Mg consumption is way to much

[ArielS]

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?

 

[Lasse]

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?

I would go with this but send the samples directly after you have taken them. Do not wait 7 days with the first sample. And if you know the strength and amount of your Mg additive - then you do not need to stop dosing - you can back-calculate the demand

Sincerely Lasse

 

[Garf]

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?

Ok, you know all the standard responses by the looks of it, lol.
If your salinity is somehow decreasing by just 1% per day, that could cause it. There's a link to Randy's salinity DIY solution in my signature.

 

[Miami Reef]

You can store a bottled sample of tank water at the time of collection for the ICP, then once the results arrive, you can use your sample as a magnesium standard to assure the validity of the test kits.

I find it unusual for magnesium to fluctuate quickly on a day-by-day basis. Besides for salinity changes and poor test resolutions, I’m not sure what else could explain it.

 

[Lasse]

You can store a bottled sample of tank water at the time of collection for the ICP, then once the results arrive, you can use your sample as a magnesium standard to assure the validity of the test kits.

I find it unusual for magnesium to fluctuate quickly on a day-by-day basis. Besides for salinity changes and poor test resolutions, I’m not sure what else could explain it.

I know that sometimes the Mg consumption can be high because of forming of Mg and CO3 crystals, But this is often in the beginning with new sand and stones.

Sincerely Lasse

 

[Miami Reef]

I know that sometimes the Mg consumption can be high because of forming of Mg and CO3 crystals, But this is often in the beginning with new sand and stones.

Sincerely Lasse

Good point. I was thinking of that, too, but he didn’t mention a corresponding high alkalinity demand.

 

[ArielS]

I would go with this but send the samples directly after you have taken them. Do not wait 7 days with the first sample. And if you know the strength and amount of your Mg additive - then you do not need to stop dosing - you can back-calculate the demand

Sincerely Lasse

yes will try the ICP test. For now i use AF MG powder and make 20x than standard recomended mixing. If i use recomended dose i believe it will overflow my tank just to keep up the MG demand.

Let see what ICP

 

[Miami Reef]

yes will try the ICP test. For now i use AF MG powder and make 20x than standard recomended mixing. If i use recomended dose i believe it will overflow my tank just to keep up the MG demand.

Let see what ICP

My favorite ICP is Oceamo MS. It’s very accurate and IMO the best option if you’d like to store a sample for future testing.

 

[ArielS]

You can store a bottled sample of tank water at the time of collection for the ICP, then once the results arrive, you can use your sample as a magnesium standard to assure the validity of the test kits.

I find it unusual for magnesium to fluctuate quickly on a day-by-day basis. Besides for salinity changes and poor test resolutions, I’m not sure what else could explain it.

Okk. Yes i will store it and send the sample and do double check when got the result.

 

[ArielS]

My favorite ICP is Oceamo MS. It’s very accurate and IMO the best option if you’d like to store a sample for future testing. The results are highly accurate.

Im from indonesia and the available is AF ICP, send to the AF also took some time.

 

[Miami Reef]

Im from indonesia and the available is AF ICP, send to the AF also took some time.

Sounds good.

 

[BryanM]

It might help to know how the tank is stocked, though this is still pretty abnormal... I'm just throwing something out there.... ie, like coraline algae consuming alk, if a ton is present. So current stock, maybe a pic of the tank, might help with the odd edge case, if that's what we're dealing with.

 

[rtparty]

With a +-50ppm window with Mg test kits you can’t trust them

Nothing in the tank is consuming Mg at that rate.

 

[ArielS]

Yes man

With a +-50ppm window with Mg test kits you can’t trust them

Nothing in the tank is consuming Mg at that rate.

Yes many people said that.
Lets wait the ICP test result and see.

 

[rtparty]

Yes man

Yes many people said that.
Lets wait the ICP test result and see.

Many of us have already found and shown that ICP testing is far from perfect. In fact, I find they do far more harm than good for the vast majority of hobbyists.

 

[ArielS]

Yes man

Yes many people said that.
Lets wait the ICP test result and see.

Many of us have already found and shown that ICP testing is far from perfect. In fact, I find they do far more harm than good for the vast majority of hobbyists.

Yes, but no other choice. Lots of people said its impossible and always said its because faulty test kit. But i have use 3 different brand and tha result is not much different.


Other option is only check the CA and MG on local university Lab.

Which one better? do AF ICP to see whole result or i just need to check CA and MG from local university?

 

[Miami Reef]

But i have use 3 different brand and tha result is not much different.

Will the magnesium have a steady and consistent decline if you stopped dosing for a month?

 

[ArielS]

But i have use 3 different brand and tha result is not much different.

Will the magnesium have a steady and consistent decline if you stopped dosing for a month?

Per today i stop dosing MG. And will do check in 10 days.
In last 2 weeks i dose MG for 12ppm per day and check every 3 days the result is arround 1320-1350
I also just ask local university lab if they can do ICP test only for CA and MG. It can get result faster compare to AF ICP i need to send.

If i stop dosing in month could it be stress it my coral?

 

[Randy Holmes-Farley Verified Community Expert]

Yes, but no other choice. Lots of people said its impossible and always said its because faulty test kit. But i have use 3 different brand and tha result is not much different.


Other option is only check the CA and MG on local university Lab.

Which one better? do AF ICP to see whole result or i just need to check CA and MG from local university?

It is faulty tests before, or after, or faulty salinity control. There’s just no route for ongoing magnesium depletion. Where would it go?

 

[ArielS]

Yes, but no other choice. Lots of people said its impossible and always said its because faulty test kit. But i have use 3 different brand and tha result is not much different.


Other option is only check the CA and MG on local university Lab.

Which one better? do AF ICP to see whole result or i just need to check CA and MG from local university?

It is faulty tests before, or after, or faulty salinity control. There’s just no route for ongoing magnesium depletion. Where would it go?

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.