Alkalinity stability? pH stability? Are they even different?

[BrandonS]

Very good write up and interesting question.

Not sure what it means but, part of my job is to record seawater parameters from a pipe line. So 60 feet down and 1000 feet out. Our PH swings everyday and also swings differently based on water temp, weather, etc.. I have never seen our ALK change. pH could be related to oxygen saturation however as that swings wildly with temperature.

 

[Brendank]

Randy,

Bulk Reef Supply has shown in testing that the pH matters. For the species of coral in their tests, higher pH at constant alkalinity correlated with higher growth rates. I believe pH was controlled by scrubbing CO2 from the water. They also tested growth rates at different alkalinity concentrations but it was not clear if pH was fixed in those tests. Higher alkalinity resulted in faster growth in those tests as well.

In much of the academic literature I’ve seen, it is asserted that the carbonate ion is used more readily in coral calcification. For the bicarbonate ion to be used, there is an energy penalty having to pump out the extra hydrogen ion. Furthermore, the lower the water pH, the more of an energy penalty pumping against the hydrogen ion gradient. It has also been established that the effect of pH on calcification rate is species specific. There is some species of porities that unlike most other species, has accelerated growth rates at lower pH.

 

[Garyjenson]

I never thought about the Kalkwasser idea, but it makes sense if it works and doesn't throw something else off. Will you have to do this forever, or will it eventually get back in check on it's own?

I use kalk in my top off. In theory it works like a manual calcium reactor. Now i adjust the ammount of kalk (calcium hydroxide, mrs wages pickling lime) depending on evap. I will be changing soon as the weather warms and i turn on the ac.
Everyone says that your tank will use these things in equal ammounts...i dont find this and i dont think its true for most. My tank ,180 gal , uses more alk. So if im not careful my calcium gets over 500. Currently im figuring out a way to peg to my calcium use and adjust alk with baking/washing soda...this would also potentially peg ph. It would require dosing baking soda at night and washing soda during the day...one thing randy didnt say was that coral dont grow at night so im not sure having bicarbonate more available would matter.

 

[Brendank]

An interesting side note on politicalization of science: Popular science articles on the effects of ocean acidification on coral reefs always neglect the contribution of the bicarbonate ion in coral calcification. If the reader is left to believe that lower oceanic pH causes a double-hit on calcification (one for smaller carbonate concentration and one for pH gradients), then CO2 emissions that cause ocean acidification is very bad. Of course we know that the cause and effect relationships are not so simple since bicarbonate ion must contribute to calcification and there is a species specific dependence on the roll of each parameter. There are also ongoing disputes between different authors in the field. Some publishing authors are also climate activists and other authors accuse journals of having differing publishing standards if the results support or not a particular political or activist agenda.

 

[maceto]

Fascinating info for a beginner like me. Thanks! @Randy Holmes-Farley

 

[Lasse]

An interesting side note on politicalization of science: Popular science articles on the effects of ocean acidification on coral reefs always neglect the contribution of the bicarbonate ion in coral calcification. If the reader is left to believe that lower oceanic pH causes a double-hit on calcification (one for smaller carbonate concentration and one for pH gradients), then CO2 emissions that cause ocean acidification is very bad. Of course we know that the cause and effect relationships are not so simple since bicarbonate ion must contribute to calcification and there is a species specific dependence on the roll of each parameter. There are also ongoing disputes between different authors in the field. Some publishing authors are also climate activists and other authors accuse journals of having differing publishing standards if the results support or not a particular political or activist agenda.

Can you support your thoughts with any links to published articles that not see the ongoing acidification as a threat to coral communities?

Sincerely Lasse

 

[lpsouth1978]

I know that I am guilty of mentioning to Randy just a couple of days ago, that I had no idea what my pH was because I wasn't going to "chase it" any way (kind of feel like my comment helped spur this thread). I have since calibrated and placed my pH monitor on the tank so at least I know what the value is. I think the biggest issue that I have, and I'm sure many others, with trying to stabilize pH is that, at least to my knowledge, there is no easy, cheap way to control it accurately and effectively in many cases.

The best option for me was to have my skimmer draw in fresh air from outside, but this only raised the pH. There were still swings from day to night. My current tank sits in the middle of the house and there is no way for me to draw in fresh air. I try to leave windows open, but it is getting VERY hot here (it will be 100 this weekend) so this is no longer an option.

I did switch to dosing soda ash, throughout the day and night, instead of baking soda in order to raise and keep pH higher, but what else can be done to make pH more consistent? Today my pH got up to 8.16 and is currently at 8.05 (its midnight now).

 

[Lasse]

@Randy Holmes-Farley Thank you for the link. Beside the proposed pathways for CO3 sources it was very interesting because it indicate a host induced light depended (with little or no interference from the zooxanthellae) ion transport (in order to enhance calcification rate) at the front of calcification. This pathway was more strongly induced in wavelengths around the 450 nm range compared with other wavelengths. This is maybe one of the reasons why royal blue and other 450 - 455 nm LEDs have been so very successfully in reefing. However - this is another question outside the topic for this thread - I´ll pass this issue further to the light forum and Dana Riddle

Sincerely Lasse

 

[Brendank]

Can you support your thoughts with any links to published articles that not see the ongoing acidification as a threat to coral communities?

