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How do I raise my Alk levels
- Thread starter chase33
- Start date
To refine points 3 and 4 a bit.
At a pH = 8.20 (average ocean pH with today's level of CO2) the ratio of alkalinity:carbon is 1.13:1. There concentration of alkalinity is a bit higher than the concentration of carbon.
For a pH of 8.2 we need a 1.13 alk:carbon ratio. If the ratio is higher on the alkalinty side we raise pH. If it is higher on the carbon side we reduce pH. How much we change the pH of the tank depends on how much we change the alk:carbon ratio in the tank.
Kalk
2:0 alk:carbon ratio. Lots of kalk adds lots of alkalinity and no carbon, so we raise pH a lot.
Carbonate-based supplement (like baked baking soda).
2:1 alk:carbon ratio. Lots of this adds lots of alkalinity and some carbon. It raises the pH, but not as much as kalk.
Bicarbonate-based supplement (like baking soda).
1:1 alk:carbon ratio. Lots of this adds adds lots of alkalinity AND lots of carbon. Since the alk:carbon ratio is lower than for pH = 8.2 we lower pH, but not toooo much.
Calcium reactor effluent
0.8:1 alk:carbon ratio (or somewhere around there--depends on how much CO2 is in the water, and hence what the pH of the effluent is). Adds alkalinity and lots of carbon. It lowers the alk:carbon ratio in the tank so lowes pH.
Hopefully this is a little clearer. Let me know if it's still muddy.
cj
At a pH = 8.20 (average ocean pH with today's level of CO2) the ratio of alkalinity:carbon is 1.13:1. There concentration of alkalinity is a bit higher than the concentration of carbon.
For a pH of 8.2 we need a 1.13 alk:carbon ratio. If the ratio is higher on the alkalinty side we raise pH. If it is higher on the carbon side we reduce pH. How much we change the pH of the tank depends on how much we change the alk:carbon ratio in the tank.
Kalk
2:0 alk:carbon ratio. Lots of kalk adds lots of alkalinity and no carbon, so we raise pH a lot.
Carbonate-based supplement (like baked baking soda).
2:1 alk:carbon ratio. Lots of this adds lots of alkalinity and some carbon. It raises the pH, but not as much as kalk.
Bicarbonate-based supplement (like baking soda).
1:1 alk:carbon ratio. Lots of this adds adds lots of alkalinity AND lots of carbon. Since the alk:carbon ratio is lower than for pH = 8.2 we lower pH, but not toooo much.
Calcium reactor effluent
0.8:1 alk:carbon ratio (or somewhere around there--depends on how much CO2 is in the water, and hence what the pH of the effluent is). Adds alkalinity and lots of carbon. It lowers the alk:carbon ratio in the tank so lowes pH.
Hopefully this is a little clearer. Let me know if it's still muddy.
cj
Forgot to mention:
If we want to get an alk:carbon ratio that comes right out to pH = 8.2 (thus, no change in pH) we can mix bicarbonate and carbonate at about a 7:1 ratio.
Bicarboante is 1:1 and carbonate is 2:1. If we mix 7 parts bicarbonate to 1 part carbonate we get about a 1.13:1 ratio, which gives a pH = 8.2
If we want to get an alk:carbon ratio that comes right out to pH = 8.2 (thus, no change in pH) we can mix bicarbonate and carbonate at about a 7:1 ratio.
Bicarboante is 1:1 and carbonate is 2:1. If we mix 7 parts bicarbonate to 1 part carbonate we get about a 1.13:1 ratio, which gives a pH = 8.2
(well, 3 & 4 not so much
3. Like Baking Soda. 1 unit of the Bicarbonate, HCO3-, in BS will raise the Alk up 1 "unit" and the CO2 up 1 unit. So it is 1:1
4. Like Baked BS / Soda Ash / Washing Soda. 1 unit of Carbonate, CO3-- will raise the Alk up 2 units but only 1 unit of CO2 just like the BS. So it is 2:1
Since the Bicarbonate has 1 - and the Carbonate has 2 -, we say the one with 2 - or -- is twice as "powerful" as the one with 1 - or -
3. Like Baking Soda. 1 unit of the Bicarbonate, HCO3-, in BS will raise the Alk up 1 "unit" and the CO2 up 1 unit. So it is 1:1
4. Like Baked BS / Soda Ash / Washing Soda. 1 unit of Carbonate, CO3-- will raise the Alk up 2 units but only 1 unit of CO2 just like the BS. So it is 2:1
Since the Bicarbonate has 1 - and the Carbonate has 2 -, we say the one with 2 - or -- is twice as "powerful" as the one with 1 - or -
I think I understand your question, but let me know if I misinterpreted/this doesn't answer it.
