Stable pH vs Alk for Acropora

[BradB]

Without dosing my pH is highest when my lights go off and lowest when they come on. Alk is going to swing the opposite of pH. I started dosing 2 part during the night only, this leveled pH very well, but it is going to increase my Alk swing. So I asked Randy in the Chemistry forum which was better, and he said there was convincing evidence either way. I did some more reading on this, and also have been thinking back on my own experience.

When I started more than 20 years ago, everyone chased pH. The only thing I added was kalkwasser (manually mixed and poured every day), and even Acropora grew well even under PC compacts and little flow. Kalkwasser has the drawback that even if you add 100% of your evaporation, you won't keep up with Calcium/Alkalinity in even a modestly successful tank. I did try a calcium reactor a few times, but decided against it. It is set-and-forget if everything goes well, but it is a lot more work than kalkwasser when something goes wrong. Corals didn't look nearly as good either. So I went back to kalkwasser and started adding 2 part, and both tested better and my corals looked better than anything else I've tried. But eliminating kalkwasser altogether saved a lot of my time, even though corals didn't do as well. Moving to an automatic doser saved even more time, but then I had no way to affect pH in the short term, and everyone at that point was saying not to chase pH. Replacing the doser with an Apex and DOS, I can now add 2 part at whatever time I want, so I have the option to chase pH again. I can even buy a Trident and dose to keep Alk perfectly stable and not worry about pH, and that seems like what the owners of the best Acropora tanks are doing. But meanwhile, my own tank seems to look better now that I leveled my pH even though my Alk is swinging more.

So I wanted to ask the Acropora community - do you primarily track and adjust pH or Alk? Have you changed? Which works better for you?

 

[blaxsun]

I am fairly new with acros, but I've grown a Chip's acro from half the size of my fist to the size of a small basketball in a less than a year. Alkalinity has ranged from 8.0-8.5dKH with pH fairly stable at 0.10-0.15ppm. I dose some other coral supplements as well but I honestly couldn't tell you what direct or indirect impact they have.

 

[Pistondog]

Alk is the key metric.

 

[gbroadbridge]

Without dosing my pH is highest when my lights go off and lowest when they come on. Alk is going to swing the opposite of pH. I started dosing 2 part during the night only, this leveled pH very well, but it is going to increase my Alk swing. So I asked Randy in the Chemistry forum which was better, and he said there was convincing evidence either way. I did some more reading on this, and also have been thinking back on my own experience.

When I started more than 20 years ago, everyone chased pH. The only thing I added was kalkwasser (manually mixed and poured every day), and even Acropora grew well even under PC compacts and little flow. Kalkwasser has the drawback that even if you add 100% of your evaporation, you won't keep up with Calcium/Alkalinity in even a modestly successful tank. I did try a calcium reactor a few times, but decided against it. It is set-and-forget if everything goes well, but it is a lot more work than kalkwasser when something goes wrong. Corals didn't look nearly as good either. So I went back to kalkwasser and started adding 2 part, and both tested better and my corals looked better than anything else I've tried. But eliminating kalkwasser altogether saved a lot of my time, even though corals didn't do as well. Moving to an automatic doser saved even more time, but then I had no way to affect pH in the short term, and everyone at that point was saying not to chase pH. Replacing the doser with an Apex and DOS, I can now add 2 part at whatever time I want, so I have the option to chase pH again. I can even buy a Trident and dose to keep Alk perfectly stable and not worry about pH, and that seems like what the owners of the best Acropora tanks are doing. But meanwhile, my own tank seems to look better now that I leveled my pH even though my Alk is swinging more.

So I wanted to ask the Acropora community - do you primarily track and adjust pH or Alk? Have you changed? Which works better for you?

Alk and Salinity are the most important parameters.

My SPS went nuts when I installed auto Alk measurement/dosing

I never really check pH but know it varies from 7.8 to 8.2 daily on average in my tank

 

[Epic Aquaculture]

I am fairly new with acros, but I've grown a Chip's acro from half the size of my fist to the size of a small basketball in a less than a year. Alkalinity has ranged from 8.0-8.5dKH with pH fairly stable at 0.10-0.15ppm. I dose some other coral supplements as well but I honestly couldn't tell you what direct or indirect impact they have.

I think you are confusing Ph with Phosphate. OP was asking about Ph.

 

[Epic Aquaculture]

Stabilizing Ph is the next level of SPS keeping. You can do well without stabilized Ph in the 8.3 range, but if you are able to keep it there (or better yet 8.4) you will see incredible benefits in growth, coloration, and overall health of your SPS. That being said it can be very difficult to achieve this in systems less than 300 gallons due to the amount of Kalk that you have to dose. On my display tank, which is 500 total gallons, I dose 10 gallons of Kalk per day.

