Stable pH vs Alk for Acropora

[arafas]

I seen great results chasing PH, growth, color, polyp extension. I also recently doing all day dose with versa for my alk and calc. which makes the PH rise steadily. my lowest 8.1 and highest 8.35. I also will run my range hood vent for now when I am at home until i get an ERV system. I did a 30 day CO2 test with a 300$ meter and you would be surprised how high CO2 goes with 2 people in the house. When I seen my ALK swing at some stage lets say .5 I never saw any issues as long as this was adjusted by the doser within same day lets say. Def since i have done higher PH i seen great results. I havent had any coraline in 2 years until I increased my PH.

 

[BradB]

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.

I don't mean to imply any negative connotations by saying your pH or Alk is unstable. From the numbers you post, I suspect your pH might be a bit lower than you think. You say your pH doesn't drop below 7.9 and is currently 8.34 - so I have no idea how high or low it goes, but clearly it is not ruler-flat all day.

 

[Epic Aquaculture]

I don't mean to imply any negative connotations by saying your pH or Alk is unstable. From the numbers you post, I suspect your pH might be a bit lower than you think. You say your pH doesn't drop below 7.9 and is currently 8.34 - so I have no idea how high or low it goes, but clearly it is not ruler-flat all day.

You can see the 24 hour range in the chart I posted. Low is 8.34 High is 8.48 avg is 8.38. I have also tested the Ph with a handheld Hanna Ph tester as well as my GHL profilux. My probes are also calibrated monthly so I think my numbers are quite accurate. The numbers between these devices are quite similar. I never stated that my Ph is the same throughout the day. I stated the range in my first post. But a swing of 1.04 Ph (8.34-8.48) is magnitudes of order smaller than a swing of say 3 (7.9-8.2 which many reefers state is their Ph range) so I would consider my Ph to be at the very least much more stable than most. The key is the low number. Once your Ph is below 8.3 at any time of the day, you are below NSW values. The lower the Ph the less your corals will take up CA and Alk. I have run my Ph as high as 8.6 with no detectable issues although my Alk did run over 10 when I did that.

 

[BradB]

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?”

I am saying that given a stable CO2 in the air near your tank, your Alk can only support a specific pH. And that this pH is going to be exactly the same for every other tank with the same Alk and CO2 in the air. Of course, this only applies if things that affect pH are held constant.

Coral growth is going to lower Alk and pH will only drop as a result of the Alk change. CO2 in the water also changes from photosynthesis. If you have enough growth and replace Alk fast enough to keep it stable, then what you replace it with will effect your pH. If you are adding kalkwasser, it will raise your pH much faster than Alkalinity and your pH will be higher. If you are adding Sodium Bicarbonate, your pH will drop, although the effect will be much less noticeable. If you dose kalkwasser or something that raises pH only with the lights on, your pH will swing wider and your alk will stay more stable. If you only dose with lights off, your pH will be flatter but your Alk will swing more.

 

[BradB]

pH below 8.3 is not below NSW values. There are a lot of other sources to quote, but all with similar ranges. Wikipedia gives 8.05 as the average Ocean surface pH (deeper water is lower pH).

Ocean acidification - Wikipedia

en.wikipedia.org

Above a pH of 8.4, Calcium Carbonate is going to precipitate rapidly and Alk drops fast. Either your tank defies physics, or you have a measurement error, likely a miscalibrated pH probe.

I've wasted too much time on this. I still am interested in other people growing Acropora successfully without a CO2 reactor, and if they dose at night, during the day, or on another schedule and why.

 

[Epic Aquaculture]

pH below 8.3 is not below NSW values. There are a lot of other sources to quote, but all with similar ranges. Wikipedia gives 8.05 as the average Ocean surface pH (deeper water is lower pH).

Ocean acidification - Wikipedia

en.wikipedia.org

Above a pH of 8.4, Calcium Carbonate is going to precipitate rapidly and Alk drops fast. Either your tank defies physics, or you have a measurement error, likely a miscalibrated pH probe.

I've wasted too much time on this. I still am interested in other people growing Acropora successfully without a CO2 reactor, and if they dose at night, during the day, or on another schedule and why.

