Just a thought:
Would it be a bad idea to mix a dilute of muratic/sulfuric acid and RO/DI water and drip that in? Would that not reduce the alk and pH? As I understand it, the alk is just a measure of the ability to hold a pH. Also, how can having too much alk adversly effect life in the reef?
EDIT
dKH = 13.5
ca = 400
ph = 8.6
Tests were taken after adding a bit of tech-m was added. Just before the MH's turned on
High pH: Causes and Cures by Randy Holmes-Farley - Reefkeeping.com
URL = high pH, causes and cures. I think I'll give that a read before asking more questions