I don't think that there really is a proper Alk... Pick a number and don't let it move, corals can adapt to various water conditions. My tank seems to like it around 7.7-8.0 and I still get fantastic growth! I personally don't see a need to run alk over 8, just less for me to dose saving money, corals still grow fast and color seems to be better when I run my tank lower not to mention its safer to run a lower alk as things don't go sideways quite as quick..