Magnesium dosing, stopped dosing not dropping

[Dlealrious]

Hi all
I was wondering if once there is enough magnesium in your tank do you need to stop/reduce dosing. I was dosing about 40ml a day to get up to 1500(thought i had bryopsis). Done 1/3 water change and it came down to 1430. Since wc i turned off doser but mag hasnt dropped in 4 weeks.
7 month old sps tank with mainly frags. Ca 425 kh 7.5-7.8
I dont normally do wc only did to reduce mag.

 

[Breadman03]

Mag is used very slowly, so don’t expect it to drop like alk does.

 

[Dlealrious]

Was thinking once you have enough it holds. I remember before getting upto 1350 seemed like a had to dose so much to get there

 

[Clownfishy]

That is interesting, I have to continually add Magnesium yet Alk and Calcium are maintained through weekly waters changes using reef crystals salt and kalkwasser. I wonder if different corals use different amounts of these elements?

 

[Dlealrious]

I was thinking maybe once mag gets to a certain point it stays there. When i was 1480 1500 it just sat there for weeks without going up at 40ml. Now its staying stiĺl not going down with no addition. I know its not taken up like ca kh bit was kind of wondering if i keep dosing say 10ml and it doesnt change am I just wasting mag solution?

 

[Randy Holmes-Farley Verified Community Expert]

Was thinking once you have enough it holds. I remember before getting upto 1350 seemed like a had to dose so much to get there

No, higher magnesium will make it drop even faster, but the demand is not more than about 1/10th of the calcium decline and so is typically about 1 ppm per day. If you are hundreds of ppm above normal, it will obviously take a very long time to drop to normal.

 

[Randy Holmes-Farley Verified Community Expert]

I was thinking maybe once mag gets to a certain point it stays there. When i was 1480 1500 it just sat there for weeks without going up at 40ml. Now its staying stiĺl not going down with no addition. I know its not taken up like ca kh bit was kind of wondering if i keep dosing say 10ml and it doesnt change am I just wasting mag solution?

No. [emoji3]

 

[Dlealrious]

Ah thanks randy i will see how it goes for another few weeks and then start dosing a little bit again.

 

[Randy Holmes-Farley Verified Community Expert]

You're welcome.

let's us know how it works out.