All of these methods can end up providing the same alkalinity--that's the easy part. The more difficult part is manipulating the carbon so that we get the pH that we want. You could add tons of CO2 to seawater to drop the pH down to around 4 and dissolve a whole bunch of CaCO3 and dump this in the tank. This will provide alkalinity, but now we've got way too much carbon dissolved in the tank, dropping the pH. It will take a long time for all of this carbon to escape as CO2, and our tank pH is out of wack until this happens.
By the same token, we could add a whole bunch of kalk and get the right alkalinity, but now our tank has way too little carbon, rasing the pH. It will take a long time for the needed carbon to diffuse into the tank from the air, and our tank pH is out of wack until this happens.
So, the limiting factor for keeping pH from going too low is not being able to get rid of carbon (as CO2) fast enough. The limiting factor for keeping pH from going to high is not being able to add carbon (as CO2) fast enough.
We can aerate to get rid of CO2 faster if we need to get rid of carbon (if the air is low in CO2), but that only goes so fast.
We can dissolve CO2 into the tank water pretty darn fast to add carbon if we need to, and that can be done pretty fast. It is much easier to get CO2 INTO seawater than back out of sea water.
So, as a consequence of all of this, we could easily add a lot of kalk or carbonate pretty quickly if we were simultaneously adding CO2 to the tank. That can be done with a pH controller, though I'd be nervous about leaving the future of my tank up to whether a pH controller and solenoid on a CO2 regulator work correctly
A much better way to do this would be to keep track of pH when adding CO2/kalk simultaneously.
Now, if the pH does go quite high then we also increase the amount of carbon in the form CO3-- (carbonate). When there is more carbonate the rate of abiotic precipitation of calcium carbonate goes up. The same happens if we raise the alkalinity a lot, but keep the same pH (then all of the different kinds of carbon go up, including carbonate). This increased rate of precipitation, practically speaking, starts to limit the amount of carbonate we can keep in the water.
Chris
All of these methods can end up providing the same alkalinity--that's the easy part. The more difficult part is manipulating the carbon so that we get the pH that we want. You could add tons of CO2 to seawater to drop the pH down to around 4 and dissolve a whole bunch of CaCO3 and dump this in the tank. This will provide alkalinity, but now we've got way too much carbon dissolved in the tank, dropping the pH. It will take a long time for all of this carbon to escape as CO2, and our tank pH is out of wack until this happens.
By the same token, we could add a whole bunch of kalk and get the right alkalinity, but now our tank has way too little carbon, rasing the pH. It will take a long time for the needed carbon to diffuse into the tank from the air, and our tank pH is out of wack until this happens.
So, the limiting factor for keeping pH from going too low is not being able to get rid of carbon (as CO2) fast enough. The limiting factor for keeping pH from going to high is not being able to add carbon (as CO2) fast enough.
We can aerate to get rid of CO2 faster if we need to get rid of carbon (if the air is low in CO2), but that only goes so fast.
We can dissolve CO2 into the tank water pretty darn fast to add carbon if we need to, and that can be done pretty fast. It is much easier to get CO2 INTO seawater than back out of sea water.