Sincerely Lasse
[/

Lasse, the question is about the scale of effect, not denial of it. It will take some digging to find again but I have seen a reports and review article asserting bias in the academic journals by purposely holding to a different standard research that supports an argument that moderate ocean acidification doesn’t have a big effect on calcification. The review article essentially points to research showing some coral species are immune or may actually benefit from mild or moderate ocean acidification.

 

[Randy Holmes-Farley]

Randy,

Bulk Reef Supply has shown in testing that the pH matters. For the species of coral in their tests, higher pH at constant alkalinity correlated with higher growth rates. I believe pH was controlled by scrubbing CO2 from the water. They also tested growth rates at different alkalinity concentrations but it was not clear if pH was fixed in those tests. Higher alkalinity resulted in faster growth in those tests as well.

In much of the academic literature I’ve seen, it is asserted that the carbonate ion is used more readily in coral calcification. For the bicarbonate ion to be used, there is an energy penalty having to pump out the extra hydrogen ion. Furthermore, the lower the water pH, the more of an energy penalty pumping against the hydrogen ion gradient. It has also been established that the effect of pH on calcification rate is species specific. There is some species of porities that unlike most other species, has accelerated growth rates at lower pH.

Yes, higher pH does seem to lead to higher calcification rates in many corals, as does higher alkalinity.

I've not seen any recent literature claim that carbonate was actually taken up. How did they show it? It's a hard thing to distinguish between the uptake of two things that interconvert very rapidly. Can you post some?

One easy rationale for the higher calcification at higher pH (aside from the possibility of carbonate needed for uptake) is the ease of pumping out H+.

 

[Randy Holmes-Farley]

Randy,

Bulk Reef Supply has shown in testing that the pH matters. For the species of coral in their tests, higher pH at constant alkalinity correlated with higher growth rates. I believe pH was controlled by scrubbing CO2 from the water. They also tested growth rates at different alkalinity concentrations but it was not clear if pH was fixed in those tests. Higher alkalinity resulted in faster growth in those tests as well.

In much of the academic literature I’ve seen, it is asserted that the carbonate ion is used more readily in coral calcification. For the bicarbonate ion to be used, there is an energy penalty having to pump out the extra hydrogen ion. Furthermore, the lower the water pH, the more of an energy penalty pumping against the hydrogen ion gradient. It has also been established that the effect of pH on calcification rate is species specific. There is some species of porities that unlike most other species, has accelerated growth rates at lower pH.

Yes, higher pH does seem to lead to higher calcification rates in many corals, as does higher alkalinity.

I've not seen any recent literature claim that carbonate was actually taken up. How did they show it? It's a hard thing to distinguish between the uptake of two things that interconvert very rapidly. Can you post some?

One easy rationale for the higher calcification at higher pH (aside from the possibility of carbonate needed for uptake) is the ease of pumping out H+.

 

[Randy Holmes-Farley]

I use kalk in my top off. In theory it works like a manual calcium reactor. Now i adjust the ammount of kalk (calcium hydroxide, mrs wages pickling lime) depending on evap. I will be changing soon as the weather warms and i turn on the ac.
Everyone says that your tank will use these things in equal ammounts...i dont find this and i dont think its true for most. My tank ,180 gal , uses more alk. So if im not careful my calcium gets over 500. Currently im figuring out a way to peg to my calcium use and adjust alk with baking/washing soda...this would also potentially peg ph. It would require dosing baking soda at night and washing soda during the day...one thing randy didnt say was that coral dont grow at night so im not sure having bicarbonate more available would matter.

Well, your tank may very well use them in the expected proportion, it is just that limewater (kalkwasser) does not provide the right ratio. I used kalkwasser for 20 years, and I selected a low calcium/high alk mix (normal IO) for that very reason: it provides excessive calcium, as you observe.

The reason for this effect is that kalkwasser provides exactly the ratio of pure calcium carbonate, but in seawater or reef tanks, magnesium, and to a smaller extent, strontium, replace calcium in some of the deposited solids. Thus for a given alkalinity consumed, slightly less calcium is used that that unused calcium is why it rises over time when maintaining alkalinity exactly with kalkwasser.

 

[Randy Holmes-Farley]

Let us say that I construct a system that give a stable pH around 8.2 . Aeration with CO2 free air if pH drop below 8.2 and adding CO2 if pH rise over pH 8.2 Would it be optimal? I ask because in a test setup (short time 6 weeks) we saw a better growth in constant pH around 8.1 or 8.2 compared with sample with constant pH below 8.0 and over 8.2. I have always explained this with a thought that these result is due to "sweet spot" there the energy savings of of using CO2 instead of HCO3/CO3 for photosynthesis (and therefore more energy for calcification) and lower pH´s negative effect on calcification evens out. But maybe a stable content of HCO3 can be another explanation ?

Sincerely Lasse

Very interesting!

