Are CO2 levels important?

[arking_mark]

I've been looking into the pH/Alk/CO2 relationship and have been toying with "target" tank stability numbers based on CO2 levels.

We can look at some Hawaiian data to get a feel for natural levels. (https://www.pmel.noaa.gov/co2/file/Hawaii+Carbon+Dioxide+Time-Series)

So something like pH of 8.25 NBS and pCO2 levels around 350 (year 1994)...which would put the Alk around 6.8dKH.

However, that got me thinking that the real issue with CO2, may just be the pH levels and availability of Carbonate and Bicarbonate. As pH drops, calcification becomes harder.

So is it better to run a tank at:

Case 1: Natural CO2 levels
pH : 8.25
ALK: 6.8
pCO2: 350 (natural CO2 levels)

Or
Case 2: Elevated CO2 levels
pH: 8.25
Alk: 9
pCO2 : 470 (elevated CO2 levels)

Or does it even matter as needed Alk/Ca is readily available in both situations?

 

[blasterman]

My understanding of the calcification triangle is that virtually all captive tanks are at carbonate saturation levels already. pH levels would have to get real high and the tank super neglected to cause problems.

This is why I run into those wonder tanks with low alk levels and no dosing and yet SPS is thriving. Also explains calcium reactors and tanks that never see a pH above 7.9

The theory behind pH inhibiting calcification is pretty straightforward. Lots of extra protons wandering around the tank in the form of disolved CO2 makes a coral work harder to export protons (raise local pH) to precipitate carbonate and grow.

One thing that bugs me. Ive bought 3 pH meters over the past two years and while not expensive none of them works without constant calibration. They all drift higher in a short time. So....I get a little skeptical when I see a claim a sodium hydroxide scrubber is raising a tanks pH 3 points. I want to know how you keep CO2 saturated room air out of a tank simply because you are running air with a nominal lower percent of CO2 through your skimmer. Doesnt jive with me. Like running your AC during the summer with all windows and doors open and claiming its keeping your room cool.

 

[arking_mark]

My understanding of the calcification triangle is that virtually all captive tanks are at carbonate saturation levels already. pH levels would have to get real high and the tank super neglected to cause problems.

This is why I run into those wonder tanks with low alk levels and no dosing and yet SPS is thriving. Also explains calcium reactors and tanks that never see a pH above 7.9

The theory behind pH inhibiting calcification is pretty straightforward. Lots of extra protons wandering around the tank in the form of disolved CO2 makes a coral work harder to export protons (raise local pH) to precipitate carbonate and grow.

One thing that bugs me. Ive bought 3 pH meters over the past two years and while not expensive none of them works without constant calibration. They all drift higher in a short time. So....I get a little skeptical when I see a claim a sodium hydroxide scrubber is raising a tanks pH 3 points. I want to know how you keep CO2 saturated room air out of a tank simply because you are running air with a nominal lower percent of CO2 through your skimmer. Doesnt jive with me. Like running your AC during the summer with all windows and doors open and claiming its keeping your room cool.

A little off topic, but to answer your question about maintaining a higher pH:

Tuning a Skimmer / CO2 Scrubber for pH Control

On my reefing journey, I found Kalkwasse + Skimmer + CO2 Scrubber to be very effective for bringing my pH from 7.8 - 7.9 to 8.26 - 8.36. I guess most people would just leave it at that. However, I wanted to be more efficient with the CO2 scrubbing material so I wanted to implement a...

www.reef2reef.com

 

[mdb_talon]

So....I get a little skeptical when I see a claim a sodium hydroxide scrubber is raising a tanks pH 3 points. I want to know how you keep CO2 saturated room air out of a tank simply because you are running air with a nominal lower percent of CO2 through your skimmer.

I am one of those who see a .2 to .3 increase using either a co2 scrubber or outside air(which i switched to). I saw about .2 increase with scrubber and .3 with outside air.

The nice thing is just because you are skeptical of something you dont understand it....it thankfully still works.

As for a "nominal lower percent co2" that may be where your premise is wrong. In my area outside co2 levels average about 350. My house inside averages about double that and at times can approach 1000. That is far from a nominal difference. Of course this is also why it can make little to no difference for some people. If there is only a nominal difference in co2 levels there will be a minor to nonexistent impact to PH.

