Magnesium 1600-1700 issue?

[Spar]

I have always maintained magnesium between 1350-1450. I had a salifert kit that I was relying on showing 1350, and even a red sea kit that showed around 1350 also. the salifert kit was almost empty when getting those readings. the red sea kit was several years old.

i have since ordered two new salifert kits (expiry dates are 3 months apart, so different batches of product). each is reading around at 1600. which makes me think that Mg has actually been much higher than I had been getting test results at.

this would mean that I have been maintaining Mg btw 1600-1700 for the past few months.

The only unexplained issue in my tank lately is that my coralline algae has whited out. coral (acros/montis mostly) are mostly doing just fine.

could that 1600-1700 range be causing any other issues? or could it be the problem with the coralline also?

For reference, Ca is at 420 and KH at 8.75 dKH.

[bertoni]

My best guess is that 160-1700 ppm is safe enough. Lots of people run tanks with the magnesium high to try to kill Bryopsis, and they don't seem to have any problems. You could try some water changes to try to lower the level, though. Test kits tend to read lower over time as the water from the reagents evaporates. Keeping the vials closed as much as possible should help a bit.