 

[Brendank]

Can you support your thoughts with any links to published articles that not see the ongoing acidification as a threat to coral communities?

Sincerely Lasse
[/

Lasse, the question is about the scale of effect, not denial of it. It will take some digging to find again but I have seen a reports and review article asserting bias in the academic journals by purposely holding to a different standard research that supports an argument that moderate ocean acidification doesn’t have a big effect on calcification. The review article essentially points to research showing some coral species are immune or may actually benefit from mild or moderate ocean acidification.

Can you support your thoughts with any links to published articles that not see the ongoing acidification as a threat to coral communities?

Sincerely Lasse

Lasse, this article should point you direction.

Can you support your thoughts with any links to published articles that not see the ongoing acidification as a threat to coral communities?

Sincerely Lasse

Can you support your thoughts with any links to published articles that not see the ongoing acidification as a threat to coral communities?

Sincerely Lasse

see: https://academic.oup.com/icesjms/article/73/3/529/2459146

 

[Afterburner]

I use kalk in my top off. In theory it works like a manual calcium reactor. Now i adjust the ammount of kalk (calcium hydroxide, mrs wages pickling lime) depending on evap. I will be changing soon as the weather warms and i turn on the ac.
Everyone says that your tank will use these things in equal ammounts...i dont find this and i dont think its true for most. My tank ,180 gal , uses more alk. So if im not careful my calcium gets over 500. Currently im figuring out a way to peg to my calcium use and adjust alk with baking/washing soda...this would also potentially peg ph. It would require dosing baking soda at night and washing soda during the day...one thing randy didnt say was that coral dont grow at night so im not sure having bicarbonate more available would matter.

When I tried Kalk a year ago, I found that I kept messing up my balance because my DIY ATO kept going off during water changes and other messing with the tank and my forgetting to turn it off, plus the evaporation changing issue due to temp swings. I was a mainly a FOWLR tank at that time so not really a big deal. When I moved to SPS and mixed reef, I had to get my toxic water in check and started actually testing water regularly. I quickly went to a two part dosing system for automation and picked ESV B-ionic which is working extremely well (especially for someone new to the game). The issue with supplementing with Kalk is that I am sure it would mess up the ionic balance for me and I am not as experienced as you or Randy are to dance the dance at the molecular level yet.
I did look at my CO2 scrubber last night and it is pretty much spent (pink).
In this pic, you guys are at the "What I think I do" stage, and I am probably closer to the "What my wife thinks I do" stage. We are all probably stuck at the "What I actually do" stage though.

 

[Lasse]

see: https://academic.oup.com/icesjms/article/73/3/529/2459146

To end this debate in this thread I refer to the authors own response to an article that have the same direction as your post.

Scientist Accuses The Times Newspaper of "Cherry Picking" on Ocean Acidification Story

A scientific journal editor has criticised the UK’s The Times newspaper for misinterpreting the findings of a special edition that looked at the science linking ocean acidification to impacts on marine organisms. The Times story claimed the publication, led by Dr Howard Browman, had concluded...

www.desmogblog.com

However - there is one very interesting article in this issue of ICES journal - maybe in line with the original post in this thread - the article - The Omega myth: what really drives lower calcification rates in an acidifying ocean. You can also find the article at page 558 in the complete ICES journal mentioned above. Go down to the PDF icon and the whole edition will be visible

Sincerely Lasse

 

[AlwaysHatingNathan]

This is something that I am very interested in as my apartment CO2 concentration hovers around 1200ppm and I have had issues with PH swings. I target my alk to 8.

I have issues with my apartment to, I could keep my kh stable but my ph was hard stuck at like 7.5. I had to add a CO2 scrubber to my protein skimmer. And it jumped right up to 8.2. I don’t like chasing my ph because I heard don’t but mine was hard stuck. And was because my apartment air is I’m guessing to stale and also from occasional burning something kitchen haha

 

[Brendank]

Lasse, this discussion is relevant to mention here to emphasize the species specific variability that coral have to the mix of water chemistry parameters and we must be careful consumers of information on the topic.

 

[Wtyson254]

I have issues with my apartment to, I could keep my kh stable but my ph was hard stuck at like 7.5. I had to add a CO2 scrubber to my protein skimmer. And it jumped right up to 8.2. I don’t like chasing my ph because I heard don’t but mine was hard stuck. And was because my apartment air is I’m guessing to stale and also from occasional burning something kitchen haha

This is my PH graph with my alk held solid around 8. I have a CO2 scrubber on my protein skimmer air intake with a recirculating design.

 

[Nhjmc]

I am new to hobby. Struggling to understand and get correct. So frustrating. In the last six months I’ve read probably 500 articles/posts/blogs joined several groups on Facebook and watched hundreds of youtube videos on reefkeeping. Probably gonna sound really dumb to most people that are advanced in this hobby but I’m struggling. Idk what I’m doing wrong. My alk tested 12-12.5 I tested twice with brand new salifert kit good till 2024 (Hanna alk check on order thank god) ca 550 mg 1290 but can’t get my ph over 8.0. I did a 5 gal water change hoping that helps. I have a RSM 130d.