Shouldn't we mimic nature also concerning alkalinity?

[JonasRoman]

Maybe a unnecessary clarification, but at least my main point here that calcification goes faster with higher dKH and pH is s not new; we quite well know how calcification works when the coral uses bicarbonate but has to expel hydrogen ions. That is a process that will be easier if the surrounding pH is higher. It also aids in the transport of hydrogenbicarbonate if the concentrationgradient is higher. I guess both mechanisms are responsible for the faster growth. It is interesting that corals do not seem to be able to fully control the speed of skeleton formation, but it is at least partial driven by concentration gradients and pH. In contrast to humans or other animals, that would be a catastrophe if you couldn't fully regulate the formation of the skeleton. Maybe that is a weakness of the coral, and that could be the reason we shouldn't push the limits too hard. But actually, what I are more interested in is the internal pH depending on the surrounding alkalinity and not the skeleton formation itself. So I'm talking about the cells from the soft tissue and how they struggle with keeping the internal pH with high surrounding bicarbonate concentration. I don't think much is written about that, but we at least know that fluctuations stress them. We will see if we can find some more data about this because it's advanced research and complicated to measure intracellular pH.

 

[schooncw]

I have a large amount of LPS in a 120 gallon and it consumes a lot of alk. I keep it around 9.2 w SeaChem Reefbuilder and is the only thing on a doser for my system.

 

[Randy Holmes-Farley Verified Community Expert]

Maybe a unnecessary clarification, but at least my main point here that calcification goes faster with higher dKH and pH is s not new; we quite well know how calcification works when the coral uses bicarbonate but has to expel hydrogen ions. That is a process that will be easier if the surrounding pH is higher. It also aids in the transport of hydrogenbicarbonate if the concentrationgradient is higher. I guess both mechanisms are responsible for the faster growth. It is interesting that corals do not seem to be able to fully control the speed of skeleton formation, but it is at least partial driven by concentration gradients and pH. In contrast to humans or other animals, that would be a catastrophe if you couldn't fully regulate the formation of the skeleton. Maybe that is a weakness of the coral, and that could be the reason we shouldn't push the limits too hard. But actually, what I are more interested in is the internal pH depending on the surrounding alkalinity and not the skeleton formation itself. So I'm talking about the cells from the soft tissue and how they struggle with keeping the internal pH with high surrounding bicarbonate concentration. I don't think much is written about that, but we at least know that fluctuations stress them. We will see if we can find some more data about this because it's advanced research and complicated to measure intracellular pH.

In the wild, growing fast is a huge plus to prevent being overrun by something else that grows faster. Same is true of land plants. The slow ones get shaded out by the fast ones.

So with that as a backdrop, many corals developed to grow fast. Given the fairly constant alk and pH in the ocean, perhaps they evolved to optimize their growth rate for that set of parameters, and never needed to slow down because high alk and pH is not something that naturally happens.

As an analogy, our desire for salt developed when it was hard to get. We mostly did not have to worry about getting too much. Now that it is easy to get, Our desire to obtain it can drive too much consumption that can lead to health problems.

 

[Ryan - Serious Reefs]

When we talk about parameters, we mostly agree that we should mimic nature, (maybe with one exception, the ratio of nitrogen/phosphorus could be a little higher, like 100 instead of 16).

But when it comes to alkalinity, there's a common sense that you should be a little higher than nature. We have, for instance, The Red Sea Company that proclaim a programme with super high, abnormal levels to increase growth.

I would say that it's best to be slightly above 7 and not too much higher. Thanks to my own devices, like Alkatronic, I have monitored and done thousands of KH measurements with just a few hours between, since 8 years back. This is not a scientific observation, just an observation, but in my systems, I am confident that I can see a healthier tank overall when I'm more close to 7.

Bicarbonate is crucial for determining the stability of the pH, but also the ability for the organism to keep its intracellular pH. Maybe the cell struggles with that if hco3 is too high? In human that is the case and hco3 is very regulated and should not be either too high or low.

Another observation in my tank, in the last year, I haven't had the slightest issue with dinoflagellates or cyano but constantly white sand.. That is also interesting; it's not impossible that it is connected to the 7.0 KH and also the stability around that.

I think it's impossible to prove this because everything is very multifactorial, but the pH is an extremely crucial parameter for the living cell and the hco3 is tightly connected to that, and my tank have never been this stable ever before. So its tempting to associate this with what I now do different.
Also, the coral grows fast enough, and colour is vivid. So KH 7.0 ish is for me with no doubt my new ref value for alkalinity.

