Alkalinity stability? pH stability? Are they even different?

[Afterburner]

I have not checked pH in years. I just built a CO2 scrubber and never looked at it again. My tank is so mature that all I really check is Alk and sometimes PO4 every few days to weeks depending on how well my corals look.

 

[Randy Holmes-Farley Verified Community Expert]

I have not checked pH in years. I just built a CO2 scrubber and never looked at it again. My tank is so mature that all I really check is Alk and sometimes PO4 every few days to weeks depending on how well my corals look.

Many folks do not check or try to attain pH stability. That's part of the point of this thread. Not to check what people are doing, but what might be done and whether it would be beneficial. Adding a scrubber isn't very likely to increase pH stability, IMO, just to raise it.

That said, did you ever use the scrubber you built?

 

[Afterburner]

Many folks do not check or try to attain pH stability. That's part of the point of this thread. Not to check what people are doing, but what might be done and whether it would be beneficial. Adding a scrubber isn't very likely to increase pH stability, IMO, just to raise it.

That said, did you ever use the scrubber you built?

Randy,
Back when I checked pH every morning at the same time, it seemed to be low (if I remember correctly), so I built this scrubber (basically a tube full of Soda Lime) that I put at the air input to my scubber. My pH immediately went up and stayed good. In fact, when I went away on travel I managed to get the owner of my LFS to maintain my tank and he said my pH was the best he has ever seen. My pH meter eventually died or went out of calibration so it is now somewhere way back in my cabinet never to be seen again. Early in the COVID days, my tank got a lot more attention, but now I am all about less testing and a roller mat has set me free.
BTW: the soda lime turns pink when is absorbs the CO2, so use a clear tube so you can see when it is spent. Some say you need some way to reduce the humidity so the soda lime will last longer, but because I am in Florida with my AC on all the time to keep my tank from overheating, I did not add any dehumidification at the input. Here are a couple of pictures of it and the media. You will notice that the scrubber is a little more than half used. I refilled it over a month ago, and my skimmer runs 24/7. I always reseal the media bag after filling it. I think I bought the tube from BRS, and sourced the fitting to fit my skimmer air tube from Amazon. Make one, it is a cheap thing to try out, and I hope it works as well for others as it has for me. I am all about less things to test and worry about.

 

[Doreno]

I apologize if my post seems a little distant from the topic, but I believe that it is directly related to the question posed about the importance of a stable Ph.

And here's what I think, maybe in fact small changes in PH throughout the day are beneficial for corals rather than undesirable, and vice versa - a constant PH is more undesirable than varying within a day within 0.4.

Why do I think so?
Improvement of some natural processes is not always better.
For example light. In nature, corals grow in natural light for about 8 hours a day. We could improve this figure to 24 hours of constant lighting, i.e. to minimize the fluctuations of the PAR during the day, but will this "better" for our corals?
The same analogy can be drawn with PH, corals have evolved over millions of years, having adapted the most to the PH values that change during the day, and may be this is vital needs for SPS health... These are just my guesses and reflections.
What do you think about this?

 

[arking_mark]

I apologize if my post seems a little distant from the topic, but I believe that it is directly related to the question posed about the importance of a stable Ph.

And here's what I think, maybe in fact small changes in PH throughout the day are beneficial for corals rather than undesirable, and vice versa - a constant PH is more undesirable than varying within a day within 0.4.

Why do I think so?
Improvement of some natural processes is not always better.
For example light. In nature, corals grow in natural light for about 8 hours a day. We could improve this figure to 24 hours of constant lighting, i.e. to minimize the fluctuations of the PAR during the day, but will this "better" for our corals?
The same analogy can be drawn with PH, corals have evolved over millions of years, having adapted the most to the PH values that change during the day, and may be this is vital needs for SPS health... These are just my guesses and reflections.
What do you think about this?

Most reefers try to emulate the natural reef. So your PAR analogy isn't a good one. No one would stabilize PAR, in fact many try to have a realistic simulated day/night cycle that accounts for moonlight.

How much does pH fluctuate on a reef? If it's pretty much a constant then that is probably what one would want to provide. Maybe someone can chime in with natural reef pH fluctuations.

 

[Doreno]

Most reefers try to emulate the natural reef. So your PAR analogy isn't a good one. No one would stabilize PAR, in fact many try to have a realistic simulated day/night cycle that accounts for moonlight.

