Magnesium Fluctuation

[BayAreaReef408]

Hello everyone!

I am new to this from and just signed up. Happy to be a new member, this community looks awesome! Before I go into details about my question here are some specs for my tank.

-55 Gallon Mixed reef tank 48" wide.

Equipment
-Running for 2 years now and have abou close to 100 pounds of live rock
-Tank is not drilled and am using a 5 stage canister filter with chemipure blue and Purigen. Cleaned out every 2 weeks.
-Reef Octopus Skimmer
-Three little fishies phosphate reactor with rowa phos media
-Filter pads with Seachem Matrix bio media in canister filter
-Hang on refugium with live rock rubble and Chaeto
- two Jabao RW-8 wavemakers and another 800GPH powerhead
-PH probe
-300 Watt Heater
-Jabao automatic doser
-Auto Top off pump


Water paramters:
Salinity: between 1.025-1.026
Alk: 8.5-8.9
Calcium: 420ppm
Magnesium:1470ppm

Dosing:
-Potassium 3x a week
-Trace Elements twice a week
-Strontium 2x per week
-Iodine 1x per week
-Zeovit Pohls Xtra 4x a week
-Zeovit Coral booster 1x a week
-Zeovit Sponge power 2x week
-Zeovit coral vitalizer 3x week
-Zeovit LPS amino acid 3x per week
-Acropower 4x a week




My question is has anybody experienced a huge drop in magnesium consumption in my tank. My auto doser used to dose 40ml of mag a day, i checked leveled and they increased from 1375 to 1470. I stopped dosing for 2 days and it was still at 1470. I now dose 5 ml a day to keep it stable. Does anyone know why this is happening? Coraline algae is almost non existent as well due to my urchin.

 

[BayAreaReef408]

 

[BayAreaReef408]

 

[BayAreaReef408]

 

[ZoaCollector]

That fungia is bananas!

 

[BayAreaReef408]

haha thank you! it's one of my absolute favorites in my tank for sure.

 

[BayAreaReef408]

 

[BayAreaReef408]

I have stopped dosing mag for 2 days now and levels have not dropped unless I do water changes. I have never come across this issue. I iused to dose 40ml a day to keep it between 1375-1400

 

[Randy Holmes-Farley Verified Community Expert]

I have stopped dosing mag for 2 days now and levels have not dropped unless I do water changes. I have never come across this issue. I iused to dose 40ml a day to keep it between 1375-1400

And it shouldn't.

Magneisum depletion is very slow. Not more than 1-2 ppm per day in even the highest demand tanks. Often it is much less than 1 ppm per day. It is typically about 1/10 of the demand for calcium. Anything much above that is test kit error or due to water changes.

 

[sawdonkey]

I don't test Mg often because whenever I did, it was around 1350. Then my Hannah checker reagent was screwed up song thought I had an Alk issue. So I checked Mg and it was 1150. I don't know how long it took to drop 200 ppm. It could have been over a few months. I've been dosing it back up to 1350, but it takes an insane amount of Mg solution to increase the Mg in 250 gallons of water. I've put a whole gallon of BRS Mg in plus a whole bottle of Tech M and I'm still at 1300.

 

[BayAreaReef408]

And it shouldn't.

Magneisum depletion is very slow. Not more than 1-2 ppm per day in even the highest demand tanks. Often it is much less than 1 ppm per day. It is typically about 1/10 of the demand for calcium. Anything much above that is test kit error or due to water changes.

For my tank it has always been really fast. I use the Salifert kits and they have always been accurate. I used two different kits and they showed the same readings. am not dosing 5ml a day down from 40ml. It is just really odd to me to see such a huge decrease. I am thinking since i run a phosphate reactor with GFO it might be that the GFO media is done with and that took out a lot of the mag What do you think?

 

[Randy Holmes-Farley Verified Community Expert]

No, GFO doesn't take out magnesium nor does anything else significant aside from magnesium incorporation into calcium carbonate. There is just no other big sink (unless you grow tons of mangroves that are dripping salt from their leaves that lands outside the tank).

Trust me, I've been down this discussion road about magnesium lots (LOTS) of times. It is not truly depleting rapidly.

In no reef tank does magnesium EVER noticeably deplete in 2 days.