 

[Dkeller_nc]

Randy is probably the most appropriate person to comment on your question, as he's spent decades thinking about the consequences of inorganic chemistry in a reef environment, and written dozens of articles on the subject. My chemistry background is roughly the same as his from the standpoint of education, but I've spent my career dealing with proteins, cell culture, chromatography and other related life sciences subjects, not inorganic chemistry.

However, this is my understanding of your setup, and Randy can correct me if I get some or all of it incorrect.

The first observation is that it's not likely to be possible to maintain the pH of 8.25 in the two situations that you mention. In a carbonate-bicarbonate-carbonic acid-CO2 system, the pH of the solution is controlled by the partial pressure of CO2 in the atmosphere above the solution. That doesn't mean that you can't control the pH by altering the carbonate/bicarbonate ion ratio when making a carbonate buffer solution in a lab - that's a common procedure, and the chosen pH sets the ratio of sodium bicarb and sodium carbonate used to make the buffer. However, that pH is relatively temporary. Carbon dioxide from the air will eventually equilibrate with the buffer solution and alter the carb/bicarb ratio and thus the pH.

In a reef tank, you absolutely can maintain a non-steady state pH by the constant addition of acids/alkaline agents or the use of a CO2 scrubber to continuously (in effect) eject CO2 from the system. But that's a non-equilibrium situation - the pH of the tank water will return to the steady-state condition that is controlled by the CO2 concentration of the atmosphere around the tank as soon as these measures are discontinued.

From the standpoint of coral growth, however, the molar concentration of the carbonate ion in the carb/bicarb/carbonic acid equilibrium is the deciding factor, not necessarily the percentage of the bicarbonate vs. carbonate ion. The ratio of carb/bicarb ions in the tank water is controlled by the pH - as the pH goes down, the percent of the carbonate ion relative to the bicarbonate ion goes down. But that's not the same thing as the molar concentration of the carbonate ion in the solution. In the example of laboratory prepared buffers, you could have two solutions that are in equilibrium with two different CO2 concentrations (and thus have two different equilibrium pHs, and two different percentage compositions of carbonate/bicarbonate ions), but identical carbonate ion concentrations - Solution 1 could have a relative percent composition of 10% bicarbonate/90% carbonate, while Solution 2 could have a relative percent composition of 50% bicarbonate/50% carbonate, but both solutions would have an identical carbonate ion molar concentration. Obviously in this situation Solution 1 and Solution 2 will not have the same molar concentration overall, which is typically termed the alkalinity of the solution.

So potentially, one could frame your question as: can you practically overcome the need for constant manipulation of the pH in a reef tank by boosting the overall alkalinity and thus keep the carbonate ion molar concentration in the tank water the same (or boost it)?

In my opinion, I think there's a high probability of the answer being "yes", within certain limits. But answering this definitively requires knowledge of another factor that we don't really have available to us, which is what the maximum rate of skeleton formation in a coral is versus the carbonate ion concentration in the water. A further complicating effect is that corals have the ability to alter the carbonate/bicarbonate ratio in their tissues by biological processes, so even if the bicarbonate ion predominates in the tank water (because of lower pH), the animals may still be able to build calcium carbonate skeletons effectively.

Definitely an interesting question, and one I think reefkeepers (and marine biologists) will be debating for quite a number of years in the future.

 

[Ardeus]

CO2 levels of 1994 need an update:

It's shame no one was keeping SPS in the 1960's.

 

[Randy Holmes-Farley]

So is it better to run a tank at:

Case 1: Natural CO2 levels
pH : 8.25
ALK: 6.8
pCO2: 350 (natural CO2 levels)

Or
Case 2: Elevated CO2 levels
pH: 8.25
Alk: 9
pCO2 : 470 (elevated CO2 levels)

Or does it even matter as needed Alk/Ca is readily available in both situations?

Some hard corals will likely grow coral skeletons faster at higher alkalinity and the same pH. Assuming they have enough nutrients and you want faster growth, that seems a positive.

If you do not want faster growth, or do not want to maintain the nutrients needed for faster tissue growth to keep up with the skeleton growth, it may be a negative.

 

[arking_mark]

Randy is probably the most appropriate person to comment on your question, as he's spent decades thinking about the consequences of inorganic chemistry in a reef environment, and written dozens of articles on the subject. My chemistry background is roughly the same as his from the standpoint of education, but I've spent my career dealing with proteins, cell culture, chromatography and other related life sciences subjects, not inorganic chemistry.

