Is There A Optimal Alkalinity Level?

[monkeyCmonkeyDo]

I literally just watched this video before seeing this.thread.
Dont be like devin and raise ur alk to 12 after running carbon for 5+days. Ur coral will not like it. Lol.
D

 

[Cjeippert]

I just watched the brs video a couple months ago and upped alk to 9.0 from 8.0. Nitrate was undetectable, but everything but a hammer and acan were doing great. Most corals started looking bad so I turned my skimmer off for 4 days until I got nitrates to a steady 5. So now I only run skimmer at night to prevent nitrates from dropping too low. With my low nitrates and burnt sps, I am thinking about slowly going back to 8.3 dkh. Hard to keep everything happy in a mixed reef.

Interesting though, red sea recipes show like 10 & 11 for alk. I would have to dose nitrogen or remove my thriving refugium to do that. I like the refugium as it produces a crazy amount of amohipods, isopods, copepods to feed the many wrasse and dragonets.

 

[arking_mark]

So most reefers focus on target Alk and keeping that stable. However, there is a specific relationship between pH/Alk/CO2. Given any two of these numbers, you can calculate the third.

There is even a nice table for this: Marine Tank CO2SYS Table - Google Sheets

Now, this may be a fool's errand, but I went down the pH rabbit hole and am trying to stabilize my pH around 8.3.

At this pH, Alk should be at 7.7dKH to have natural seawater CO2 levels. How important that is, I'm not sure.

So my choice of optimal levels is pH = 8.3ish and Alk = 7.7dKHish.

If instead, I was focused on Alk and I wanted to keep it stable around 9dKH, and my indoor CO2 was say double that of natural seawater ~700ish my pH would settle in somewhere over 8.1.

My point is that stabilizing one number has implications on what other numbers will be.