How much does pH fluctuate on a reef? If it's pretty much a constant then that is probably what one would want to provide. Maybe someone can chime in with natural reef pH fluctuations.

I googled a little about it and asked about it here https://www.reef2reef.com/threads/a...hey-even-different.711768/page-7#post-9375802
as I now know that the fluctuations in reef lagoons are probably at least 0.3-0.4 that are typical for home reef tanks.

More qualified reefers will correct me.​

 

[arking_mark]

I googled a little about it and asked about it here https://www.reef2reef.com/threads/a...hey-even-different.711768/page-7#post-9375802
as I now know that the fluctuations in reef lagoons are probably at least 0.3-0.4 that are typical for home reef tanks.

More qualified reefers will correct me.​

I found some interesting info...

Without the daily data, you can interpret this in several different ways as this is looking at and summarizing data for 30 days.

However, daily pH swings at reef locations are probably under 0.1 and in most cases well under this.

As most aquariums probably swing 2 to 4 times this amount, we are providing a less stable enviroment than our coral would experience in a natural reef.

Now what's best for our coral is still a question.

 

[Someshmuk]

What is the lowest alkalinity can be kept stable and maintain acropora health? Presuming its dkh<7 is the limit, wouldn't any dkh level kept 7+(daily alk consumption) be acceptable enough? if calcium and carbonate are used at the rate determined by the ph, (proof being from the ph test done by BRS showing up to 100% alkalinity consumption from 7.8 vs 8.3), why would the consistency of the density of carbonate, (total dkh), be more important or preferred then ph stability? From everything that i've been reading, ph swings are what stresses out coral, not the swings on the density of carbonate in the system.

 

[Plandauesq]

In order to increase pH, does it matter if you dose Kalk all day vs. when the lights are on or off?

 

[Randy Holmes-Farley Verified Community Expert]

In order to increase pH, does it matter if you dose Kalk all day vs. when the lights are on or off?

The answer is yes, but for follow up of normal pH questions, I'd suggest starting a different thread. This one is focused on a particular pH question: how stability of pH relates to alkalinity stability and what effect it may have on corals.

 

[Randy Holmes-Farley Verified Community Expert]

What is the lowest alkalinity can be kept stable and maintain acropora health? Presuming its dkh<7 is the limit, wouldn't any dkh level kept 7+(daily alk consumption) be acceptable enough? if calcium and carbonate are used at the rate determined by the ph, (proof being from the ph test done by BRS showing up to 100% alkalinity consumption from 7.8 vs 8.3), why would the consistency of the density of carbonate, (total dkh), be more important or preferred then ph stability? From everything that i've been reading, ph swings are what stresses out coral, not the swings on the density of carbonate in the system.

Alkalinity of 6.4 dKH is certainly perfectly fine for corals since that matches 35 ppt ocean water. I do not know what levels are the minimum, and it may depend on the pH. Higher alkalinity might be better, but not required.

The purpose of this thread is not to ask what is acceptable enough, but to get a deeper understanding of what is important and what is optimal.

The purpose is also not to ask if higher pH leads to faster hard coral growth. That's been known for a long time.

No experiment by anyone I have ever seen fully answers what effect pH stability has on hard coral growth rates, and how that relates to effects that many report from alkalinity stability (which is poorly documented, but widely claimed by folks who not have attained alk stability with automatic measurement and dosing of alkalinity).

Finally, I do not think there is any good evidence that pH swings stress corals, but if there were, how can you say whether that is a direct pH effect or a carbonate effect? Disentangling those effects is a very difficult experiment to carry out.

 

[ReefChasers]

We recently decided to stabilize our ph, where as before we were having swing around 8.1 night time low and 8.3/8.4 day time high. So after reading and some research (threads like this one, other people) we decided to stop dosing everything during the day and instead dose it all at night (mostly kalkwasser, around 10 gallons from end of photo period to start of the next one). We have 1200 gallon systems and they are pretty full of stony corals so we have a lot of consumption demand which allows the kalkwasser to do almost all the work.

We were able to balance the pH at 8.2 (basically 24/7) with the Alk holding steady around 8.5-9 (so stability across the board).

Of course I always want to push the limits (ahhhhhh!) so I wanted to get the steady ph up to 8.3/8.4 range (man wouldn't that be nice!) unfortunately the Alkalinity began to creep up (not the calcium at all, which is kinda strange). In fact, for the past 8 weeks we have been dosing 600ml of the 2 part bicarbonate supplement for calcium. What I don't understand is, if Kalkwasser is a balanced addition of Calcium/Alkalinity, why are we having to supplement an additional 600ml of calcium dosing just to keep CA above 400 (meanwhile alkalinity is rising?). I guess that's a good question to ask because it's quite confounding.

