I've had a mixed reef going for well over a year now.
Tank - Waterbox Frag 105.4
Reef Octopus Skimmer
Full APEX system including Trident
Alk, CA, and Mg all stay pretty consistent through my Trident output:
Alk - 8.48
CA - 402
MG - 1332
Lighting up until recently consisted of 2 XR15 Blues...