CO2 Acidification / Skimmer Regulation

[Huey_Gnr]

BLUF: I am interested in anyone's experience with measurable data (Alk & pH) that shows what occurs in the tank levels over a 48 hour period from skimmer on 24/7 to skimmer off for the entire time block without dosing. Preferably an established tank with decent bio load.

And before I get roasted.... yes, I do realize I can conduct my own tests... but I use Hannah and am old so staying up to test every hour for 48 straight hours fueled by nothing more than curiosity and Monsters is a no-go; so I am more interested if someone with a probe has done similar tests that I can see their data.

I have read a lot on this forum with varying experiences and opinions, but have not been able to locate someone who has posted their data isolated solely to the skimmer.

As a side note, there are some VERY interesting articles on ocean acidification due to increases atmospheric CO2 levels and associated pH levels with measurable data demonstrating the climb of acidity in the ocean post-industrial age with forecasts out to 2100ish..... but I digress.

Genesis for my question: I want to begin the steady climb of nitrates in my tank (LPS/Softy) by dosing sodium nitrate, but realize that there are corresponding impacts to the ALK levels which I have worked hard over the past few months to dial in with dosing to keep the swing at +/- .2 daily. The addition of a CO2 scrubber has kept my pH levels in check right where I want them to be equally with only a media change every two weeks or so, but I run my skimmer 24/7 (for now). So I am trying to find the right balance of skimmer on/skimmer off timing in relation to dosing that gives me best times for adding NaHCO₃ and NaNO3 to still maintain my normalized balance of acidity/buffering capacity in the tank.

I also realize that like most living organisms, my tank would be resilient to these minor changes... but I am just as much fascinated with with the science of the hobby as I am the art of the hobby... so I want to conduct my research, plan what to do based on that research and then see how close I got to my calculations as they play out.

Thanks in advance!

 

[Dan_P]

BLUF: I am interested in anyone's experience with measurable data (Alk & pH) that shows what occurs in the tank levels over a 48 hour period from skimmer on 24/7 to skimmer off for the entire time block without dosing. Preferably an established tank with decent bio load.

And before I get roasted.... yes, I do realize I can conduct my own tests... but I use Hannah and am old so staying up to test every hour for 48 straight hours fueled by nothing more than curiosity and Monsters is a no-go; so I am more interested if someone with a probe has done similar tests that I can see their data.

I have read a lot on this forum with varying experiences and opinions, but have not been able to locate someone who has posted their data isolated solely to the skimmer.

As a side note, there are some VERY interesting articles on ocean acidification due to increases atmospheric CO2 levels and associated pH levels with measurable data demonstrating the climb of acidity in the ocean post-industrial age with forecasts out to 2100ish..... but I digress.

Genesis for my question: I want to begin the steady climb of nitrates in my tank (LPS/Softy) by dosing sodium nitrate, but realize that there are corresponding impacts to the ALK levels which I have worked hard over the past few months to dial in with dosing to keep the swing at +/- .2 daily. The addition of a CO2 scrubber has kept my pH levels in check right where I want them to be equally with only a media change every two weeks or so, but I run my skimmer 24/7 (for now). So I am trying to find the right balance of skimmer on/skimmer off timing in relation to dosing that gives me best times for adding NaHCO₃ and NaNO3 to still maintain my normalized balance of acidity/buffering capacity in the tank.

I also realize that like most living organisms, my tank would be resilient to these minor changes... but I am just as much fascinated with with the science of the hobby as I am the art of the hobby... so I want to conduct my research, plan what to do based on that research and then see how close I got to my calculations as they play out.

Thanks in advance!

Great question. What are your thoughts on a skimmer affecting alkalinity? I get the connection between possible improved CO2 exchange with a skimmer operating.

 

[Huey_Gnr]

Great question. What are your thoughts on a skimmer affecting alkalinity? I get the connection between possible improved CO2 exchange with a skimmer operating.

In my experience and research, the relationship between CO2 exchange and pH is the easy one. Reduce the CO2 levels in the tank, increase pH. (I am still researching Henry's Law and equilibrium... fascinating stuff.)

I increased the overall exchange rate with a skimmer, and then added a CO2 scrubber because I live in the south so my house doesn't get much fresh air from Apr-Oct... I just had to find the right amount of media to find the sweet spot on my pH levels. That took a little bit of time, but it is right where I want it now. 8.2 +/- .3 daily swing.