So, as a consequence of all of this, we could easily add a lot of kalk or carbonate pretty quickly if we were simultaneously adding CO2 to the tank. That can be done with a pH controller, though I'd be nervous about leaving the future of my tank up to whether a pH controller and solenoid on a CO2 regulator work correctly
A much better way to do this would be to keep track of pH when adding CO2/kalk simultaneously.Now, if the pH does go quite high then we also increase the amount of carbon in the form CO3-- (carbonate). When there is more carbonate the rate of abiotic precipitation of calcium carbonate goes up. The same happens if we raise the alkalinity a lot, but keep the same pH (then all of the different kinds of carbon go up, including carbonate). This increased rate of precipitation, practically speaking, starts to limit the amount of carbonate we can keep in the water.
Chris
Thanks Chris,
Other than being a controlling factor in the ph, is carbon used in anyway by the coral, and therefore if we run to the high side of ph, does that impact coral growth.
I know some folks think pushing alk and ca up may help calcification, I was just wondering if the diminished carbon affects coral growth in anyway.
Other than being a controlling factor in the ph, is carbon used in anyway by the coral, and therefore if we run to the high side of ph, does that impact coral growth.
I know some folks think pushing alk and ca up may help calcification, I was just wondering if the diminished carbon affects coral growth in anyway.
Ok, I think I understand the question now :
Using a quick and dirty definition, the pH is the balance of the opposing forces of alkalnity UP and a CO2 DOWN. There's a bit more to it than that, but this is close enough for our purposes.
Now, most of the alkalinity in sea water is provided by 3 different ions. In standard sea water 89.8% of the alkalinity comes from HCO3-, 6.7% comes from CO3--, 2.9% comes from borate, and the tiny part leftover comes from all of the other bases (OH-, MgOH+, PO4---, etc.). So, most of the alkalinty (~96 - 97%) is provided by carbon species.
So, if we remove carbon (as CO2) we will maintain alkalinity but raise our pH. Some of our HCO3- loses an H+ and turns into more CO3--. As we increase the amount of CO3-- in the water we increase the rate of precipitation of CaCO3 which lowers the alkalinity and hence the pH starts to drop back down. If we remove more carbon then the pH goes back up as does the CO3--. More CaCO3 precipitates, reducing alkalinity, and the pH drops back down again. We can continue this until all of the alkalinity is gone. This process is more-or-less how you get things like stalactites and stalagmites in caves. In caves the process is driven by evaporation--evaporation increases the concentration of carbon in the water, causing CO2 to diffuse out, raising pH and causing CaCO3 to precipitate.
So, if the alkalinity is ok and the pH is ok, then by definition the amount of carbon is ok. If the alkalinity is ok but the carbon is low we will have a crazy high pH (= 12, 13, something like that) which would be very unstable and CaCO3 would precipitate out, removing alkalinity. The pH would then drop.
The only way to have too little carbon is if we simultaneously have high pH AND low alkalinity (which is possible, but the tank would be pretty mismanaged).
Having said all of that, corals and other calcifying critters probably don't have enough carbon at natural seawater levels to max out calcification. They most likely use bicarbonate or carbonate for calcifiction (and bicarbonate for photosynthesis). So, really what we want to do is increase the bicarbonte and/or carbonate concentration, but we probably don't want to mess with pH too much while doing this for a variety of reasons. The best way to do this is to increase the alkalinity but watch the pH to make sure it stays ok (neither too much nor too little carbon).
Chris
Using a quick and dirty definition, the pH is the balance of the opposing forces of alkalnity UP and a CO2 DOWN. There's a bit more to it than that, but this is close enough for our purposes.
Now, most of the alkalinity in sea water is provided by 3 different ions. In standard sea water 89.8% of the alkalinity comes from HCO3-, 6.7% comes from CO3--, 2.9% comes from borate, and the tiny part leftover comes from all of the other bases (OH-, MgOH+, PO4---, etc.). So, most of the alkalinty (~96 - 97%) is provided by carbon species.
So, if we remove carbon (as CO2) we will maintain alkalinity but raise our pH. Some of our HCO3- loses an H+ and turns into more CO3--. As we increase the amount of CO3-- in the water we increase the rate of precipitation of CaCO3 which lowers the alkalinity and hence the pH starts to drop back down. If we remove more carbon then the pH goes back up as does the CO3--. More CaCO3 precipitates, reducing alkalinity, and the pH drops back down again. We can continue this until all of the alkalinity is gone. This process is more-or-less how you get things like stalactites and stalagmites in caves. In caves the process is driven by evaporation--evaporation increases the concentration of carbon in the water, causing CO2 to diffuse out, raising pH and causing CaCO3 to precipitate.
