Is pH fluctuation a good thing?

[Earl Karl]

So we know that pH rises during the day and falls during the night as CO2 tends to increase during this period. In the ocean's reef, there is usually a 0.2-0.5 units fluctuation.

However, I run a refugium strictly for nutrient export (no pods or anything), so I use a pretty strong grow light that gives me about 400-500 par on the chaeto. I run it reverse cycle to alleviate pH swings.

But are pH swings really a bad thing?

There's a level of pH (I believe 8.1 or lower) where aragonite will begin dissolve as a alk. buffer and trace mineral addition. Isn't that a good thing? However I do not know if this is true, this is something I was told.

With this in mind, should I still be running reverse cycle, or should I just run it at the same time the display is on? I feel like having it the refugium light on at the same time as the display will create competition for nutrient export between the microalgae that I have on the display sandbed occasionally (I do tend to have high phosphates) and the chaeto in the refugium, but the light in the chaeto is much stronger and better spectrum than the display light so the refugium will pretty much outcompete the algae in the display.

The reverse cycle seems to be a 24 hours nutrient export. During the day, the microalgae in the display seems to be working, while during the night, the chaeto is working. No competition really, more like synergy if anything. Just that I have algae in the display. My phosphates are 0.4, pretty high as expected with high stock and multiple feedings, but my acros seems to have the best colors at that level, but grow pretty slow compared to lower levels. Any higher though, they turn brown.

However, in the end, I do not want algae in my display. I wonder if running the lights at the same time will let the refugium outcompete the algae in the display, rather than working together.

I will switch schedule if the benefits of dissolved aragonite is true. If not, I will stick with the reverse cycle. Hopefully @Randy Holmes-Farley can help me with this.

 

[Cory]

I think that anything that mimicks the ocean is the best way to go including ph.

 

[Earl Karl]

Ok, that's a very good point. I'll take that into consideration, but I need more info on this to make sure I'm doing the best for my reef tank.

 

[Earl Karl]

Can anyone else chime in on this?

 

[Ron Reefman]

pH fluctuations are perfectly normal. Mine used to go from 7.8 to 8.0 every day. Don't sweat pH unless it gets WAY out of line and the odds of that happening are so small that many reefers never even check pH anymore. I sure don't. I haven't checked a pH level in any of my tanks for 4 or 5 years now... and I sold all but one pH test kit (I had a couple of pH meters).

The driving force behind pH levels is CO2 in the water which is primarily due to the CO2 levels in the air inside your home. Close up the house for A/C summers or furnace winters and your CO2 levels will rise and your pH levels will drop. Some reefers even import outside air through their skimmer to lower the CO2 levels and increase pH.

I'm not sure at what pH level aragonite will start to 'breakdown'. That is what a calcium reactor does and I believe the pH level has to be quite a bit lower than 7.8. But I've never used one and I'm not 100% sure at what pH level they run.

In short, don't chase your pH level. It is what it is and odds are, unless you have something seriously wrong in your tank, it's OK.

 

[Stickboy15]

I believe it’s 7.6 when skeletons start to dissolve

 

[Super Fly]

as per Melev's Reef, "dont chase the PH". He explains it here...
http://www.melevsreef.com/articles/dont-chase-the-ph

 

[pickupman66]

I am a pretty firm believer of not bothering with PH unless you are seeing swings from 7.8 to 8.0 in a matter of 30 minutes or so. My tank has run very well at 7.8. it has run well at 8.0. I hardly ever even look at the Controller's PH reading. So much so that in my new Reef-pi build, I do not plan to add PH. I run my Fuge 24x7.

Here is about 15 days worth.

 

[Earl Karl]

@pickupman66 What are your phosphates while running the fuge 24/7? Do you get good nutrient reduction?

Another question, does running the fuge at the same time as the display help the fuge compete against the algae in the display?

 

[ShadowR55]

I don’t understand why this “don’t chase PH” keeps being regurgitated? There’s proof that corals grow faster at a higher PH, I had to more than double my alk and calcium dosing after increasing my PH from around 7.95 to 8.2 using a CO2 scrubber.

 

[Scrubber_steve]

pH certainly swings on a natural reefs but tanks ain't the ocean, & stuff happens in tanks that doesn't happen in the ocean. Maintaining stable pH in an aquarium is just one less possible stress on corals if other things ain't quite right. In an aquarium oxygen levels drop after lights out also & illuminating algae is the best method to remove excess co2 & convert it to O2.
I run my scrubber at night & leave it off during the day so the corals can take advantage of the trace inorganic nutrients made available

 

[Ron Reefman]

I don’t understand why this “don’t chase PH” keeps being regurgitated? There’s proof that corals grow faster at a higher PH, I had to more than double my alk and calcium dosing after increasing my PH from around 7.95 to 8.2 using a CO2 scrubber.

I'm not saying you are wrong, I'm just saying that in over 15 years in the hobby I've never heard anybody talk about corals growing 'faster' at higher pH. And just how high should the pH be?

I'd love to see a couple of links to so science, especially from a professional like Randy Holmes Farley.

