Week 5 flower update, chasing a cal-mag lockout

Running a DWC setup in my 4x4 right now, five weeks into flower on a Zkittlez cut i've had for two cycles. Reservoir temps sitting at 67F, pH locked in at 5.85, and i'm pushing 1,150 ppm (800 scale) with a base nutrient mix plus cal-mag and a PK booster. Growth has been stacking nicely but around day 32 I started seeing interveinal chlorosis creeping up on mid-canopy leaves, classic calcium deficiency presentation even though my numbers looked correct on paper.

Turned out my cal-mag was underdosed relative to the RO water I switched to mid-run. I was mixing at 5ml per gallon but RO strips everything, so I bumped to 8ml per gallon and recalculated my base EC to compensate, ending up at 1.9 EC total. Within five days the new growth came in clean. Older affected leaves didn't recover, but the damage stopped spreading, which is the goal.

One thing I'm keeping an eye on is root zone DO. Denver sits at 5,280 feet and dissolved oxygen saturation in water is lower at altitude than at sea level for the same temperature. I'm running two air stones but I've been wondering if I'm actually hitting adequate DO or if i'm compensating for something I can't easily measure without a DO meter.

Anyone here running DWC at altitude, or had a mid-run RO switch cause a similar lockout? Curious if the 8ml cal-mag per gallon sounds right to others or if I'm still leaving something on the table.