I have some mag chips that could be run in a reactor but I guess for it to be useful I probably ought to run a reactor. I just figure it's not worth dialing in a reactor on a tank that should be shutdown any day now. Yes, yes I know I'm slow on a tank build. It's been mentioned once or twice. People may think I don't notice but I notice.
But even still, I'm now starting to wonder if consumption can be significant. I always took the viewpoint that if my water change water was OK then my tank would be OK because I figured consumption was nowhere near that of Ca and Alk. But maybe not.
I guess the short answer is (if you were asking me that is, and sorry Doug for the hijack) I hope to find that out by testing my water change water. If it's high or normal then I know it is an issue of consumption that needs to be addressed with dosing (or a reactor that outputs Mg). Although I suspect a reactor with mag chips only "sort of" deals with replenishing Mg, I'm not sure you can really tune a reactor 2 ways - ie., one vectror to maintain Ca/Alk and another vector to maintain Mg - I would assume all 3 would be output proportional to one another so if Mg depletion isn't directly proportional to Ca and Alk depletion then it stands to reason you'd still have to occasionally do some correctional Mg dosing, or adjustments via water changes (ie., add Mg to makeup water to help elevate after a waterchange or whatever).
I will say that I'm surprised how much Mg it takes to raise the levels. Makes me wonder if there is indeed Mg consumption going on .. but I dunno ??