Calcium Reactor and PH

I got a Calcium Reactor Easter weekend. Before this, my PH had been rock solid between 8.2-8.4 throughout the day/night. I was keeping my Alk around 11-12, I was just wanting something to keep my calcium and alk high so I didn't have to dump bottles of the stuff in constantly. I was expecting a dial in time, I was even expecting it to be weeks, what I wasn't expecting was this:

For the last 4 days or so, my PH has been in freefall in my main tank, taking a nosedive as low as 7.75, to the point I added Kalk to my ATO for the first time EVER to combat the situation.

At first, things went way too high ALK wise. I was/continue to test my Alk daily/every other day, keeping a close tab on things (But it's getting close to finals and I'm writing my thesis ) At one point it got as high as 14, so I dialed the reactor back SLIGHTLY. I'm trying to keep the effluent of the reactor around 6.7-6.8.

PH monitoring: I've got a cup catching the effluent with a ph probe hooked up to my Aquacontroller graphing and tracking it. Same with my system, PH to AC3.

CO2 I've been focusing on the reading from the ph of effluent. If it's too low, co2 goes down. Too high, co2 goes up to keep it in that 6.7-6.8 range.

Dripwise I've been trying to dial in using my alk tests. If alk in system falls too low, drip goes up SLIGHTLY, test hours later or even the next day, looking for that happy place where it will fall around 9-11 and hold steady so I don't ever have to touch it again. 1 drip a second, which seems to be the reccomended, sent my alk into freefall and it ended up around 6 the next day.

any ideas?

120 gallon tank with around 150 gallons actual, ASM g2 skimmer, Aquamedic 1000 calcium reactor, JBJ ATO, temp around 78,
Ammonia, Nitrate, Phosphate: 0
Nitrate: ~10ish
Alk 9 at last check (about 12 hours ago)
current PH: 7.94
effluent PH 6.94
Temp Currently 75, max 82 throughout the day

 

What reactor media are you using?

I am not familiar with an aquamedic calcium reactor. I know some reactors are difficult to tune.

 

The Caribsea ARM media. Standard stuff in the jar

 

Ok, the caribsea large ARM I use in my GEO I keep at 6.7 in the chamber. 6.9 may not be enough to really "melt" the media.

 

Great, I can up the Co2 and lower the PH in the chamber even more, but I'm more worried about the freefall of PH in my main tank....