Is my tank using Mag over Alk?

[Faithbleed]

Hi Guys

I was having a discussion today with an experienced reefer and he seems to think my tank is using Mag instead of Alk are a primary component for building.

425XL reefer, 6 months old, reasonable stocking, few LPS and a few SPS frags.

I'm using Aquaforests DIY Balling method for dosing and I'm currently using 50mL of Calc, 45mL of ALk and 100mL of Mag.

My levels are 455, 7.45, and 1230. I don't test PH, I'm not sure what it is.

Growth is slower than I would expect it to be and I suspect it's due to low PH.

I use Red Sea's black bucket and have never been at their bucket stated levels (although I'm slowly trying to get there).

Is it possible to corals to consume mag over alk, which would account for my ever increasing mag requirement?

My reefer mate suggested stopping dosing mag to let it drop (not below 1150) in the hopes the corals will start consuming more alk and take it up as the primary building component.

Am I talking non-sense or is there any substance to this theory?

 

[Randy Holmes-Farley]

Hi Guys

I was having a discussion today with an experienced reefer and he seems to think my tank is using Mag instead of Alk are a primary component for building.

425XL reefer, 6 months old, reasonable stocking, few LPS and a few SPS frags.

I'm using Aquaforests DIY Balling method for dosing and I'm currently using 50mL of Calc, 45mL of ALk and 100mL of Mag.

My levels are 455, 7.45, and 1230. I don't test PH, I'm not sure what it is.

Growth is slower than I would expect it to be and I suspect it's due to low PH.

I use Red Sea's black bucket and have never been at their bucket stated levels (although I'm slowly trying to get there).

Is it possible to corals to consume mag over alk, which would account for my ever increasing mag requirement?

My reefer mate suggested stopping dosing mag to let it drop (not below 1150) in the hopes the corals will start consuming more alk and take it up as the primary building component.

Am I talking non-sense or is there any substance to this theory?

That is just not possible. Unless you have a mangrove that is dripping high magnesium salty water outside the aquarium, there is no sink for magnesium that does not involve a huge amount of consumed alkalinity for any magnesium consumed.

 

[Faithbleed]

Thanks heaps for the reply Randy!

No mangroves, just a lot of live rock and a shallow sand bed.

It's odd that of all the components Mag is being dosed twice as much as the others though right?

Do I just leave it dosing the current amounts and make small adjustments till I'm happy with my levels?

 

[piranhaman00]

Testing error is likely involved. Try new test kit or have someone else test it.

 

[Faithbleed]

Testing error is likely involved. Try new test kit or have someone else test it.

Theyre new kits from Aquaforest, so that seems unlikely, but ill see if i can get some secondary testing done.

 

[andrewey]

You might be cautious of taking chemistry advice from this reefer in the future

But seriously, I would investigate either A) testing error or B) your calculations with regard to either dosing or the concentrations of the magnesium supplement.

 

[Faithbleed]

You might be cautious of taking chemistry advice from this reefer in the future

But seriously, I would investigate either A) testing error or B) your calculations with regard to either dosing or the concentrations of the magnesium supplement.

The AF mag part is 10g of mag flakes and 25g of reef salt to 1L of water.

I might try lowering the dosing to equal levels for a few days and test daily to see what drops or needs topping up.

Just seems odd that mag usage is so high when its usually the other way around.

 

[andrewey]

Did you try double checking your magnesium results against another source before you make any changes? I don't know if you have a LFS or another hobbyist nearby, but that might be the cheapest/quickest way to get another data point without having to buy a second test kit.

 

[piranhaman00]

Theyre new kits from Aquaforest, so that seems unlikely, but ill see if i can get some secondary testing done.

Well your results are not possible so it is testing error.

 

[Faithbleed]

Well your results are not possible so it is testing error.

How do you mean not possible?

 

[andrewey]

Randy has some great articles about Magnesium if you are interested that go into the use and daily consumption rates. They might help answer your question as to why everyone is so certain you are not truly "consuming" that much magnesium and why there is an error somewhere.

Aquarium Chemistry: Magnesium In Reef Aquaria

This article details the nature of magnesium in seawater, how it is added, measured, and removed from marine aquaria, and how it impacts the maintenance of calcium and alkalinity.

reefs.com

 

[Randy Holmes-Farley]

Thanks heaps for the reply Randy!

No mangroves, just a lot of live rock and a shallow sand bed.

It's odd that of all the components Mag is being dosed twice as much as the others though right?

Do I just leave it dosing the current amounts and make small adjustments till I'm happy with my levels?

I'm not sure how much that really means. Part 3 is far weaker in concentration than the calcium part (in terms of calcium vs magnesium) , so using twice as much of it still means way less magnesium than calcium.

Magnesium is used at about 1/10th of the rate of calcium on a weight basis, but is somewhat variable based on exactly what organisms are depositing what type of skeleton (coralline algae, for example, deposits a mineral with more magnesium than most corals).

There is no way (with a hobby kit) to see the magnesium depletion on a day to day basis, and even after a week, it would be pretty hard to see.

When Aquaforest designed the product they put less than 1/10th as much magnesium in the part 3 than there is calcium in the calcium part. Thus you are still using WAY LESS magnesium than calcium.

That said, I also think testing error is a part of the "issue".