However, this is my understanding of your setup, and Randy can correct me if I get some or all of it incorrect.

The first observation is that it's not likely to be possible to maintain the pH of 8.25 in the two situations that you mention. In a carbonate-bicarbonate-carbonic acid-CO2 system, the pH of the solution is controlled by the partial pressure of CO2 in the atmosphere above the solution. That doesn't mean that you can't control the pH by altering the carbonate/bicarbonate ion ratio when making a carbonate buffer solution in a lab - that's a common procedure, and the chosen pH sets the ratio of sodium bicarb and sodium carbonate used to make the buffer. However, that pH is relatively temporary. Carbon dioxide from the air will eventually equilibrate with the buffer solution and alter the carb/bicarb ratio and thus the pH.

In a reef tank, you absolutely can maintain a non-steady state pH by the constant addition of acids/alkaline agents or the use of a CO2 scrubber to continuously (in effect) eject CO2 from the system. But that's a non-equilibrium situation - the pH of the tank water will return to the steady-state condition that is controlled by the CO2 concentration of the atmosphere around the tank as soon as these measures are discontinued.

From the standpoint of coral growth, however, the molar concentration of the carbonate ion in the carb/bicarb/carbonic acid equilibrium is the deciding factor, not necessarily the percentage of the bicarbonate vs. carbonate ion. The ratio of carb/bicarb ions in the tank water is controlled by the pH - as the pH goes down, the percent of the carbonate ion relative to the bicarbonate ion goes down. But that's not the same thing as the molar concentration of the carbonate ion in the solution. In the example of laboratory prepared buffers, you could have two solutions that are in equilibrium with two different CO2 concentrations (and thus have two different equilibrium pHs, and two different percentage compositions of carbonate/bicarbonate ions), but identical carbonate ion concentrations - Solution 1 could have a relative percent composition of 10% bicarbonate/90% carbonate, while Solution 2 could have a relative percent composition of 50% bicarbonate/50% carbonate, but both solutions would have an identical carbonate ion molar concentration. Obviously in this situation Solution 1 and Solution 2 will not have the same molar concentration overall, which is typically termed the alkalinity of the solution.

So potentially, one could frame your question as: can you practically overcome the need for constant manipulation of the pH in a reef tank by boosting the overall alkalinity and thus keep the carbonate ion molar concentration in the tank water the same (or boost it)?

In my opinion, I think there's a high probability of the answer being "yes", within certain limits. But answering this definitively requires knowledge of another factor that we don't really have available to us, which is what the maximum rate of skeleton formation in a coral is versus the carbonate ion concentration in the water. A further complicating effect is that corals have the ability to alter the carbonate/bicarbonate ratio in their tissues by biological processes, so even if the bicarbonate ion predominates in the tank water (because of lower pH), the animals may still be able to build calcium carbonate skeletons effectively.

Definitely an interesting question, and one I think reefkeepers (and marine biologists) will be debating for quite a number of years in the future.

Please bare with me as I'm not a chemist.

I really appreciate your response!

Based on your response, my simplifiied understanding is as follows.

In any carbonate-bicarbonate-carbonic acid-CO2 system such as our tanks, the atmospheric CO2 partial pressure determines the pH and CO2 speciation.

So if I mixed up a batch of ASW, it's initial pH and Alk would be determined by the salts that made up the mix say 8.2 pH NBS and 7 dKH. If I then aerated that in an enclosed environment with no CO2, CO2 would eventually equalized with the saltwater and atmosphere resulting in the ASW losing Alk (escaping CO2) but increasing in pH.

Conversly, in a highly elevated CO2 environment, the CO2 would again find equilibrium with the ASW, but we would see a decrease in pH and rise in Alk.

Do I have this right?

 

[Randy Holmes-Farley]

Please bare with me as I'm not a chemist.

I really appreciate your response!

Based on your response, my simplifiied understanding is as follows.

In any carbonate-bicarbonate-carbonic acid-CO2 system such as our tanks, the atmospheric CO2 partial pressure determines the pH and CO2 speciation.

