Ca / Mg Ratio?

[JohnnyTabasco]

Hey.
Can anyone tell me what the ratio should be. As I understand it, it's not really a problem to have high parameters if the ratio is spot on?

 

[hatrix11]

3.5mag/1calc

 

[JohnnyTabasco]

So if I had 470 Ca and 1350 Mg that would be a ratio of 2,8 and is too low?

 

[Anirban]

You are fine with that. Its not too low.

 

[JohnnyTabasco]

You are fine with that. Its not too low.

Thanks... What would you say is to low and too high...
I'm making a spreadsheet so I need some numbers for the "rule"...

 

[Anirban]

Lol...first rule is there is no rule. Its all demand and supply. But with Mg ideally 3 times the Ca amount is standard but I have seen people doing 2.5 time and they were all good. I think too low will be anything beyond that. As far high concern its pretty hard to get your Mg too high in the reef which will cause any damage. I have seen tanks with pretty high like 4 times the Ca value and they were all good.

 

[hatrix11]

There hasn't been many proven downsides to high calc, nor upsides. However it's said if mag gets too high (like 1700+) snails have trouble sticking to surfaces. I personally aim for calk 450, mag 1450, and alk at 9.

 

[Randy Holmes-Farley Verified Community Expert]

Hey.
Can anyone tell me what the ratio should be. As I understand it, it's not really a problem to have high parameters if the ratio is spot on?

No, they cannot (or should not), because the ratio should not be a goal. Just because one is high or low does not mean the other should be high or low.

They should be targeted to optimal values independently.

Calcium ought to be in the 400-550 mg/L range, and magnesium in the 1280-1400 mg/L range, IMO.

 

[JohnnyTabasco]

No, they cannot (or should not), because the ratio should not be a goal. Just because one is high or low does not mean the other should be high or low.

They should be targeted to optimal values independently.

Calcium ought to be in the 400-550 mg/L range, and magnesium in the 1280-1400 mg/L range, IMO.

Thanks for your input. I'm looking for the optimal ratio within toughs parameters
My main goal is to minimize precipitation. I run a BB tank without fish, but still get detritus.. And I read that could have to do with precipitation of calcium

 

[Randy Holmes-Farley Verified Community Expert]

Thanks for your input. I'm looking for the optimal ratio within toughs parameters
My main goal is to minimize precipitation. I run a BB tank without fish, but still get detritus.. And I read that could have to do with precipitation of calcium

Main ways to reduce precipitation are lower pH, lower alk, lower calcium/higher magnesium, and potentially lower temperatures. pH is the biggest driver.

A pH drop of 0.3 pH units is like halving alkalinity or calcium.

But in terms of magnesium alone, boost it to 1350-1450 ppm if that is a primary goal.

 

[JohnnyTabasco]

Main ways to reduce precipitation are lower pH, lower alk, lower calcium/higher magnesium, and potentially lower temperatures. pH is the biggest driver.

A pH drop of 0.3 pH units is like halving alkalinity or calcium.

But in terms of magnesium alone, boost it to 1350-1450 ppm if that is a primary goal.

Cool thanks.

 

[Randy Holmes-Farley Verified Community Expert]

Cool thanks.

You're welcome.

Happy Reefing.

 

[Brice Wagner]

Main ways to reduce precipitation are lower pH, lower alk, lower calcium/higher magnesium, and potentially lower temperatures. pH is the biggest driver.

A pH drop of 0.3 pH units is like halving alkalinity or calcium.

But in terms of magnesium alone, boost it to 1350-1450 ppm if that is a primary goal.

Greetings Randy,

I am a fellow chemist (analytical) and certainly not as versed in reef chemistry as you. I have a question about Ratio of Ca:Mg, not of concentration but of uptake. I know that this will widely dependent on coral but and I am simply looking for a starting point.

I currently dose 2 part : 28mL/day of 0.10 g/L Na2CO3 and 40mL/day of 329.82 g/L CaCl2. Last Tested Dkh 7, Ca 350 ppm

I would like to add more consistency with Mg instead of randomly dosing here and there. I would prefer to control it separately but I don't have the cash for a 2nd DOS at the moment. From my understanding I can create a solution of CaCl2 and MgCl2 but where to start; 2:1 by weight CaCl2 to MgCl2? These certainly shouldn't have solubility issues correct? Is this a silly idea altogether?

Thanks,

Brice

 

[Randy Holmes-Farley Verified Community Expert]

No solubility issues, but 2:1 is way too much magnesium. Demand is more like 1/10th of the calcium demand.

I discuss it here:

Reef Chemistry Question of the Day #198 Magnesium Consumption

Reef Chemistry Question of the Day # 198 In an aquarium where the alkalinity is depleted by 2.8 dKH and the calcium is depleted by 18 ppm each day, what would be the expected average magnesium depletion over a period of ten days? A. ~0.3 ppm per day B. ~1.2 ppm per day C. ~3.9 ppm per day...

www.reef2reef.com

 

[Brice Wagner]

No solubility issues, but 2:1 is way too much magnesium. Demand is more like 1/10th of the calcium demand.

I discuss it here:

Reef Chemistry Question of the Day #198 Magnesium Consumption

Reef Chemistry Question of the Day # 198 In an aquarium where the alkalinity is depleted by 2.8 dKH and the calcium is depleted by 18 ppm each day, what would be the expected average magnesium depletion over a period of ten days? A. ~0.3 ppm per day B. ~1.2 ppm per day C. ~3.9 ppm per day...

www.reef2reef.com

Thank you for the link. Im glad I asked and will guestimate low and work my way up to equilibrium.

Cheers!

 

[Randy Holmes-Farley Verified Community Expert]

Thank you for the link. Im glad I asked and will guestimate low and work my way up to equilibrium.

Cheers!

You’re welcome.

Happy Reefing!

 

[m5impact]

Sooo! If I was dosing Fritz RPM Calcium and Magnesium in a DOS what would the ratio be based on 2000ml

 

[Randy Holmes-Farley Verified Community Expert]

Sooo! If I was dosing Fritz RPM Calcium and Magnesium in a DOS what would the ratio be based on 2000ml

Welcome to Reef2Reef.

Have you measured to see if you need magnesium?

In general, you will probably consume the equivalent of 10-30x as much of the Fritch calcium as magnesium, but it depends on what exactly is consuming the alk and calcium. Coralline algae is a relatively larger user of magneisum than many corals.