What's the effect of alklalinity on SPS?

[Large Polyp Dave]

I know the alkalinity is a measure of the buffering capability of your aquarium.

I also know that you're supposed to keep it steady between 7 - 11


But what are the exact effects?

I've seen some spectacular SPS tanks with very low alk levels - sometimes even below 7.

And I've seen some equally beautiful SPS tanks with alk levels almost at 13.


Does anyone have any experiences they can comment on experiementing with different Alk levels in their tank?

 

[MiddletonMark]

Randy's section on Alk is good here:
http://reefkeeping.com/issues/2004-05/rhf/index.php

Well, Alk is measuring carbonate, which goes into the building of coral skeleton.

In my reading, the carbonate/bicarbonate that our corals desire for calcification is fairly low in `availability' in saltwater compared to something like Calcium. There's a paper out there that suggests higher Alk will increase calcification - but personally I prefer to be cautious and run only slightly above NSW [8-9 dKh].

I pay a lot of attention to Alkalinity, as IME I've had issues and mediocre growth when it gets below 7 [pH issues, too].
I've never run consistently over 10-11 dKh, so can't really comment on that, but while I didn't lose anything, much below NSW [6 dKh] didn't seem positive. [was accidental]

Just my 2 cents, I know I've got more to learn about this, too