Well .. consider the history though, this tank doesn't particularly behave in typical kinds of ways. Water changes also are happening, but currently at a rate of about maybe 8% per week. I sourced me a bigger bucket, 55gal, which should make it more like 15% per week but I have to revamp the room to make this thing fit in there. So for now water changes are possibly too small. Next, considering that the tank was humming along in steady state until a couple months ago and suddenly the Ca depletion rates stopped, so I had to back off the Ca dosing quite a bit to remain at targets. Fast forward another couple months and during that time trying to reduce phosphates, is it possible the Ca consumption started up again and I missed the point at where it started to drop? But that would be a bit unexpected because although the tank LOOKS better (way less hair algae, corals look better, evidence of growth in some corals, etc.) the PO4 test reading is still pretty high (0.18 tonight). Unfortunately there's no reason to suspect testing error on the PO4 as the checker gives a zero reading on the FOWLR (there's irony for you. The lesson learned is "stop caring about parameters" I think.)
All conjecture until I can get a confirmation of one or the other Ca readings, I guess. I finished off the Salifert tonight anyhow so due for a new test kit. I might as well try a checker, they're only $20 more than the Salifert, and as for Elos .. I like them but this is not the first time I've taken home a test kit only to discover the expiry date being in the past after I remove the SKU. Maybe it's fine past the expiry to a certain point but who knows how long.