Relationship of Excess Nutrients/Coral Growth and Alkalinity

[victoly]

http://www.advancedaquarist.com/2015/5/aafeature

Some takeaways here:

" As corals and zooxanthellae use the same dissolved inorganic carbon (DIC) substrates (CO₂, HCO₃^{- (aka alkanity -ian)}) for calcification and photosynthesis, respectively [19], elevated nutrient-driven zooxanthellae densities may increase this competition in favour of the symbionts, thereby negatively affecting coral calcification."

"Our results have important implications for coral aquaculture and husbandry. If high alkalinity levels are maintained, coral growth rates can remain high under eutrophic conditions. This is especially relevant for home aquaria, which often experience higher than natural inorganic nutrient levels due to high fish stocking densities."

What they don't really touch on (and why would they, this is science) is coloration. I think anecdotally most of us have experienced the high nutrient = brownout phenomena, but what variables could we tweak to beat ourselves up less over nutrients if we can maintain good coloration at the potential expense of keeping alk high. Quick, someone with a huge tank full of SPS do some experimenting!

[FarmerTy]

My ears were ringing? Did someone call my name? Where am I and how did I get here?

[nvrEnuf]

I Admit right off the bat I only skimmed the article.

But pertaining to your question...I'll ask another...is this why red sea suggests so many additions to the "foundation" the higher in the Alk scale they go?

i.e. at DKH >12 they HEAVILY Recomend the addition of AT LEAST A&B reef energy, and suggest moniotring a good bit of the trace elems calling it "color pro" line or something like that.

Perhaps this is why I find it easier to just keep it at high 8's!!

[Reburn]

I would imagine that they "reccomend" dosing more additives the higher the DKH because the faster your corals will grow!!!! And to substain that growth they need amino acids among other additives because they are growing soooooo fast they need more food. So in turn, if you want to grow corals like us give us more of your money so you can grow corals like a pro.

MFrame. Where is the sarcasm button that we have asked for

Anecdotally I have experienced decreased growth and coloration with any all above 10. 8-9.5 was always my corals happy zone.

[FarmerTy]

Finally some evidence to back up why running your alk below 8.0 dKh is generally recommended when carbon dosing.

[Bpb]

I guess on paper it can make sense if you describe it correctly...but anecdotally, I've NEVER had anything good happen when my alk gets over 9 dKH. I am not a chemist. I do not have the foggiest idea why elevated alkalinity always causes problems for me but it does. My tank has always looked and behaved its best when alk is in the 6-8 dKH range. Furthermore. even if it fluctuates in that range I rarely notice anything out of the ordinary and everything looks happy, but simply nailing it down stable at 9+ and I have problems. Again, dont know why, just what I observe. I've only elevated mine slightly to 8.4 dKH right now, because that in turn has helped my PH averages come up which some SPS gurus on RC have indicated may help improve growth and possibly even reduce some stn problems (hey I was desperate).