I've done a lot of research of course and some seem to suggest as steady pH rises the alkalinity that was 'bound up' (doesn't sound very scientific?) by excess co2 is released back to the water. I don't know if this is true, but right now I am thinking it is best to just hold the 8.2 ph steady with the DKH between 8.5-9 rather then try to push it up to 8.4 steady and have alkalinity rise dis-proportionately to calcium.

Overall we have noticed some anecdotally positive effects from stabilizing the pH this way, especially when it comes to Acropora. I'm now doing this at home with my personal reefs as well however it's a little more difficult because we do not have anywhere near the consumption level in our home personal tanks as we do in the Coral Farm tanks at work. It's basically impossible to dose enough Kalkwasser to stabilize the pH without having a ton of consumption requirements from stony corals.

I was trying to find ways to raise pH without disproportionately raising the alkalinity but after reviewing many of Randy's posts here on this forum (so very helpful) it has become clear to me that there is basically no good way to raise pH without raising alkalinity (Via chemical additions) so essentially having the coral consumption required to offset the alkalinity rise from chemical dosing is essential.

If anyone has any questions for me I'll be happy to answer them.

 

[arking_mark]

We recently decided to stabilize our ph, where as before we were having swing around 8.1 night time low and 8.3/8.4 day time high. So after reading and some research (threads like this one, other people) we decided to stop dosing everything during the day and instead dose it all at night (mostly kalkwasser, around 10 gallons from end of photo period to start of the next one). We have 1200 gallon systems and they are pretty full of stony corals so we have a lot of consumption demand which allows the kalkwasser to do almost all the work.

We were able to balance the pH at 8.2 (basically 24/7) with the Alk holding steady around 8.5-9 (so stability across the board).

Of course I always want to push the limits (ahhhhhh!) so I wanted to get the steady ph up to 8.3/8.4 range (man wouldn't that be nice!) unfortunately the Alkalinity began to creep up (not the calcium at all, which is kinda strange). In fact, for the past 8 weeks we have been dosing 600ml of the 2 part bicarbonate supplement for calcium. What I don't understand is, if Kalkwasser is a balanced addition of Calcium/Alkalinity, why are we having to supplement an additional 600ml of calcium dosing just to keep CA above 400 (meanwhile alkalinity is rising?). I guess that's a good question to ask because it's quite confounding.

I've done a lot of research of course and some seem to suggest as steady pH rises the alkalinity that was 'bound up' (doesn't sound very scientific?) by excess co2 is released back to the water. I don't know if this is true, but right now I am thinking it is best to just hold the 8.2 ph steady with the DKH between 8.5-9 rather then try to push it up to 8.4 steady and have alkalinity rise dis-proportionately to calcium.

Overall we have noticed some anecdotally positive effects from stabilizing the pH this way, especially when it comes to Acropora. I'm now doing this at home with my personal reefs as well however it's a little more difficult because we do not have anywhere near the consumption level in our home personal tanks as we do in the Coral Farm tanks at work. It's basically impossible to dose enough Kalkwasser to stabilize the pH without having a ton of consumption requirements from stony corals.

I was trying to find ways to raise pH without disproportionately raising the alkalinity but after reviewing many of Randy's posts here on this forum (so very helpful) it has become clear to me that there is basically no good way to raise pH without raising alkalinity so essentially having the consumption to offset it is essential.

If anyone has any questions for me I'll be happy to answer them.

You can definitely dial in and control pH through an oversized skimmer and recirculating CO2 scrubber.

Lessons learned in trying to maintain pH stability

For those interested in maintaining pH stability around +/- 0.05 I have a couple of lessons learned. These are things that I found out on my journey to pH stability. Prior to seeking pH stability my tank pH was consistently around ~7.9. However, much of this journey went on before the tank was...

www.reef2reef.com

 

[ReefChasers]

You can definitely dial in and control pH through an oversized skimmer and recirculating CO2 scrubber.