So, if the alkalinity is ok and the pH is ok, then by definition the amount of carbon is ok. If the alkalinity is ok but the carbon is low we will have a crazy high pH (= 12, 13, something like that) which would be very unstable and CaCO3 would precipitate out, removing alkalinity. The pH would then drop.
The only way to have too little carbon is if we simultaneously have high pH AND low alkalinity (which is possible, but the tank would be pretty mismanaged).
Having said all of that, corals and other calcifying critters probably don't have enough carbon at natural seawater levels to max out calcification. They most likely use bicarbonate or carbonate for calcifiction (and bicarbonate for photosynthesis). So, really what we want to do is increase the bicarbonte and/or carbonate concentration, but we probably don't want to mess with pH too much while doing this for a variety of reasons. The best way to do this is to increase the alkalinity but watch the pH to make sure it stays ok (neither too much nor too little carbon).
Chris
And just to add on to that, there are some reasons to think that corals and other critters use bicarbonte for calcification and other reasons to think that they use CARBONATE.
For instance, if you keep the amount of carbon the same but raise alkalinity/pH (like by adding kalk) a lot of corals and other critters will calcify faster. If they are using carbonate, then really they don't care how much carbon there is in sea water, they care how much carbonate there is. Carbonate concentration is determined by the TCO2 (total amount of any kind of carbon) and pH. If there is more carbon at the same pH, we have more carbonate. If there is the same carbon at a higher pH there is more carbonate. If there is more carbon AND a higher pH, there is even more carbonate.
On the other hand, corals might use bicarbonate for calcification, not carbonate. If they do that, then they care about bicarbonate and not carbonate so more bicarbonate should be good for them. However, to increase the bicarbonate in seawater without lowering alkalinity we need to lower the pH by adding something like CO2. The animals might like the carbonate, but the lower pH might end up messing up other things so we get reduced calcification at low pH, even though they are "happier" about increased bicarbonate. If that is the case, the badness associated with low pH is worse than the goodness associated with higher bicarbonate.
On yet a third hand, even though most published work has shown that corals calcify slower at low pH and faster at high pH, this is not universally the case. There are a couple of published studies where it doesn't seem to make a difference and one where there is even a slight increase at low pH. I also have some unpublished data I'm working on that looks similar. A logical explanation here is that the corals are "happier" about an increase in bicarbonate than they are "unhappy" about a decrease in pH, so you get a net positive effect.
So, that's probably all as clear as mud, but it gets to your question. Corals don't necessarily care how much "carbon" there is in sea water, they just care about how much there is of whichever kind they use (unless of course they use all kinds of carbon equally--they probably don't). This will depend on the alkalinity and the pH.
Figuring out this mess is what I'm doing for my thesis research... oh boy :
cj
First line fixed by Phyl
For instance, if you keep the amount of carbon the same but raise alkalinity/pH (like by adding kalk) a lot of corals and other critters will calcify faster. If they are using carbonate, then really they don't care how much carbon there is in sea water, they care how much carbonate there is. Carbonate concentration is determined by the TCO2 (total amount of any kind of carbon) and pH. If there is more carbon at the same pH, we have more carbonate. If there is the same carbon at a higher pH there is more carbonate. If there is more carbon AND a higher pH, there is even more carbonate.
On the other hand, corals might use bicarbonate for calcification, not carbonate. If they do that, then they care about bicarbonate and not carbonate so more bicarbonate should be good for them. However, to increase the bicarbonate in seawater without lowering alkalinity we need to lower the pH by adding something like CO2. The animals might like the carbonate, but the lower pH might end up messing up other things so we get reduced calcification at low pH, even though they are "happier" about increased bicarbonate. If that is the case, the badness associated with low pH is worse than the goodness associated with higher bicarbonate.
