Soft coral growth rate and pH

[Randy Holmes-Farley Verified Community Expert]

While most reefers accept that many hard corals grow faster at higher pH, the same may not be true of soft corals. What do you see in your reef tank with respect to soft coral growth vs pH (if anything)?

Hard corals have the challenging task of depositing calcium carbonate skeletons, and that is easier to do at higher pH. Exactly why on the molecular level may be a detail that eludes us, since there are at least two different explanations, but neither would be in play for soft corals.

Macroalgae, on the other hand, are more akin to many soft corals such as zoanthids in some ways. Macroalgae have several different ways to acquire CO2 for photosynthesis, and one of them (direct uptake of CO2) is strongly less active at higher pH. A second one too would be a little less active at higher pH (uptake of bicarbonate).

For example:

Photosynthesis and the Reef Aquarium, Part I: Carbon Sources by Randy Holmes-Farley - Reefkeeping.com

Relative rates of photosynthesis in seawater (measured by oxygen evolution) at pH 8.7 relative to pH 8.0. A value of 100 means that the rates were the same, and values below 100 indicate less photosynthesis at pH 8.7.

 

[Ziggy17]

I voted higher, but in reality, it could be a combination of higher and stable. My Zoas blasted off when I started keeping the PH between 8.2-8.3 (0.1 daily swing). But that was also right around the time that I was able to stabilize the Ph as prior I used to see swing of 0.4 daily with Alk swings. So perhaps the proper poll response would be “I don’t actually know”. I just don’t see a need to keep it stable and lower, as all is well, and I don’t want to poke the bear.

 

[Dragen Fiend]

Higher for me. Zoanthids in particular grew much faster and were a lot more bigger if I kept my PH above 8.2 compared to my typical 7.8

 

[A_Blind_Reefer]

Does faster growth even equate to better health?

 

[Randy Holmes-Farley Verified Community Expert]

Does faster growth even equate to better health?

I wouldn't assume so, but it might.

 

[Miami Reef]

Does faster growth even equate to better health?

Let me ask a counter question: does slower growth equate to better health?

Maybe growth isn’t correlated with health, but some of us want it.

 

[A_Blind_Reefer]

Let me ask a counter question: does slower growth equate to better health?

Maybe growth isn’t correlated with health, but some of us want it.

I think everyone wants better health….growth sure when everything is new or you’re in business selling coral. Once everything fills out, one might get tired of pruning, things getting unruly, and running out of room. I often wonder what happens when we run full turbo, redlining every parameter one can, and then decide to cut back when they get tired. I wonder the same thing with polyp extension on sps and tentacle extension on things like frogspawn or gonis. We like to see those polyps out and tentacles almost sticking out of the water, but does that equate to health. I’m waiting to see a “redfeild ratio” applied to ph/kh/n03 or the like. If one’s parameters as a whole fall in line of being within a certain range, and we peg a single parameter like ph, are we taking full advantage of that value. Meaning, if we raise ph, should we also be making other adjustments up/down/sideways to take full benefit? I sure as heck don’t know, ha.

 

[Miami Reef]

I added a zoa frag a few months ago, and it EXPLODED with growth. I never had luck with zoanthids growing when I was a beginner.

I keep a much higher pH than when I was a newb.

HOWEVER, I cannot and will not say that pH is the reason for the faster growth. It is nonsensical and illogical to assume that because there are countless other factors that have changed since I was a beginner.

 

[Pod_01]

My dilemma, when I used TM AFR and didn’t care about pH I could grow Zoa’s:

Now I am fiddling with pH and I am unable to keep any Zoa’s….

 

[Dan_P]

Let me ask a counter question: does slower growth equate to better health?

Maybe growth isn’t correlated with health, but some of us want it.

Growth rate might be a more useful measure of whether an organism exists in near optimal conditions AND is relatively free of disease. Of course, some idea of how fast organism typically grow would be needed to use this benchmark. An organism that is not growing, growing very slowly, or not maturing is abnormal and might be considered in poor health.

 

[JayM]

I voted "I don't notice", but "I have no idea" is better suited. I started about a year ago with 2 mushrooms, and they are approaching plague proportions as of a few months ago, yet the zoas I started with at the same time are doing well, but growth has not been nearly as explosive. Ph is always somewhere between 7.9-8.1 when I check it.

 

[ColorMeGone]

All my softies grow fast/healthy with 8 PH. But higher nitrates and some phosphates seem to be the ticket and what I look after the most.

 

[rishma]

My dilemma, when I used TM AFR and didn’t care about pH I could grow Zoa’s:

Now I am fiddling with pH and I am unable to keep any Zoa’s….

Nice pics!

Interesting observation. Do you think the only difference between happy growing zoas then and not being able to keep them now is a change in pH?

 

[Pod_01]

Nice pics!

Interesting observation. Do you think the only difference between happy growing zoas then and not being able to keep them now is a change in pH?

Unfortunately no, I am just not that disciplined.
I tend to always try different methods, additives, trace bottles, lighting etc… There are to just so many temptations and the claims…

Since my AFR experiment, I tried FM Balling light, FM BOLUS now I am using TM Original Balling with TM A and K (I do like this combination).
I experiment with hydroxide and kalk as well.

The Zoa issue may be pH related but it could be the other things like incorrect trace element mix etc…

 

[Miami Reef]

I tend to always try different methods, additives, trace bottles, lighting etc… There are to just so many temptations and the claims…

That’s so relatable.

 

[rishma]

Unfortunately no, I am just not that disciplined.
I tend to always try different methods, additives, trace bottles, lighting etc… There are to just so many temptations and the claims…

Since my AFR experiment, I tried FM Balling light, FM BOLUS now I am using TM Original Balling with TM A and K (I do like this combination).
I experiment with hydroxide and kalk as well.

The Zoa issue may be pH related but it could be the other things like incorrect trace element mix etc…

indeed, so relatable. I have finally accepted that experimenting, never leaving well enough alone, and messing up a good thing are just part of the hobby for me.

 

[Miami Reef]

indeed, so relatable. I have finally accepted that experimenting, never leaving well enough alone, and messing up a good thing are just part of the hobby for me.

It hasn’t bitten me in the butt yet. :P

 

[backbayreef]

It hasn’t bitten me in the butt yet. :p

Keyword here is “yet”? :)

 

[Pod_01]

Keyword here is “yet”? :)

It only takes 3-6 month to fix things once they go sideways…

 

[Miami Reef]

Keyword here is “yet”? :)

That’s just me being humble. I highly doubt I’ll kill my reef with my testing since I don’t go too astray. I do my research prior to adding anything.