You said:

"My auto doser used to dose 40ml of mag a day, i checked leveled and they increased from 1375 to 1470."

Doesn't that make it sound like the 40 mL per day was overdosing so the levels were increasing?

 

[BayAreaReef408]

No, GFO doesn't take out magnesium nor does anything else significant aside from magnesium incorporation into calcium carbonate. There is just no other big sink (unless you grow tons of mangroves that are dripping salt from their leaves that lands outside the tank).

Trust me, I've been down this discussion road about magnesium lots (LOTS) of times. It is not truly depleting rapidly.

In no reef tank does magnesium EVER noticeably deplete in 2 days.

You said:

"My auto doser used to dose 40ml of mag a day, i checked leveled and they increased from 1375 to 1470."

Doesn't that make it sound like the 40 mL per day was overdosing so the levels were increasing?

That 40ml a day kept my levels stable for months, it was only recently where t increased significantly and I find myself not needing to dose much if any at all. I was just wondering what could have caused this.

 

[Randy Holmes-Farley Verified Community Expert]

That 40ml a day kept my levels stable for months, it was only recently where t increased significantly and I find myself not needing to dose much if any at all. I was just wondering what could have caused this.

What magnesium product were you using?

If it was like my DIY (as from BRS) in potency, then 40 mL per day is about 9 ppm per day in 55 gallons of water volume. Most commercial products are even higher. There's no way the demand was that high, but you might have been offsetting lower magnesium in the water change water.

FWIW, a change in specific gravity from 1.025 to 1.026 will cause a change in magnesium from, say, 1300 ppm to 1350 ppm, so changes in the salinity of the tank may also be confounding the issue a bit.

Finally, test kit inaccuracy is most frequently the problem in reported fluctuating magnesium levels.

 

[BayAreaReef408]

What magnesium product were you using?

If it was like my DIY (as from BRS) in potency, then 40 mL per day is about 9 ppm per day in 55 gallons of water volume. Most commercial products are even higher. There's no way the demand was that high, but you might have been offsetting lower magnesium in the water change water.

FWIW, a change in specific gravity from 1.025 to 1.026 will cause a change in magnesium from, say, 1300 ppm to 1350 ppm, so changes in the salinity of the tank may also be confounding the issue a bit.

Finally, test kit inaccuracy is most frequently the problem in reported fluctuating magnesium levels.

Good info here! I did not know that. I use the Kent Marine tech M Mag supplement.

 

[Randy Holmes-Farley Verified Community Expert]

That would be adding abut 14 ppm magnesium per day in 55 gallons of total water.

To really consume that much, you'd need to also consume something on the order of 126 ppm of calcium and 18 dKH of alkalinity every day, and that assumes the highest magnesium incorporation rates that only some corals can attain.

 

[BayAreaReef408]

right now I am dosing a part A and part B alk and calcium solution. I am on a 12 hour dosing cycle and dose 3ml part A and part B every hour for a total of 36 ml of alk and calcium a day. This keeps my alk between 8.5-8.9 and my calcium between 410-420

 

[BayAreaReef408]

right now I am dosing a part A and part B alk and calcium solution. I am on a 12 hour dosing cycle and dose 3ml part A and part B every hour for a total of 36 ml of alk and calcium a day. This keeps my alk between 8.5-8.9 and my calcium between 410-420

 

[BayAreaReef408]

That would be adding abut 14 ppm magnesium per day in 55 gallons of total water.

To really consume that much, you'd need to also consume something on the order of 126 ppm of calcium and 18 dKH of alkalinity every day, and that assumes the highest magnesium incorporation rates that only some corals can attain.

Sorry for the same messages, trying to figure out how to quote.

right now I am dosing a part A and part B alk and calcium solution. I am on a 12 hour dosing cycle and dose 3ml part A and part B every hour for a total of 36 ml of alk and calcium a day. This keeps my alk between 8.5-8.9 and my calcium between 410-420

 

[Randy Holmes-Farley Verified Community Expert]

Part A and B of what brand?

Assuming it is my DIY (like BRS sells) that 36 mL of alkalinity additive is equivalent to a bit less than 1 dKH per day, which is certainly reasonable but won't noticeably impact magnesium for a substantial period of non dosing.