Was in the 8-8.5 range but jumped up to 10.5 over the course of the last week while playing with Randy's recipe #1. I plan on letting it come back down to the range I was targeting but I couldnt help but notice consumption was considerably higher when it was 10+ as well (dropped .7 dKH in 24 hours compared to the typical .2-.3) so now I'm starting to second guess bringing it back down.
More intersting variables would be "why" and " are you reaching your goals using your target alk" ( ie better color or growth)?
Tbh, I picked 8.5 dkh because someone in my club who has amazing colors keeps his around 8.5. Also a couple other experienced reefers I trust stay in that range. I must have gotten lucky, because I am happy with the state of my 10 month old tank ( there, I totally jinxed myself)
I try to stay as close to 7 as I can with little variance where possible, with a preference for the higher side (0.3 either way at most).
SPS dominant mixed reef.
I try to control Alk variation more than worry about the value the system finds for itself. It averages around 8.0 using Kalkwasswer reactor and CO2-Calcium reactor along with outside air sourced aeration.
The system Alk varies with seasons in the year due to evaporation rate and also with the growth rate and periodic harvesting of corals on my mixed LPS / SPS population.
I'd be curious as to why a chosen number is targeted as well...color or growth? Is there a happy medium? I buy small frags predominately and based on a conversation with Jason Fox I've aimed for higher alk to optimize growth. Maybe later on when my tank has grown out I'll drop, in the meantime I hover around 9.5.