To your question: I wouldn't say that I feel the skimmer directly impacts the buffering capacity of my tank in and of itself. However, "when" I dose my sodium bicarbonate absolutely impacts the Alkalinity swing of my tank. And by dosing sodium nitrate, I am going to see a corresponding climb in my alkalinity. My assumption would be that by dosing sodium nitrate, the tanks demand for sodium bicarbonate will diminish as the increased nitrates will keep the Alkalinity up. (I will just need to find right daily amount to slowly increase without skyrocketing Alk). I have also read that many people turn their skimmers off for a period of time throughout a 24 hour day, specifically when adding phytoplankton for the organisms to consume and sodium nitrates for the nutrient levels. I believe that the skimmers are off while the lights are predominantly on due to the photosynthesis period.

But... with those changes in Alkalinity, I believe that I am going to be more susceptible to greater pH swings of the tank. Again, not that I am too terribly worried about that as long as I keep it reasonable, but if I can work out the timing of light schedule, skimmer on/skimmer off, nitrate dosing and still keep my acidity and buffering within my swing margins, I will consider that a success from my science part of the hobby standpoint.... if that makes sense?

If I am off in my thoughts, please let me know... I enjoy learning new things!

 

[Randy Holmes-Farley Verified Community Expert]

BLUF: I am interested in anyone's experience with measurable data (Alk & pH) that shows what occurs in the tank levels over a 48 hour period from skimmer on 24/7 to skimmer off for the entire time block without dosing. Preferably an established tank with decent bio load.

And before I get roasted.... yes, I do realize I can conduct my own tests... but I use Hannah and am old so staying up to test every hour for 48 straight hours fueled by nothing more than curiosity and Monsters is a no-go; so I am more interested if someone with a probe has done similar tests that I can see their data.

I have read a lot on this forum with varying experiences and opinions, but have not been able to locate someone who has posted their data isolated solely to the skimmer.

As a side note, there are some VERY interesting articles on ocean acidification due to increases atmospheric CO2 levels and associated pH levels with measurable data demonstrating the climb of acidity in the ocean post-industrial age with forecasts out to 2100ish..... but I digress.

Genesis for my question: I want to begin the steady climb of nitrates in my tank (LPS/Softy) by dosing sodium nitrate, but realize that there are corresponding impacts to the ALK levels which I have worked hard over the past few months to dial in with dosing to keep the swing at +/- .2 daily. The addition of a CO2 scrubber has kept my pH levels in check right where I want them to be equally with only a media change every two weeks or so, but I run my skimmer 24/7 (for now). So I am trying to find the right balance of skimmer on/skimmer off timing in relation to dosing that gives me best times for adding NaHCO₃ and NaNO3 to still maintain my normalized balance of acidity/buffering capacity in the tank.

I also realize that like most living organisms, my tank would be resilient to these minor changes... but I am just as much fascinated with with the science of the hobby as I am the art of the hobby... so I want to conduct my research, plan what to do based on that research and then see how close I got to my calculations as they play out.

Thanks in advance!

I’m not sure there is any general uncertainty on what a skimmer does for aeration and pH, though I do agree many reefers misunderstand it and or generalize their experience when that may not be appropriate.

There’s no such thing as isolating the effect to a skimmer in a reef tank as several processes impact pH, some of which the aquarist controls and some of which they cannot.

In my tank , where I used kalkwasser/limewater, turning off the skimmer raised the pH above where I wanted it, as expected.

 

[taricha]

BLUF: I am interested in anyone's experience with measurable data (Alk & pH) that shows what occurs in the tank levels over a 48 hour period from skimmer on 24/7 to skimmer off for the entire time block without dosing. Preferably an established tank with decent bio load.

Here's Eric Bornemann Need to Breathe part 3 article on O2 in reef tanks.
http://reefkeeping.com/issues/2005-08/eb/index.php

If you look at tank 1, it was an unskimmed 10gal clownfish tank with high bioload.
He doesn't address your questions about pH and alk at all. But the measurement of O2 illustrates the importance of gas exchange from skimmer. I wouldn't run a high bioload system without significant gas exchange during a dark period.

 

[Huey_Gnr]

Here's Eric Bornemann Need to Breathe part 3 article on O2 in reef tanks.
http://reefkeeping.com/issues/2005-08/eb/index.php

If you look at tank 1, it was an unskimmed 10gal clownfish tank with high bioload.
He doesn't address your questions about pH and alk at all. But the measurement of O2 illustrates the importance of gas exchange from skimmer. I wouldn't run a high bioload system without significant gas exchange during a dark period.

Awesome, thank you!