pH, no you don't need a phd to manage it.
Managing pH is prepleing to many aquarists . It gets confusing particlarly when the relationship between pH and alkainity comes into the picture.Many try to manage pH wiht buffers a practice encourage by buffer manufacturer's but one tha leaves a tank wit hhigher alkainity and the same ole lowpH it had before the dosing in a short amount of time.
This from a post of mine on another thread addressing an experienced reefer's frustration about pH alk raltionships I hope it provides a frameworkd for those of you who wan't to control pH and maintain table alkainity but just can't get your head around the relationship. It seems like it took me much longer than it should have. Hope this makes it a little easier:
I wish I could go much deeper understanding the REAL relationship of Alk, Mg and Ca!! To me this is the hardest subject because there are so many variables and every one says one thing. I guess the differences between systems are a great deal when comes to really put the math on the paper. (a question from another thread)
Hi,
It's not as arcane as we tend to make it. This is my oversimplified version I hope it provides an understandable skeletal view of what's happening.
PH can be viewed most simply a measure of H+ in the water.
Pure water has a pH of about 7.0 ;lower ph means more acidity/ more H+ and vice versa.
Alkalinity is a measure of the capacity of the basic elements in the water to neutralize the H+/acidity.
Alkalinity is not a thing; it is a measure of many things .
Most of the alkalinity in seawater (96.5%) is bicarbonate/carbonate which is consumed by calcifying organisms( corals, mollusks, coraline algae, etc) . A biotic precipitation will also consume it via precipitation as calcium carbonate, when levels are high and pH is high. So, it needs to be replenished to meet consumption rates .
Magnesium slows down the growth of calcium carbonate crystals( precipitation) essentially stopping their growth,thus allowing more calcium and carbonate to remain in solution than without it.
So , if everything was constant it would be relatively simple. More alk which is basic equals higher pH and vice versa.
But it's not constant. There is a constant flow of mystery guests at the aquairum inn , all named CO2.
The aquarium lives in the air which effects the pH; the life inside it also affects ph and alkalinity.
CO2 equilibrates with the air around the tank; similarly the oceans and other bodies of water equilibrate with the atmosphere and its 400ppm CO2 as measured in May 2013.
CO2 is also produced and consumed by various organisms in the tank at various times
The speed of the equilibration (gas exchange ) depends largely on the surface area which is increased by agitation. it also depend ns on the level of CO2 in the surrounding air.
The CO2 level drives the pH in a real life aquarium ;not the alkalinity.
CO2 adds H+ by taking it from H2O as it hydrolizes in the water .When CO2 is reduced by gas exchange or biological acitivity like photsynthesis, the H+ is also reduced. Conversely, when CO2 in the water increases the H+ increases.
Calcium hydroxide(kalk) is unlike two part dosing or calcium reactor dosing both of which add carbonate for alkalinity.
Calcium hydrioxide(kalk) has no carbonate ; the hydroxide joins CO2 and makes carbonate CO3. It reduces CO2 in making carbonate alkalinity ; as a consequence of the CO2 use , the H+ is reduced raising the pH.
Since calcium hydroxide is dosed continuously, it keeps using CO2 in the water,ideally keeping pace with the flow of CO2 from the air and organisms. However, if too much is dosed at once it will use up too much CO2 and spike the pH and the rate of gas exchange won't provide enough new CO2 to keep up.
Ultimately, the higher levels of carbonate alkalinity calcium and pH in combination will lead to to precipitation of calcium carbonate.
This thread has more:
http://www.reefcentral.com/forums/showthread.php?t=2252982&highlight=ph+how+to+manage+it
For more still: try the articles on alkalinitity an ph by Randy Farely which are stickied at the top of the Reef Chemistry forum
Managing pH is prepleing to many aquarists . It gets confusing particlarly when the relationship between pH and alkainity comes into the picture.Many try to manage pH wiht buffers a practice encourage by buffer manufacturer's but one tha leaves a tank wit hhigher alkainity and the same ole lowpH it had before the dosing in a short amount of time.
This from a post of mine on another thread addressing an experienced reefer's frustration about pH alk raltionships I hope it provides a frameworkd for those of you who wan't to control pH and maintain table alkainity but just can't get your head around the relationship. It seems like it took me much longer than it should have. Hope this makes it a little easier:
I wish I could go much deeper understanding the REAL relationship of Alk, Mg and Ca!! To me this is the hardest subject because there are so many variables and every one says one thing. I guess the differences between systems are a great deal when comes to really put the math on the paper. (a question from another thread)
Hi,
It's not as arcane as we tend to make it. This is my oversimplified version I hope it provides an understandable skeletal view of what's happening.
PH can be viewed most simply a measure of H+ in the water.
Pure water has a pH of about 7.0 ;lower ph means more acidity/ more H+ and vice versa.
Alkalinity is a measure of the capacity of the basic elements in the water to neutralize the H+/acidity.
Alkalinity is not a thing; it is a measure of many things .
Most of the alkalinity in seawater (96.5%) is bicarbonate/carbonate which is consumed by calcifying organisms( corals, mollusks, coraline algae, etc) . A biotic precipitation will also consume it via precipitation as calcium carbonate, when levels are high and pH is high. So, it needs to be replenished to meet consumption rates .
Magnesium slows down the growth of calcium carbonate crystals( precipitation) essentially stopping their growth,thus allowing more calcium and carbonate to remain in solution than without it.
So , if everything was constant it would be relatively simple. More alk which is basic equals higher pH and vice versa.
But it's not constant. There is a constant flow of mystery guests at the aquairum inn , all named CO2.
The aquarium lives in the air which effects the pH; the life inside it also affects ph and alkalinity.
CO2 equilibrates with the air around the tank; similarly the oceans and other bodies of water equilibrate with the atmosphere and its 400ppm CO2 as measured in May 2013.
CO2 is also produced and consumed by various organisms in the tank at various times
The speed of the equilibration (gas exchange ) depends largely on the surface area which is increased by agitation. it also depend ns on the level of CO2 in the surrounding air.
The CO2 level drives the pH in a real life aquarium ;not the alkalinity.
CO2 adds H+ by taking it from H2O as it hydrolizes in the water .When CO2 is reduced by gas exchange or biological acitivity like photsynthesis, the H+ is also reduced. Conversely, when CO2 in the water increases the H+ increases.
Calcium hydroxide(kalk) is unlike two part dosing or calcium reactor dosing both of which add carbonate for alkalinity.
Calcium hydrioxide(kalk) has no carbonate ; the hydroxide joins CO2 and makes carbonate CO3. It reduces CO2 in making carbonate alkalinity ; as a consequence of the CO2 use , the H+ is reduced raising the pH.
Since calcium hydroxide is dosed continuously, it keeps using CO2 in the water,ideally keeping pace with the flow of CO2 from the air and organisms. However, if too much is dosed at once it will use up too much CO2 and spike the pH and the rate of gas exchange won't provide enough new CO2 to keep up.
Ultimately, the higher levels of carbonate alkalinity calcium and pH in combination will lead to to precipitation of calcium carbonate.
This thread has more:
http://www.reefcentral.com/forums/showthread.php?t=2252982&highlight=ph+how+to+manage+it
For more still: try the articles on alkalinitity an ph by Randy Farely which are stickied at the top of the Reef Chemistry forum