Lessons learned in trying to maintain pH stability

For those interested in maintaining pH stability around +/- 0.05 I have a couple of lessons learned. These are things that I found out on my journey to pH stability. Prior to seeking pH stability my tank pH was consistently around ~7.9. However, much of this journey went on before the tank was...

www.reef2reef.com

Oh yeah our skimmers are absolutely massive and we draw the air in from outside, that doesn't really stabilize your pH though that just makes your pH higher but the day time/night time swing still exists. Drawing air from the outside raises ph by 1/10th of a point essentially, this effects the minimum (night time ph) and maximum (day time ph) both but does nothing to 'stabilize' those two values.

So I consider the outside air/co2 scrubbing the air intake with media to be helpful for overall ph but useless in terms of stabilizing.

 

[Randy Holmes-Farley Verified Community Expert]

We recently decided to stabilize our ph, where as before we were having swing around 8.1 night time low and 8.3/8.4 day time high. So after reading and some research (threads like this one, other people) we decided to stop dosing everything during the day and instead dose it all at night (mostly kalkwasser, around 10 gallons from end of photo period to start of the next one). We have 1200 gallon systems and they are pretty full of stony corals so we have a lot of consumption demand which allows the kalkwasser to do almost all the work.

We were able to balance the pH at 8.2 (basically 24/7) with the Alk holding steady around 8.5-9 (so stability across the board).

Of course I always want to push the limits (ahhhhhh!) so I wanted to get the steady ph up to 8.3/8.4 range (man wouldn't that be nice!) unfortunately the Alkalinity began to creep up (not the calcium at all, which is kinda strange). In fact, for the past 8 weeks we have been dosing 600ml of the 2 part bicarbonate supplement for calcium. What I don't understand is, if Kalkwasser is a balanced addition of Calcium/Alkalinity, why are we having to supplement an additional 600ml of calcium dosing just to keep CA above 400 (meanwhile alkalinity is rising?). I guess that's a good question to ask because it's quite confounding.

I've done a lot of research of course and some seem to suggest as steady pH rises the alkalinity that was 'bound up' (doesn't sound very scientific?) by excess co2 is released back to the water. I don't know if this is true, but right now I am thinking it is best to just hold the 8.2 ph steady with the DKH between 8.5-9 rather then try to push it up to 8.4 steady and have alkalinity rise dis-proportionately to calcium.

Overall we have noticed some anecdotally positive effects from stabilizing the pH this way, especially when it comes to Acropora. I'm now doing this at home with my personal reefs as well however it's a little more difficult because we do not have anywhere near the consumption level in our home personal tanks as we do in the Coral Farm tanks at work. It's basically impossible to dose enough Kalkwasser to stabilize the pH without having a ton of consumption requirements from stony corals.

I was trying to find ways to raise pH without disproportionately raising the alkalinity but after reviewing many of Randy's posts here on this forum (so very helpful) it has become clear to me that there is basically no good way to raise pH without raising alkalinity (Via chemical additions) so essentially having the coral consumption required to offset the alkalinity rise from chemical dosing is essential.

If anyone has any questions for me I'll be happy to answer them.

A few comments…

1. Kalkwasser is not perfectly balanced. It adds excess calcium because real aquarium calcification uses magnesium and a little strontium in place of some of the calcium when calcium carbonate is formed.

2. The section you wrote about bound up alk being released at higher pH is not real or an explanation of any effects.

3. Underdosing of kalkwasser will show up first as lowering alk, despite the imbalance in 1. A drop of 1 dKH is easily detected by kit, but the corresponding calcium drop of about 7 ppm is often lost in the noise of testing.

4. Rising nitrate will result in an alk decline and will require additional alk dosing to stay steady, even then kalkwasser is maintaining calcium.

 

[ReefChasers]

A few comments…

1. Kalkwasser is not perfectly balanced. It adds excess calcium because real aquarium calcification uses magnesium and a little strontium in place of some of the calcium when calcium carbonate is formed.

2. The section you wrote about bound up alk being released at higher pH is not real or an explanation of any effects.

3. Underdosing of kalkwasser will show up first as lowering alk, despite the imbalance in 1. A drop of 1 dKH is easily detected by kit, but the corresponding calcium drop of about 7 ppm is often lost in the noise of testing.

4. Rising nitrate will result in an alk decline and will require additional alk dosing to stay steady, even then kalkwasser is maintaining calcium.

Thanks for the comments Randy. Yes I have read your postings extensively about Kalkwasser adding a little excess Calicum that can build over time but that would actually be the opposite effect of what we are seeing at the moment. The confounding part of what we are seeing is the opposite effect. Having to supplement 600ml of Calcium Chloride dosing in order to keep Calcium above 400 ppm even though alkalinity has risen almost 1.5 DKH over the past 8 weeks. I didn't think the 'bound up alkalinity' thing made a lot of sense -- but saw/heard a wholesale coral farm saying it on a podcast and thought maybe that is what is happening to us.