Thanks.

 

[pickupman66]

@pickupman66 What are your phosphates while running the fuge 24/7? Do you get good nutrient reduction?

Another question, does running the fuge at the same time as the display help the fuge compete against the algae in the display?

I feed pretty heavily. Right now last time I checked my phosphates were 0.08 with my Hannah checker. I started it on this type of a schedule because I had high nutrients.

 

[ShadowR55]

I'm not saying you are wrong, I'm just saying that in over 15 years in the hobby I've never heard anybody talk about corals growing 'faster' at higher pH. And just how high should the pH be?

I'd love to see a couple of links to so science, especially from a professional like Randy Holmes Farley.

Thanks.

https://scholar.google.com/scholar?hl=en&as_sdt=0,10&q=increased+coral+growth+rate+PH&btnG=#d=gs_qabs&p=&u=#p=h1rMbZSRTnQJ

 

[Danh Ngo]

Your PH swing is fine, not too much. 0.4 Phosphate is high, I have a heavy stocked tank, using cheato as a main nutrient export, no3 < 4, po4 <0.04 for me all the time, I feed twice a day. My chaeto triple the size in the month, algea in DT could be your fuge is not working effeciently

 

[Scrubber_steve]

https://scholar.google.com/scholar?hl=en&as_sdt=0,10&q=increased+coral+growth+rate+PH&btnG=#d=gs_qabs&p=&u=#p=h1rMbZSRTnQJ

I'm not saying you are wrong, I'm just saying that in over 15 years in the hobby I've never heard anybody talk about corals growing 'faster' at higher pH. And just how high should the pH be?

I'd love to see a couple of links to so science, especially from a professional like Randy Holmes Farley.

Thanks.

I watched one of the BRSTV utubes with WWCs yesterday & the WWCs fellow made the claim that they get greater growth with higher pH.

The claim was anecdotal of course.

 

[vegamedic]

I'm just saying that in over 15 years in the hobby I've never heard anybody talk about corals growing 'faster' at higher pH

it's been shown in literature for close to 20 years, and remains an active area of research due to concerns about ocean acidification. here's the first 5 links i got searching for "coral calcification at higher ph"

https://www.sciencedirect.com/science/article/abs/pii/S0009254118304443
http://bio.biologists.org/content/3/6/489
https://www.soest.hawaii.edu/oceanography/GES/Thesis/MiaDelano.pdf
https://www.esrl.noaa.gov/gmd/icdc7/proceedings/abstracts/mcneil1HI75.pdf

https://coastal.er.usgs.gov/crest/research-themes/community-metabolism.html <-- this page has a pretty thorough list of papers you can work through, but here's a nice takeaway:

"A number of experimental and modeling studies (e.g. Kleypas et al., 1999; Marubini and Atkinson, 1999; Langdon et al., 2000; among many others) indicate that ocean acidification [i.e. lower pH] will result in a decrease in rates of calcification by reef organisms"

 

[Scrubber_steve]

it's been shown in literature for close to 20 years, and remains an active area of research due to concerns about ocean acidification. here's the first 5 links i got searching for "coral calcification at higher ph"

https://www.sciencedirect.com/science/article/abs/pii/S0009254118304443
http://bio.biologists.org/content/3/6/489
https://www.soest.hawaii.edu/oceanography/GES/Thesis/MiaDelano.pdf
https://www.esrl.noaa.gov/gmd/icdc7/proceedings/abstracts/mcneil1HI75.pdf

https://coastal.er.usgs.gov/crest/research-themes/community-metabolism.html <-- this page has a pretty thorough list of papers you can work through, but here's a nice takeaway:

"A number of experimental and modeling studies (e.g. Kleypas et al., 1999; Marubini and Atkinson, 1999; Langdon et al., 2000; among many others) indicate that ocean acidification [i.e. lower pH] will result in a decrease in rates of calcification by reef organisms"

Just 'one' of the problems with those studies, is, they don't explain how calcifying organisms were building reefs when atmospheric CO2 levels were over 5,000ppm, some 12.5 times higher than now.
Was the pH of the water on those reefs little different to now? Or quite different, but organisms coped despite?

 

[Scrubber_steve]

This paper you linked http://bio.biologists.org/content/3/6/489
Our preliminary results suggest that within the current oxygen and pH range, oxygen has substantial control over coral growth, whereas the role of pH is limited.

Interesting

This paper interesting in relation to longer term pH rather than daily fluctions
Coral tricks for adapting to ocean acidification

 

[Earl Karl]

Thanks for the help, I really appreciate it. You guys are really wonderful.

My fuge wasn't working the way I wanted it to because the feeding was just too much for the fuge can handle. I feed my tank, which has Purple Queen Anthias, five times a day. My No3 is less than 5ppm however.

I plan to run it 24/7. Macroalgae don't need a dark cycle like terrestrial plants and I'm not growing pods as I directly feed my dragonets 3 times a day (Good thing I work at home). I feel like this would also keep my pH high, yet still get that natural fluctuation, and get the best use of nutrient reduction.