 

[blaxsun]

I think you are confusing Ph with Phosphate. OP was asking about Ph.

Yeah, that's what I get for trying to reply as I'm rushing around... My bad. My pH ranges from 7.9 (low) to 8.2 (high) during the day. I don't use a Co2 scrubber.

 

[biecacka]

I think both are important. However, with the “newish“ kalk slurry trend, I think more people are sharing success with kalk only tanks. I don’t do a slurry as heavy as many do, but I do my version of a slurry in my ato and my sps growth has been steady. There a screenshot from my apex right now and that TSA fuzz picture is 10 months roughly.

corey

 

[billyocean]

I dose red sea alk via kamoer doser 12 times a day..so every 2 hours through night/day. My ph drops to around 8.1ish at night and shoots to 8.4/8.5 during the day. I'm not sure how or why but it works for me and grows acros well. I suppose if I added kalk during the night I could keep it higher through the night?

 

[BradB]

My SPS went nuts when I installed auto Alk measurement/dosing

Is going nuts good or bad?

 

[BradB]

Stabilizing Ph is the next level of SPS keeping. You can do well without stabilized Ph in the 8.3 range, but if you are able to keep it there (or better yet 8.4) you will see incredible benefits in growth, coloration, and overall health of your SPS. That being said it can be very difficult to achieve this in systems less than 300 gallons due to the amount of Kalk that you have to dose. On my display tank, which is 500 total gallons, I dose 10 gallons of Kalk per day.

Stable pH of 8.3 is impossible with stable Alk in an appropriate range and atmospheric CO2.

 

[BradB]

I think both are important. However, with the “newish“ kalk slurry trend, I think more people are sharing success with kalk only tanks. I don’t do a slurry as heavy as many do, but I do my version of a slurry in my ato and my sps growth has been steady. There a screenshot from my apex right now and that TSA fuzz picture is 10 months roughly.

corey

As I posted before, the best my tank ever looked was kalk only. This is a lot of manual effort and probably not sustainable without other supplementation.

 

[Troylee]

I don’t test my ph nor care what it is.. if I chased that number I would screw everything else up lol.. if you want to keep it elevated use a co2 scrubber on your skimmer but you need a valve to turn it on and off cause it will climb steadily some times.

 

[SPS2020]

Is going nuts good or bad?

Pretty sure that's a good thing.

 

[Epic Aquaculture]

Stable pH of 8.3 is impossible with stable Alk in an appropriate range and atmospheric CO2.

Never say impossible my friend. My 14 hour Alk range is 8.6-9.1 and my PH range is 8.36-8.43 Just because you haven't done it does not mean it can't be done... In addition, I (and many other coral farmers) have found that rock solid Alk #'s are not nearly as important at proper Ph (8.3-8.5). When I first began to "chase Ph" my Alk was very high and not stable, but as the carbonic acid left the tank my Alk came down into the range I was looking for and stabilized. It takes some time for this to happen. When the Ph was stable, but the Alk was not, there were no issues with the systems. At one point I accidentally raised Ph to 9.2 and Alk precipitated to 4.6 I was able to reduce Ph to 8.4 and raise Alk to 7.5 within 12 hours and you would have never known that the numbers were so crazy just by looking at the tanks. They never missed a beat (not that I would recommend this )

 

[BradB]

Never say impossible my friend. My 14 hour Alk range is 8.6-9.1 and my PH range is 8.36-8.43 Just because you haven't done it does not mean it can't be done... In addition, I (and many other coral farmers) have found that rock solid Alk #'s are not nearly as important at proper Ph (8.3-8.5). When I first began to "chase Ph" my Alk was very high and not stable, but as the carbonic acid left the tank my Alk came down into the range I was looking for and stabilized. It takes some time for this to happen. When the Ph was stable, but the Alk was not, there were no issues with the systems. At one point I accidentally raised Ph to 9.2 and Alk precipitated to 4.6 I was able to reduce Ph to 8.4 and raise Alk to 7.5 within 12 hours and you would have never known that the numbers were so crazy just by looking at the tanks. They never missed a beat (not that I would recommend this )

The laws of physics and chemistry say what can be done, this has nothing to do with what I have done personally. pH is fixed for a given CO2 and Alkalinity in otherwise natural sea water. If your tank photosynthesizes heavily, CO2 drops below atmospheric conditions. This is impossible to maintain as photosynthesis stops when the lights go out. Of course, you can maintain high pH all night with very high alk and get good growth, but this leads to tank crashes and burnt tips. Keeping alk normal and pH elevated means either somehow removing CO2 at night or using chemicals that shouldn't be in a reef.

