alk and ca balance

[mfinn]

As I understand it, the alk and ca balance can be disrupted by low mag.

So, if my ca is 430 and my alk is 10.6 and the mag is 1050.
What is going to happen when I add enough mag to raise it up to 1300 -1350.
Is the calcium going to raise or is the alkalinity going to drop?

I am dripping kalkwasser in my topoff water.

 

[BeakerBob]

You might see a very slight decrease in alkalinity, but it will not be significant. I don't think you will see any change in the calcium.

 

[mfinn]

I was hoping the change would be on the alk side as it is a little high.
Does something need to be done to lower it?

 

[BeakerBob]

Are you currently dosing Alk & Ca?

 

[SteezySPS]

i thought mag helps increase alk or am I wrong?

 

[mfinn]

Are you currently dosing Alk & Ca?

Just kalkwasser in my topoff water.

 

[SteezySPS]

As I understand it, the alk and ca balance can be disrupted by low mag.

So, if my ca is 430 and my alk is 10.6 and the mag is 1050.
What is going to happen when I add enough mag to raise it up to 1300 -1350.
Is the calcium going to raise or is the alkalinity going to drop?

I am dripping kalkwasser in my topoff water.

I read somewhere that mag helps increase alk and mag by decreasing precipitation? not sure. you should google reef chemistry calculator and the links will help you figure out how much needs to be dosed for all three to keep the levels you want.

 

[BeakerBob]

The addition of Magnesium into the tank at high levels will cause a thin layer of magnesium carbonate to form over calcium carbonate. This layer slows down the deposition of calcium carbonate. This alone does not increase calcium or alkalinity, but the continued addition of a two-part dosing or kalkwasser will cause an increase.

I would suggest that if you want to increase the magnesium concentration in your tank, decrease your Kalk supplementation by half and test after a week or two when it has stabilized.

Do you have a lot of actively growing sps corals?

 

[mfinn]

Do you have a lot of actively growing sps corals?

This tank has mostly branching LPS and encrusting monti's

 

[lpslover]

This would be the issue with kalk. In my experience it tends to crash Mg levels. Trying to keep my Mg at even 1200 was requiring bottles and bottles of Mg supplement. Not sure about the chemistry behind why. Perhaps BeakerBob can illuminate that. I've switched to BRS Recipe 1 Two (Three) Part.

I do still use Kalkwasser for weekly supplemental dosing to make up the difference between the amount of two part needed to maintain the Alk and Mg and the amount of Ca the tank is running through. This way I not only make up the calcium shortage, but I get the nice buffer reset and increased pH at the same time.

 

[mcarroll]

I read somewhere that mag helps increase alk and mag by decreasing precipitation? not sure. you should google reef chemistry calculator and the links will help you figure out how much needs to be dosed for all three to keep the levels you want.

I think a better way to say it is that precipitation of calcium with carbonates is more likely without the presences of adequate magnesium to get in the way. In other words, if you were to make a big dose of Alk while Mg is low, you could be in for a precipitation event. If your Mg were at normal levels, the same alk dose would not be an issue.

-Matt