Mg consumption is way to much

ArielS

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Hello.
I have a very weird 45-gallon tank, about 18 months old. It was wiped out once because of BJD (when i go to holiday for 3 days) After that, I ran it as fish-only for around 3 months. Then, in early June, I did a 50% water change and started adding some corals again.

The magnesium consumption seems way too high in my opinion. At first, I suspected a test kit error, but I’ve used three different test kits (Salifert, Red Sea, and AF), and the results are pretty close.

Based on weekly testing, the average consumption is roughly:

Mg: about 10 ppm per day

Ca: about 2.5 ppm per day

KH: about 0.3 dKH per day


Some people say it’s impossible to have that much Mg consumption. have read the forum also many people said its test kit error — but it is what it is. 3 brand test kit all read close enough. I’ve checked multiple times to be sure. In past 2 month, I also tried stopping dosing for few days to see the consumption, did weekly water changes, and even went three weeks without any water change. The average consumption still stayed around the same numbers.

All my torch and bubble corals seem fine. Only my Goniopora sometimes doesn’t fully extend when I stop Mg dosing for a few days, which makes me believe the Mg is really being drain

Some of my friends say it’s impossible, debate MG only consume in certain number with KH And Ca And blablabla. Some say is ionic imbalance, Others say just follow what the tank needs — if it uses much Mg, then dose it.

For your information: during the first 6 months, my Ca rock steady without any dosing. The tank only consumed KH buffer and Mg, which I thought might be normal since it’s mostly LPS, so Ca demand is lower.

So my question is:
Should I just keep dosing based on what my tank consumes? (Even many says it impossible) or should I keep looking for the reason behind such high Mg consumption?

Have plan to Do ICP test (to make sure its not the test kit error)
What method you guys think i should use to check if the mg really drain much in my tank? stop dosing and take sample on first day and on day 7, and then send it?
 

Randy Holmes-Farley

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That what i try to find out since mid june. If test kit error, i try 3 different test kit. And also last 2 weeks i dose 12ppm per day to keep up with demand. Yesterday i do 10% water change test it and stop dosing and will wait for next 10 days.

If the MG still depleted that much i have no idea.
I wouldn’t believe it if it hadn’t happen in my tank.

How do you know your supplement is adding 12 ppm?
 
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JonasRoman

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Hello.
I have a very weird 45-gallon tank, about 18 months old. It was wiped out once because of BJD (when i go to holiday for 3 days) After that, I ran it as fish-only for around 3 months. Then, in early June, I did a 50% water change and started adding some corals again.

The magnesium consumption seems way too high in my opinion. At first, I suspected a test kit error, but I’ve used three different test kits (Salifert, Red Sea, and AF), and the results are pretty close.

Based on weekly testing, the average consumption is roughly:

Mg: about 10 ppm per day

Ca: about 2.5 ppm per day

KH: about 0.3 dKH per day


Some people say it’s impossible to have that much Mg consumption. have read the forum also many people said its test kit error — but it is what it is. 3 brand test kit all read close enough. I’ve checked multiple times to be sure. In past 2 month, I also tried stopping dosing for few days to see the consumption, did weekly water changes, and even went three weeks without any water change. The average consumption still stayed around the same numbers.

All my torch and bubble corals seem fine. Only my Goniopora sometimes doesn’t fully extend when I stop Mg dosing for a few days, which makes me believe the Mg is really being drain

Some of my friends say it’s impossible, debate MG only consume in certain number with KH And Ca And blablabla. Some say is ionic imbalance, Others say just follow what the tank needs — if it uses much Mg, then dose it.

For your information: during the first 6 months, my Ca rock steady without any dosing. The tank only consumed KH buffer and Mg, which I thought might be normal since it’s mostly LPS, so Ca demand is lower.

So my question is:
Should I just keep dosing based on what my tank consumes? (Even many says it impossible) or should I keep looking for the reason behind such high Mg consumption?

Have plan to Do ICP test (to make sure its not the test kit error)
What method you guys think i should use to check if the mg really drain much in my tank? stop dosing and take sample on first day and on day 7, and then send it?
Maybe late to the party and have not red all answers yet but Mg consumption by animals (corals etc) I say it's impossible. A coral consume 1% of Mg in ratio versus the Ca consumption. Calcareous algue 4%.
Mg is mostly "consumed" by adding to naked ca2co3 surfaces. Quite same as po4 can loosely add to same structures. It's coated by Mg and in that way prevent overprecipitation.
So if a lot of sand and rock, specifically if they haven't before been saturated , could absorb a lot of Mg. But sooner or later the process stop as its an equilibrium.
 
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