Jonas

I’ve run many tanks between 7 and 12 dKH. As long as alkalinity is stable, I don’t think the exact number within that range is going to be the reason someone succeeds or fails but it can change the results.

I chose 9 dKH for a few reasons:

• It gives me a 2–3 dKH buffer from the danger zone.
• I don’t trust hobby-grade test kits enough to consistently nail 7 dKH with the accuracy I’d want.
• If a doser fails, a jug runs empty, or consumption changes I have roughly 2 dKH of room in either direction before I start getting seriously concerned.
• In my own tanks, I’ve consistently had better results at 9 dKH than at 7.

Similar to what you mentioned, I suspect pH plays a role here as well. Biologically, 7 dKH at a pH of 7.8 may be a very different environment than 7 dKH at a pH of 8.3

 

[CHSUB]

In the past my Alk was maintained at 9 or higher, as that was the recommendation. In the last few years my Alk has been closer to natural sea levels. Sometimes late in the day it gets below 7 because I dose at night only. I really couldn’t see a difference that I would attribute to Alk. There are to many variables that I believe could affect conclusions. Alk at around natural sea levels seems fine and appropriate. I doubt most hobby observation that draw any conclusions based on Alk including stability being important.

 

[Randy Holmes-Farley Verified Community Expert]

. I doubt most hobby observation that draw any conclusions based on Alk including stability being important.

I too tend to doubt the stability claim, at least if it cycles on a daily basis. That's different than steady alk for weeks then suddenly much higher or lower. Folks dosing once a day and having good success seem to prove this.

But the higher alk and pH leading to faster calcification (whether for good or bad) seems pretty strong and is easy to explain.

 

[CHSUB]

But the higher alk and pH leading to faster calcification (whether for good or bad) seems pretty strong and is easy to explain.

Yes I don’t disagree. That observation has been confirmed.

 

[Curiousbranching]

Isn't alkalinity partly dependent on the nutrient levels available for the corals? I prefer an Alk of 8.5-9 because it gives me more buffer time if my dosing equipment fails. A KH of 7 is just too risky.

 

[Randy Holmes-Farley Verified Community Expert]

Isn't alkalinity partly dependent on the nutrient levels available for the corals?

The only connection I am aware of between nutrients and alk is to not have nutrients too low if alk is high since that may lead to issues such as burnt tips in some SPS corals, perhaps due to the skeleton growing faster than tissue can keep up.

 

[Ryan - Serious Reefs]

The only connection I am aware of between nutrients and alk is to not have nutrients too low if alk is high since that may lead to issues such as burnt tips in some SPS corals, perhaps due to the skeleton growing faster than tissue can keep up.

I have always connected burnt tips to skeletal structure growing faster than tissue can keep up with. Potentially because essential aminos, nitrogen, or available protein is deficient in the tank.

But ... I just rewatched one of Dana Riddle’s videos where he suggested that burnt tips may be related to the combination of high PAR and high alkalinity.

• The tips of the coral receive the most light, so they have the highest potential rate of photosynthesis and reactive oxygen production.
• Higher carbonate alkalinity, in his example 12 dKH, increases the available inorganic carbon, which further increases the rate of photosynthesis and reactive oxygen production.
• Together, those factors may drive production of excess oxidants, leading to bleaching or tissue damage at the growth tips.

Sounded just as plausible as my current belief. However both could be true.

 

[Randy Holmes-Farley Verified Community Expert]

I seem to recall it was Dana who suggested the idea, at least first I saw, that tissue may not be keeping up with skeletal growth to explain burnt tips when nutrients are inadequate. Prior to that suggestion, I was unaware of a plausible hypothesis.

It is certainly true that there may be multiple contributing factors. It also seems confined to a small set of species, from what I have seen reported.

 

[JonasRoman]

In the wild, growing fast is a huge plus to prevent being overrun by something else that grows faster. Same is true of land plants. The slow ones get shaded out by the fast ones.

So with that as a backdrop, many corals developed to grow fast. Given the fairly constant alk and pH in the ocean, perhaps they evolved to optimize their growth rate for that set of parameters, and never needed to slow down because high alk and pH is not something that naturally happens.

As an analogy, our desire for salt developed when it was hard to get. We mostly did not have to worry about getting too much. Now that it is easy to get, Our desire to obtain it can drive too much consumption that can lead to health problems.

Agree with that, good point that coral in nature use growth rate as one of several competition mechanisms. What I mean is that we still define that as normal growth rate as its the natures rate. Supranormal growth rate is what I mean, that I refer to as maybe nonhealthy. I am following the analogue you mention:-)

Jonas