So if I mixed up a batch of ASW, it's initial pH and Alk would be determined by the salts that made up the mix say 8.2 pH NBS and 7 dKH. If I then aerated that in an enclosed environment with no CO2, CO2 would eventually equalized with the saltwater and atmosphere resulting in the ASW losing Alk (escaping CO2) but increasing in pH.

Conversly, in a highly elevated CO2 environment, the CO2 would again find equilibrium with the ASW, but we would see a decrease in pH and rise in Alk.

Do I have this right?

Addition or removal of CO2 cannot ever have any impact on alkalinity. It does impact what forms that alkalinity takes, from hydroxide at no CO2 to bicarbonate at high CO2.

 

[Randy Holmes-Farley]

Chemistry and the Aquarium: What is Alkalinity?

Randy provides an overview of alkalinity as to why it's important, how it's measured, and how can it be tested.

reefs.com

from it:

Alkalinity Facts​

There are several facts about total alkalinity that follow directly from the definition. Unfortunately, some of these have been misunderstood by some hobby authors.

One of these facts is termed The Principle of Conservation of Alkalinity by Pankow (“Aquatic Chemistry Concepts”, 1991). He shows mathematically that the total alkalinity of a sample CANNOT be changed by adding or subtracting CO2. Unfortunately, there is an article available on line, which claims otherwise, and encourages people to “lower alkalinity” by adding CO2 in the form of seltzer water. This is simply incorrect.

Forgetting the math for the moment, it is easy to see how this must be the case. If carbonic acid is added to any aqueous sample with a measurable alkalinity, what can happen?

Well, the carbonic acid can release protons by reversing equations 1 and 2:

(5) H2CO3 ==> H+ + HCO3–

(6) HCO3– ==> H+ + CO3—

These protons can go on to reduce alkalinity by combining with something that is in the sample that provides alkalinity (carbonate, bicarbonate, borate, phosphate, etc). However, for every proton that leaves the carbonic acid and reduces alkalinity, a new bicarbonate or carbonate ion is formed that adds to alkalinity, and the net change in total alkalinity is exactly zero. The pH will change, and the speciation of the things contributing to alkalinity will change, but not the total alkalinity.

This is not true for strong acids, however. If you add hydrochloric, sulfuric or phosphoric acids (or any acid with a pKa lower than the carbonic acid endpoint), there will be a reduction in the alkalinity.

 

[arking_mark]

Addition or removal of CO2 cannot ever have any impact on alkalinity. It does impact what forms that alkalinity takes, from hydroxide at no CO2 to bicarbonate at high CO2.

Aha! So I have it wrong!

 

[arking_mark]

Chemistry and the Aquarium: What is Alkalinity?

Randy provides an overview of alkalinity as to why it's important, how it's measured, and how can it be tested.

reefs.com

from it:

Alkalinity Facts​

There are several facts about total alkalinity that follow directly from the definition. Unfortunately, some of these have been misunderstood by some hobby authors.

One of these facts is termed The Principle of Conservation of Alkalinity by Pankow (“Aquatic Chemistry Concepts”, 1991). He shows mathematically that the total alkalinity of a sample CANNOT be changed by adding or subtracting CO2. Unfortunately, there is an article available on line, which claims otherwise, and encourages people to “lower alkalinity” by adding CO2 in the form of seltzer water. This is simply incorrect.

Forgetting the math for the moment, it is easy to see how this must be the case. If carbonic acid is added to any aqueous sample with a measurable alkalinity, what can happen?

Well, the carbonic acid can release protons by reversing equations 1 and 2:

(5) H2CO3 ==> H+ + HCO3–

(6) HCO3– ==> H+ + CO3—

These protons can go on to reduce alkalinity by combining with something that is in the sample that provides alkalinity (carbonate, bicarbonate, borate, phosphate, etc). However, for every proton that leaves the carbonic acid and reduces alkalinity, a new bicarbonate or carbonate ion is formed that adds to alkalinity, and the net change in total alkalinity is exactly zero. The pH will change, and the speciation of the things contributing to alkalinity will change, but not the total alkalinity.

This is not true for strong acids, however. If you add hydrochloric, sulfuric or phosphoric acids (or any acid with a pKa lower than the carbonic acid endpoint), there will be a reduction in the alkalinity.

So in essence, pCO2 only affects the speciation and pH?

 

[Randy Holmes-Farley]

So in essence, pCO2 only affects the speciation and pH?

Correct.