On yet a third hand, even though most published work has shown that corals calcify slower at low pH and faster at high pH, this is not universally the case. There are a couple of published studies where it doesn't seem to make a difference and one where there is even a slight increase at low pH. I also have some unpublished data I'm working on that looks similar. A logical explanation here is that the corals are "happier" about an increase in bicarbonate than they are "unhappy" about a decrease in pH, so you get a net positive effect.
So, that's probably all as clear as mud, but it gets to your question. Corals don't necessarily care how much "carbon" there is in sea water, they just care about how much there is of whichever kind they use (unless of course they use all kinds of carbon equally
--they probably don't). This will depend on the alkalinity and the pH.Figuring out this mess is what I'm doing for my thesis research... oh boy :
cj
First line fixed by Phyl
Ack!
First sentence should read "bicarbonate for calcification and other reasont think that they use CARBONATE."
First sentence should read "bicarbonate for calcification and other reasont think that they use CARBONATE."
Yeah... Yeah.......
Usually I'm not too bad, but a lack of sleep sends my typing skills down the tubes. You'd think coffee would help, but just the opposite.
cj
p.s. I'm on too little sleep and coffee right now
Usually I'm not too bad, but a lack of sleep sends my typing skills down the tubes. You'd think coffee would help, but just the opposite.
cj
p.s. I'm on too little sleep and coffee right now
Nick, just to make it easier to relate to some of the stuff just mentioned in some of the previous posts, the baking soda you mentioned would be "Sodium bicarbonate" and the baked baking soda as you mentioned would be "Sodium carbonate". These would be related to the bicarbonate & carbonate mentioned above.
Carlo
PS man you guys covered a lot while I was gone.
Carlo
PS man you guys covered a lot while I was gone.
In case some of you guys don't know a couple of the new people who showed up in out thread.
Jose (JDieck) is the creator of the Reef Chemical Calculator. He and his calculator are even featured in the popular book The Reef Aquarium - Science, Art, and Technology by J. Charles Delbeek and Julian Sprung (pg 207).
http://home.comcast.net/~jdieck1/chem_calc3.html
Chris has an article or two.
The Nutrient Dynamics of Coral Reefs:
Part I, Biogeochemical Cycles
Chris Jury
Reefkeeping Magazine - August, 2006
http://reefkeeping.com/issues/2006-08/cj/index.php
The Nutrient Dynamics of Coral Reefs:
Part II, The Oceanic System
Chris Jury
Reefkeeping Magazine - October, 2006
http://reefkeeping.com/issues/2006-10/cj/index.php
The Nutrient Dynamics of Coral Reefs:
Part III, Land and Sea
Chris Jury
Reefkeeping Magazine - November, 2006
The Nutrient Dynamics of Coral Reefs:
Part IV, The Sky Above
Chris Jury
Reefkeeping Magazine - December, 2006
http://reefkeeping.com/issues/2006-12/cj/index.php
Jose (JDieck) is the creator of the Reef Chemical Calculator. He and his calculator are even featured in the popular book The Reef Aquarium - Science, Art, and Technology by J. Charles Delbeek and Julian Sprung (pg 207).
http://home.comcast.net/~jdieck1/chem_calc3.html
Chris has an article or two.
The Nutrient Dynamics of Coral Reefs:
Part I, Biogeochemical Cycles
Chris Jury
Reefkeeping Magazine - August, 2006
http://reefkeeping.com/issues/2006-08/cj/index.php
The Nutrient Dynamics of Coral Reefs:
Part II, The Oceanic System
Chris Jury
Reefkeeping Magazine - October, 2006
http://reefkeeping.com/issues/2006-10/cj/index.php
The Nutrient Dynamics of Coral Reefs:
Part III, Land and Sea
Chris Jury
Reefkeeping Magazine - November, 2006
The Nutrient Dynamics of Coral Reefs:
Part IV, The Sky Above
Chris Jury
Reefkeeping Magazine - December, 2006
http://reefkeeping.com/issues/2006-12/cj/index.php