We finally agree on something. This has been a waste of time. Wikipedia would not be something that I would refer to for accurate information, but to each his own. Here is an article from the EPA stating that pre-industrial revolution the ocean Ph averaged 8.2 https://www.epa.gov/ocean-acidification/understanding-science-ocean-and-coastal-acidification - here is the paragraph:

How Acidity is Measured: pH​

The acidity of a liquid is reported as pH. The lower the pH value, the higher the acidity of a liquid. Solutions with low pH are acidic and solutions with high pH are basic (also known as alkaline).
Prior to the Industrial Revolution, average ocean pH was about 8.2. Today, average ocean pH is about 8.1. This might not seem like much of a difference, but the relationship between pH and acidity is not direct. Each decrease of one pH unit is a ten-fold increase in acidity. This means that the acidity of the ocean today, on average, is about 25% greater than it was during preindustrial times.

At what point in history do you think the reefs were healthier, pre industrial times, or current times?

Here is an article from the South Pacific Regional Environment Programe That states that the current avg Ph on the South Pacific reefs is 8.1 with a variance of .3 https://www.sprep.org/attachments/Publications/CC/ocean-acidification.pdf

Believe what you want. Perhaps my instruments of measurement are completely wrong as well as those of all the other reefers and coral farmers who have had similar results and measurements as I have. Seems unlikely to me, but what do I know... Happy reefing!

 

[biecacka]

pH below 8.3 is not below NSW values. There are a lot of other sources to quote, but all with similar ranges. Wikipedia gives 8.05 as the average Ocean surface pH (deeper water is lower pH).

Ocean acidification - Wikipedia

en.wikipedia.org

Above a pH of 8.4, Calcium Carbonate is going to precipitate rapidly and Alk drops fast. Either your tank defies physics, or you have a measurement error, likely a miscalibrated pH probe.

I've wasted too much time on this. I still am interested in other people growing Acropora successfully without a CO2 reactor, and if they dose at night, during the day, or on another schedule and why.

I am growing them successfully in my tank. I use Kalk in my ATO. So it kicks on and off throughout the day as needed. I do not use a true slurry when compared to most slurry users. I also no that the ATO isn’t the most sound or effective way to dose the kalk. But, it works for me. 8.48 ph when I’m typing this. Alk 7.9 via Hanna checker. I know you specifically mentioned night, day, other schedule and I’m none of them so not sure if that has any value. Hahaha

corey

 

[Troylee]

I am growing them successfully in my tank. I use Kalk in my ATO. So it kicks on and off throughout the day as needed. I do not use a true slurry when compared to most slurry users. I also no that the ATO isn’t the most sound or effective way to dose the kalk. But, it works for me. 8.48 ph when I’m typing this. Alk 7.9 via Hanna checker. I know you specifically mentioned night, day, other schedule and I’m none of them so not sure if that has any value. Hahaha

corey

That’s how I roll.. I don’t dose anything but mag here or there.. I’m a huge fan of water changes thou.. years ago I never changed water for like 3 years while vodka dosing.. times have changed. Lol

 

[biecacka]

Yeah, I do a daily 1 gallon water change in the system via DOS. I do have a calcium reactor but it’s not online at the moment. The Kalk keeps up with my tanks demand for now. I don’t want to keep adding kalk to make it a true slurry though. At that point I don’t thing the ato would be the method, it would have to be its own separate reactor or something. So, when I get to that point I’ll put the CaRx online. Then the kalk can help with the lower ph from the CaRx.

corey

 

[arafas]

Is kalk more beneficial then 2 part, if we not talking in terms of Ph?

 

[Hats_]

I have grown acropora just fine in a relatively low pH tank (7.6 at night 7.9-8.1 during the day). after moving everything to my current tank and changing the lighting i lost a couple of colonies unfortunately but i am slowly getting back on track. the tank i bought came with a co2 scrubber and i am fiddling with it to tie it in since many people report success with it... I think stable alk is more important with the experience i have but i have a feeling that keeping values constant instead of widely swinging is easier for corals to adapt to in an aquarium environment. I dose 3 part during the day to keep alk (4x a day on different interval as Ca and Mg), mag (2 times a day) and calcium (4x a day) stable using a dosing pump

 

[Epic Aquaculture]

Is kalk more beneficial then 2 part, if we not talking in terms of Ph?

If we aren't taking Ph into account, then no - 2 part and Kalk are basically the same. If you are dosing a 2 part that contains Magnesium then the 2 part is actually the better product as Kalk does not have Magnesium. 2 part will help bolster Ph but not nearly to the extent that Kalk does.

 

[acrojunkie]

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?

I believe pH is somewhat important but tracking and maintaing a steady Alklinity is key with minimal adjustments.