$$$, and a cya for accuracy. But we are looking at trends, not absolutes for our tanks. We care if the dKh is moving, not that it is exactly 9.2 vs 9.8
The old chasing numbers vs. trends and observation argument still sticks
I’d prefer both. In my experience it’s hard to know if a reading is drifting in accuracy, vs my tank is actually drifting and I need to change my dosing, or a combination of both. If it’s fairly accurate and reasonably reproducible and I can trust the numbers it’s much less aggravating.
Also if it tells me 9.2 one day and 9.8 the next I have to choose between getting worried and retesting (which I do if I trust the test) vs losing faith in it and ignoring (like I do with the conductivity probe for example).
I’ve had things slowly drift and wind up being a problem, like for example the pH probe. You can be confident it isn’t changing much per day so it feels like your trend is fine, but over time it can drift dangerously.
I think the ”cool kid” argument to not chase numbers is basically misguided. People use the straw man argument to not chase numbers down to tiny decimal places and overreact, hurting your tank. Well, ok duh. But knowing the real value for your salinity, alkalinity, temperature, etc is actually important in my opinion. If they get significantly out of range you should be chasing those numbers back to the normal range before your coral, inverts, fish are dying or showing signs of stress as seen with observation. Even doing everything right this is a challenging hobby, why not put effort into getting accurate lab values if you can?
I don’t have any experience with the knockoff ABC reagents, I’m not saying they aren’t good or anything.