Recent alk dosing/consumption confusion. Suggestions/thoughts?

[zack801]

So about a week ago i switched from using Seachem reef fusion1/2 to ESV b-ionic. I kept the same dosage for alk/calcium at 32ml/day for each. I've been testing alk every day just to keep an eye on things and everything has been stable. That was until yesterday... Normally im around 8.2-8-5 dkh but yesterday it had dropped all the way to 7.11-7.23 out of the blue. I tested the day before and alk was still in its normaly 8.2-8.5 range. I kept an eye on my doser as it doses each hour. Nothing was clogged and it was dosing as expected. So to correct the lower alk i raised my dosing up last night and found it this morning at 9.1 dkh... I turned off my pump for two hours to let it drop a bit and measured again it was all the way back down to 7.84dkh... Something seems off to me. Im using a Hanna alk checker and the same bottle of reagent for each test. Does anyone have any ideas? Up until now my alk has been pretty solid. This tank is mostly acros and im a bit concerned by this type of swing since i haven't had one before.

 

[zack801]

Other parameters:
Ph: 8.15
Cal: 465
Mag: 1425ppm
Nitrate: 2ppm
Phos: .01ppm

 

[zack801]

According to http://reef.diesyst.com/chemcalc/chemcalc.html for me to even raise my dkh from 7.23 - 9.1dkh it would have needed 427ml of alk. i only dosed 40ml (increased from 30ml to raise it to my normal levels) so im confused how it actually raised that high. multiple tests with the same checker and reagent that i've been using the last couple of weeks. Could esv b- ionic be that inconsistent?