Definitely familiar with your postings re: Rising Nitrate affecting Alkalinity and thankful so much for all the info you put out there for us!

Again though we are still completely confounded by Alk rising up and Calcium going down when dosing 10 gallons of Kalkwasser per day over the past 8 weeks. We've had to add 600ml of Calcium Chloride dosing daily just to maintain the calcium but alk wont stop rising so it's pretty confusing.

I guess the Alkalinity rise could be related to nitrates being lowered then, we really have not seen that, our nitrates have been pretty steady but out of curiosity would you know how much ppm of nitrate would yield a certain change in Alkalinity? Say a drop of 2ppm nitrate would that be a big swing of alkalinity?

 

[arking_mark]

Oh yeah our skimmers are absolutely massive and we draw the air in from outside, that doesn't really stabilize your pH though that just makes your pH higher but the day time/night time swing still exists. Drawing air from the outside raises ph by 1/10th of a point essentially, this effects the minimum (night time ph) and maximum (day time ph) both but does nothing to 'stabilize' those two values.

So I consider the outside air/co2 scrubbing the air intake with media to be helpful for overall ph but useless in terms of stabilizing.

I strictly run my skimmer for pH control. Pulling in CO2 scrubbed air to raise pH and House air to lower pH.

 

[ReefChasers]

I strictly run my skimmer for pH control. Pulling in CO2 scrubbed air to raise pH and House air to lower pH.

That is an interesting method! But in our case we prefer not to lower the ph at all only to raise it. I don't think there is any scenario where we are actually wanting to suppress the pH because it is too high.

We let the ph get as high as it can during the day time and then attempt to maintain that ph Stability over the night time hours so that every day and night it is always the same (high). I could see your method being useful if we had the opposite scenario (we were wanting to lower it because it was rising uncontrollably or something to that effect).

Could also see it being helpful to 'stabilize' (not necessarily stabilize-high) the at-home pH levels of a smaller reef aquarium with less consumption (not possible to dose enough additives to keep it stable-high).

I guess I should have clarified though that we want to stabilize it at a high level, rather then just stabilize it period.

 

[Randy Holmes-Farley Verified Community Expert]

Thanks for the comments Randy. Yes I have read your postings extensively about Kalkwasser adding a little excess Calicum that can build over time but that would actually be the opposite effect of what we are seeing at the moment. The confounding part of what we are seeing is the opposite effect. Having to supplement 600ml of Calcium Chloride dosing in order to keep Calcium above 400 ppm even though alkalinity has risen almost 1.5 DKH over the past 8 weeks. I didn't think the 'bound up alkalinity' thing made a lot of sense -- but saw/heard a wholesale coral farm saying it on a podcast and thought maybe that is what is happening to us.

Definitely familiar with your postings re: Rising Nitrate affecting Alkalinity and thankful so much for all the info you put out there for us!

Again though we are still completely confounded by Alk rising up and Calcium going down when dosing 10 gallons of Kalkwasser per day over the past 8 weeks. We've had to add 600ml of Calcium Chloride dosing daily just to maintain the calcium but alk wont stop rising so it's pretty confusing.

I guess the Alkalinity rise could be related to nitrates being lowered then, we really have not seen that, our nitrates have been pretty steady but out of curiosity would you know how much ppm of nitrate would yield a certain change in Alkalinity? Say a drop of 2ppm nitrate would that be a big swing of alkalinity?

In terms of alk and nitrate, it takes a 50 ppm drop in nitrate to add 2.3 dKH.

This has more on the alk calcium demand issue in general:

When Do Calcium and Alkalinity Demand Not Exactly Balance? by Randy Holmes-Farley - Reefkeeping.com

 

[ReefChasers]

In terms of alk and nitrate, it takes a 50 ppm drop in nitrate to add 2.3 dKH.

This has more on the alk calcium demand issue in general:

When Do Calcium and Alkalinity Demand Not Exactly Balance? by Randy Holmes-Farley - Reefkeeping.com

Okay so basically it's impossible the results of what we are seeing with alk up and calc down could be related to nitrate because at most it has only moved around 2ppm total over these 8 weeks.


Reef Ghosts likely to blame, we all got em!