 

[arking_mark]

So I think I have a light bulb moment here!

With the understanding that pCO2 levels just influence the pH and carbonate speciation relationship I can better understand both cases.

For bath case 1 and case 2, the pCO2 will determine how pH and Alk behave with each other. If I raise Alk, pH will go up and visa-versa. If I increase the pCO2, Alk remains the same, but pH will drop. (By the way, for both case 1 and case 2, the pCO2 is the calculated relationship with the pH and Alk, meaning the system is stable.)

So which system is preferred? It would seem both cases provide adequate Alk and pH levels to maintain coral. However, case 2 (elevated pCO2) may be preferred due to the ability to maintain stable elevated Alk at a desired pH as some anecdotal evidence and some studies have shown increased coral growth. However, at this level, abiotic consumption is also increased and possibly a significant amount of CaCO3 may just be precipitated out. Also at higher Alk, in ULN systems, coral may experience issues with "burnt tips".

 

[Dkeller_nc]

Aha! So I have it wrong!

But you did have this correct: "In any carbonate-bicarbonate-carbonic acid-CO2 system such as our tanks, the atmospheric CO2 partial pressure determines the pH and CO2 speciation."

The alkalinity and carbon dioxide/carbonic acid/bicarb/carbonate equilibrium confuses at least some actual chemists on occasion, so don't feel bad.

 

[Dkeller_nc]

So I think I have a light bulb moment here!

With the understanding that pCO2 levels just influence the pH and carbonate speciation relationship I can better understand the both cases.

For bath case 1 and case 2, the pCO2 will determine how pH and Alk behave with each other. If I raise Alk, pH will go up and visa-versa. If I increase the pCO2, Alk remains the same, but pH will drop. (By the way, for both case 1 and case 2, the pCO2 is the calculated relationship with the pH and Alk, meaning the system is stable.)

So which system is preferred? It would seem both cases provide adequate Alk and pH levels to maintain coral. However, case 2 (elevated pCO2) may be preferred due to the ability to maintain stable elevated Alk at a desired pH as some anecdotal evidence and some studies have shown increased coral growth. However, at this level, abiotic consumption is also increased and possibly a significant amount of CaCO3 may just be precipitated out. Also at higher Alk, in ULN systems, coral may experience issues with "burnt tips".

This part is correct: "If I increase the pCO2, Alk remains the same, but pH will drop. (By the way, for both case 1 and case 2, the pCO2 is the calculated relationship with the pH and Alk, meaning the system is stable.)"

This part is not: "If I raise Alk, pH will go up and visa-versa."

In a carbonate-buffered aqueous system, including seawater, whether artificial or natural, the pH is solely controlled by the concentration of carbon dioxide in the atmosphere above the system. Note that's in equilibrium. As mentioned in my first post, there are a lot of things that aquarists can do to alter the pH of a reef tank that is temporary in nature. For example, if you violently bubble air (or any other gas) that has bee stripped of its CO2 through the water, that will have the effect of driving off some of the CO2 dissolved in the water and that is involved in the carbon dioxide/carbonic acid/bicarb/carbonate equilibrium. That will have the effect of increasing the pH of the water. When the bubbling of the gas without CO2 is stopped, the system will slowly re-equilibrate with the surrounding air, and the pH will go back down to its original value.

 

[arking_mark]

But you did have this correct: "In any carbonate-bicarbonate-carbonic acid-CO2 system such as our tanks, the atmospheric CO2 partial pressure determines the pH and CO2 speciation."

The alkalinity and carbon dioxide/carbonic acid/bicarb/carbonate equilibrium confuses at least some actual chemists on occasion, so don't feel bad.

Being wrong is great. It means I actually learned something. I'm just glad I kept digging. I was focused on dialing in my system and thought that natural CO2 levels might be a good target and couldn't fully understand why as it seemed that would mean going with lower than the 7dKH most recommend as a minimum. Now that I better understand this pH/Alk/CO2 relationship, I can see why that is probably not so important.