 

[Epic Aquaculture]

The laws of physics and chemistry say what can be done, this has nothing to do with what I have done personally. pH is fixed for a given CO2 and Alkalinity in otherwise natural sea water. If your tank photosynthesizes heavily, CO2 drops below atmospheric conditions. This is impossible to maintain as photosynthesis stops when the lights go out. Of course, you can maintain high pH all night with very high alk and get good growth, but this leads to tank crashes and burnt tips. Keeping alk normal and pH elevated means either somehow removing CO2 at night or using chemicals that shouldn't be in a reef.

You're stating that it leads to burnt tips and tank crashes. That is not my experience nor the experience of many other coral farmers such as Chris Meckley at ACI. Yes the Kalk (Kalkwasser is certainly not a chemical that should not be in a reef and is the only method we use for Alk and Calcium supplementation - nothing else is used to keep Ph at 8.36-8.43) reactors that we run do maintain artificially higher Ph (Ph in those systems ranged from 7.9 - 8.2 prior to the reactors coming online), however Alk ranges from 8.6-9.1 which is a perfectly acceptable range. In fact at higher Ph a higher Alk can be kept which makes Calcium more bioavailable in the water leading to increased growth and better health in the corals. When I first started in the hobby in 1991 we ran Alk at 12. This was considered ideal for growth and coloration but we did not have the biomedia that exists today which can lower nutrients to unsafe levels and make higher Alk cause problems with the corals such as the burnt tips and tank crashes that you mentioned. Either way we can agree to disagree on this topic. but to answer your original question. It is my experience that stable Ph of 8.3+ is much more important than a stable Alk number. If I only monitored one parameter besides temp and salinity, it would be Ph.

 

[BradB]

I am stating that pH is the same for a given Alkalinity and CO2 in anything resembling seawater. Regardless of who owns the tank, or what they do. I am also pointing out this isn't universally for any solution - I can mix a very high pH and low Alkalinity solution with just RO water and Sodium Hydroxide and regardless of how long I expose it to atmospheric CO2 the pH will be higher than my tank and the alkalinity will be lower - but this relationship is universal for anything anyone grows coral in.

If your pH and Alk are stable and your pH is 8.3, your Alkalinity is around 12dKh. If your pH is 7.9 before your reactor kicks on and pH goes to 8.3, then your Alkalinity and pH are not stable. This doesn't mean your tank won't do well, and it backs my observation of running a kalkwasser-only tank that measures less than ideal but grows coral better than a tank with 2-part with either perfectly stable Alk or perfectly stable pH or anywhere in the middle.

 

[Epic Aquaculture]

I am stating that pH is the same for a given Alkalinity and CO2 in anything resembling seawater. Regardless of who owns the tank, or what they do. I am also pointing out this isn't universally for any solution - I can mix a very high pH and low Alkalinity solution with just RO water and Sodium Hydroxide and regardless of how long I expose it to atmospheric CO2 the pH will be higher than my tank and the alkalinity will be lower - but this relationship is universal for anything anyone grows coral in.

If your pH and Alk are stable and your pH is 8.3, your Alkalinity is around 12dKh. If your pH is 7.9 before your reactor kicks on and pH goes to 8.3, then your Alkalinity and pH are not stable. This doesn't mean your tank won't do well, and it backs my observation of running a kalkwasser-only tank that measures less than ideal but grows coral better than a tank with 2-part with either perfectly stable Alk or perfectly stable pH or anywhere in the middle.

I am not a chemist, so I'm only going to state my observations which are real world. My Ph does not drop to 7.9.

My Alk is not 12Dkh - Please note that the measurement pictured is PPM not DKH 155 PPM = 8.68 DKH.

So at this moment that I am typing, my Ph is 8.34 and my DKH is 8.68. You say this is not possible. I disagree. My Alkatronic is offline right now or I'd show you the 24 hour chart for Alk. The variance is 6 PPM for Alk which equates to a .34 variance. If those numbers aren't "stable" in your book, then I don't think I know of a tank that is "stable" Again I'm not saying the books are wrong (but they could be ) I'm simply showing you my real world measurements. You can draw your own conclusions...

For reference this is the display tank which is also tied to our SPS grow out system for a total water volume of around 700 gallons. It is a peninsula so there are about twice as many corals in the tank as you see from this side.

 

[biecacka]

My ph is 8.46 and my alk 7.9. It stays around there. @BradB, I have a question for you? I am just a hobbyist so this might not be the most scientific way to ask the question but I hope it comes across in way you can answer.
To me, it seems you are saying that an ph of “xxxx” can only support or will result in an Alk of “xxxx” correct? And the alk number is higher than what my tank reads. Here is my question, “since I have an elevated ph and experience slightly quicker growth in my tank, is it fair to assume that my alk could be lower because it gets consumed quicker?”


corey