is based on the ability of
metal ions to react with soap to form a precipitate or soap scum. The range is from 0 (soft) to 300+ (hard). Units are in mg/l.
Carbonate hardness is *equal* to alkalinity.
I am pretty confident about my understanding of pH and hardness, but not so much about calcium. Are there specific measurement kits to measure calcium directly? If so, does the information obtained from the two different tests (carbonate hardness and calcium) always give the same answer?
sam
I am interested in understanding these different things. Everyone seems to know them except for me. And so I get confused in some of the conversation here. Based on what I've been taught in basic chem classes, and from what I've been researching the past 2 weeks, here is what I understand. Can some of you confirm this for me? Sorry it is long:
pH: measure of the amount of H+. In water, this is equivalent to measuring the amount of OH-. The range of the log scale typically found in nature ranges from 5 (acidic) to 9 (alkaline). Reef tank water should have pH of about 8.2-8.4. It is unitless.
Alkalinity: measure of the degree of "pH buffering". Water with high alkalinity is *not* the same as highly alkaline water. Water with high alkalinity does not fluctuate in pH very much because it is well buffered.
From what I have found, there appears to be no difference between "alkalinity" and measures of calcium. But I typical hear alkalinity values thrown around of "3.2". What scale does this 3.2 refer to? What units do the 3.2 have?
Calcium: it is not directly measured, but measured in terms of calcium carbonate with a "hardness" scale. Interestingly, the word "hardness" is based on the ability of
metal ions to react with soap to form a precipitate or soap scum. The range is from 0 (soft) to 300+ (hard). Units are in mg/l.
Carbonate hardness is *equal* to alkalinity.
I am pretty confident about my understanding of pH and hardness, but not so much about calcium. Are there specific measurement kits to measure calcium directly? If so, does the information obtained from the two different tests (carbonate hardness and calcium) always give the same answer?
sam
