my Mg never been decrease..

[kamkam1999]

HI everyone, since i moved to the new 3 ft SPS tank 4 months, i have lots of SPS and have kamore CMK to check ca mg kh, however my mg is still in 1380-1420 and i have never dose any about mg, i have dosing KH for 200ml/day CA for 27ml/Day, and CA 450 MG 1400 KH 7.6. why would this happened? please help:loudly-crying-face:

i have used Hanna, Aquaforest test kit, salifert test kit, all showed same value

 

[kamkam1999]

i do 5% water changes every week, using aquaforest reef salt+ at 1.026-1.027

 

[Randy Holmes-Farley Verified Community Expert]

Magnesium is super slow to deplete.

 

[kamkam1999]

Magnesium is super slow to deplete.

is it normal? because my frirends' Mg drop really fast

 

[Randy Holmes-Farley Verified Community Expert]

is it normal? because my frirends' Mg drop really fast

Really fast is test error. Magnesium test error is so common that I do not recommend even testing it. I recommend just dosing it based on calcium demand.

https://www.reef2reef.com/threads/just-say-no-to-magnesium-testing-rmm-is-born.1017528/
Magnesium never depletes faster than about 1/10th of the calcium depletion rate. Sometimes much slower.

Coralline algae is a big user, and gives that 1/10th rate. Some corals incorporate relative little magneisum and the relative rate is much lower.