 

[Dkeller_nc]

Related to your question, there's been quite a bit of discussion on this board and on the 'net in general about accelerating coral growth at higher pHs (and how to achieve that pH in your tank). There's a reason why the higher pH might be effective at achieving higher coral growth. At a higher pH, the percentage of the total alkalinity that is in the form of the carbonate ion is higher, and therefore the total concentration of carbonate ion in the water is higher. As at least implied in the post I wrote above, coral use the carbonate ion to combine with the calcium ion in the water to build their skeleton. They are also capable of "converting" the bicarbonate ion to the carbonate ion in their tissues for adding to their skeleton. However, this conversion takes energy that the coral must expend, so it would make sense that if the coral has a higher concentration of carbon in the form of the carbonate ion available to it, and plenty of nutrients to support the growth of their soft tissue, than the overall growth of the coral might be accelerated.

I should note here, that the last two sentences in the above paragraph is the theory about why a higher pH in an aquarium might accelerate coral growth. I am not aware of a scientific paper that absolutely establishes that this is the case (though their might be).

 

[arking_mark]

This part is correct: "If I increase the pCO2, Alk remains the same, but pH will drop. (By the way, for both case 1 and case 2, the pCO2 is the calculated relationship with the pH and Alk, meaning the system is stable.)"

This part is not: "If I raise Alk, pH will go up and visa-versa."

In a carbonate-buffered aqueous system, including seawater, whether artificial or natural, the pH is solely controlled by the concentration of carbon dioxide in the atmosphere above the system. Note that's in equilibrium. As mentioned in my first post, there are a lot of things that aquarists can do to alter the pH of a reef tank that is temporary in nature. For example, if you violently bubble air (or any other gas) that has bee stripped of its CO2 through the water, that will have the effect of driving off some of the CO2 dissolved in the water and that is involved in the carbon dioxide/carbonic acid/bicarb/carbonate equilibrium. That will have the effect of increasing the pH of the water. When the bubbling of the gas without CO2 is stopped, the system will slowly re-equilibrate with the surrounding air, and the pH will go back down to its original value.

I get that. Maybe the term effective pCO2 should be used in these situations or aqueous CO? I'm probably using the wrong term.

You have an actual pCO2 and then CO2 consumers and producers.

In most tanks the pCO2 will vary day to day depending on who's home and how much outdoor air exchange you get.

Livestock in your tank will produce CO2 and photosynthetic organisms will consume CO2.

CO2 scrubberers will consume CO2.

At any given time your aqueous(?) CO2 will be something. If you stabilize your pH, your effectively stabilizing your aqueous(?) CO2. So it's as if your in equilibrium with a particular pCO2.

Does that sound right?

 

[arking_mark]

Related to your question, there's been quite a bit of discussion on this board and on the 'net in general about accelerating coral growth at higher pHs (and how to achieve that pH in your tank). There's a reason why the higher pH might be effective at achieving higher coral growth. At a higher pH, the percentage of the total alkalinity that is in the form of the carbonate ion is higher, and therefore the total concentration of carbonate ion in the water is higher. As at least implied in the post I wrote above, coral use the carbonate ion to combine with the calcium ion in the water to build their skeleton. They are also capable of "converting" the bicarbonate ion to the carbonate ion in their tissues for adding to their skeleton. However, this conversion takes energy that the coral must expend, so it would make sense that if the coral has a higher concentration of carbon in the form of the carbonate ion available to it, and plenty of nutrients to support the growth of their soft tissue, than the overall growth of the coral might be accelerated.

I should note here, that the last two sentences in the above paragraph is the theory about why a higher pH in an aquarium might accelerate coral growth. I am not aware of a scientific paper that absolutely establishes that this is the case (though their might be).

I bought into this and went down the pH rabbit hole, so to speak. My tanks natural home pH is around 7.9 at around a 7 dKH...so probably around pCO2 of 1000. This was during the winter so with change in season I'm guessing I'm now closer a pCO2 of 600.

Anyway, I went Kalkwasser pluse CO2 scrubber to stabilize my pH at a higher level and can now more tightly control it. I wasn't even seeing day/night swings till more recently (I suspect my 6 month old tank has more photosynthetic organisms and the house pCO2 has dropped due to seasonal changes)

Once I got stability/control of pH I started to try and stabilize my Alk and needed a target. I stumbled onto the pH/Alk/CO2 relationship and realized maybe certain #s make for a more stable system.

In retrospective, I could have probably dealt with my lower than desired pH with elevated Alk levels. However, that may have resulted in large pH swings as my house pCO2 changed from day to day and season to season.

Stability is king, so I'm happy with my results and just need to better stabilize Alk.