Magnesium up & Calcium down

[Alchameth]

Purchased a Trident during the holiday sale and noticed over the past 24 hours that my MG went up from 1255 to 1271, and during the same period my CAL went from 440 to 403. Meanwhile my ALK has been consistent 9.3 to 9.35

Rest of my parameters
Temp - 76-77.5
1.025
PH 7.9-8
NO3 - 2-5ppm
PO4 - 0

This tank has been up for only 3 months, but started with all the water and sand from my 90 and 32 biocube along with some bio media. The rock was removed, let to dry for a few weeks and put back in. No fish, but hermits, snails, urchin, cleaner shrimp and about 35 corals (all of which are happy and healthy looking).

I did a 25gal water change 5 days ago. Only thing I'm dosing is kalk, I did adjust my kalkstirrer 2 weeks back (setting it to run 15 minutes every time the ATO kicked on rather than mixing 24/7) when my ALK was over 9.5 and still rising. The ALK started trending down and has been stable for the past 5 days. The CAL I can see as a delayed result of my stirrer change, just no idea what could cause the MG to bump.

 

[YankeeTankee]

The trident like any testing device has a margin of error and the mg values are definitely within that plus you're only looking at 24 hours. I would wait a few days, see what results you get and if the trend continues then start brainstorming possible causes but with just 24 hours of data and the accuracy of our hobby grade testing equipment I don't think you need to start worrying yet unless you are seeing other troubling things happening in the tank. 1255 to 1271 is like, nothing.