Balanced Alkalinity/Calcium Tables

[Dr. Jim]

I know the general consensus is that it is not essential to perfectly match a particular calcium level with it's corresponding alkalinity measurement, but I'm wondering from where, and how, this table is derived....and, what is it's significance?

Also, even though it might be considered unnecessary to "chase numbers," would there be any benefit (even if just in theory) to actually having the calcium and alkalinity levels "match?"

 

[Moxtrain]

I find it interesting that pH isn't mentioned. That will change the balance numbers.

 

[Dr. Jim]

I find it interesting that pH isn't mentioned. That will change the balance numbers.

The table I posted above is from a D-D H2Ocean Salt brochure. I wonder if this table was tabulated for their particular salt that they claims mixes to pH 8.2-8.4?
I've seen other tables with slightly different calcium levels for a particular alkalinity level, so maybe the various tables were calculated based on different pH's??

 

[Randy Holmes-Farley Verified Community Expert]

The intent of balanced calcium and alkalinity IS NOT that they should ever be target levels.

What it means is that if you take normal seawater and add or subtract a balanced ratio of calcium or alkalinity (2.8 dKH of alkalinity for each 20 ppm of calcium), you can get to the values that are balanced.

That has some meaning, for example, in that if you start with normal seawater, you can get to any balanced levels by using a CaCO3/CO2 reactor, kalkwasser, or a two part with equal parts dosing, or by allowing corals to consume the alk and calcium.

So these are all balanced:

4.2 dKH 400 ppm calcium
7 dKH, 420 ppm
9.8 dKh, 440 ppm calcium
15.4 dKH, 480 ppm calcium

etc.

 

[Randy Holmes-Farley Verified Community Expert]

The table I posted above is from a D-D H2Ocean Salt brochure. I wonder if this table was tabulated for their particular salt that they claims mixes to pH 8.2-8.4?
I've seen other tables with slightly different calcium levels for a particular alkalinity level, so maybe the various tables were calculated based on different pH's??

pH wouldn't come into play.

 

[Dr. Jim]

The intent of balanced calcium and alkalinity IS NOT that they should ever be target levels.

What it means is that if you take normal seawater and add or subtract a balanced ratio of calcium or alkalinity (2.8 dKH of alkalinity for each 20 ppm of calcium), you can get to the values that are balanced.

That has some meaning, for example, in that if you start with normal seawater, you can get to any balanced levels by using a CaCO3/CO2 reactor, kalkwasser, or a two part with equal parts dosing, or by allowing corals to consume the alk and calcium.

So these are all balanced:

4.2 dKH 400 ppm calcium
7 dKH, 420 ppm
9.8 dKh, 440 ppm calcium
15.4 dKH, 480 ppm calcium

etc.

So by saying that "balanced calcium and alkalinity should not be target levels" are you suggesting that if the Alk is 7kH then Ca at 420 is NOT necessarily more desirable than 400 or 440 ppm (for maximum coral growth/health)?

4.2 dKH 400 ppm calcium
7 dKH, 420 ppm
9.8 dKh, 440 ppm calcium
15.4 dKH, 480 ppm calcium

I understand that "matching" the values is not essential...... just wondering if an "exact match" might be beneficial in any way.

Thank you!

 

[Randy Holmes-Farley Verified Community Expert]

So by saying that "balanced calcium and alkalinity should not be target levels" are you suggesting that if the Alk is 7kH then Ca at 420 is NOT necessarily more desirable than 400 or 440 ppm (for maximum coral growth/health)?

4.2 dKH 400 ppm calcium
7 dKH, 420 ppm
9.8 dKh, 440 ppm calcium
15.4 dKH, 480 ppm calcium

I understand that "matching" the values is not essential...... just wondering if an "exact match" might be beneficial in any way.

Thank you!

Right. Calcium level is quite unimportant to corals as long as its in the range of about 400 to 550 ppm.


And especially, " 4.2 dKH, 400 ppm calcium " may be perfectly balanced, but is not a good target.

 

[badger89]

I new to this am my Alk is at 151ppm and calcium is 479 how would i work out the balanced?

 

[Randy Holmes-Farley Verified Community Expert]

I new to this am my Alk is at 151ppm and calcium is 479 how would i work out the balanced?

See what I posted above:

"The intent of balanced calcium and alkalinity IS NOT that they should ever be target levels.:"

Your levels are fine and no changes are indicated for any reason. :)

 

[ReefWalker2]

The intent of balanced calcium and alkalinity IS NOT that they should ever be target levels.

What it means is that if you take normal seawater and add or subtract a balanced ratio of calcium or alkalinity (2.8 dKH of alkalinity for each 20 ppm of calcium), you can get to the values that are balanced.

That has some meaning, for example, in that if you start with normal seawater, you can get to any balanced levels by using a CaCO3/CO2 reactor, kalkwasser, or a two part with equal parts dosing, or by allowing corals to consume the alk and calcium.

So these are all balanced:

4.2 dKH 400 ppm calcium
7 dKH, 420 ppm
9.8 dKh, 440 ppm calcium
15.4 dKH, 480 ppm calcium

etc.

So if I understand you correctly, if for example I were to add a given amount of saturated Kalkwasser, or a Ca reactor drip rate, the ratio of increase of alkalinity and [Ca++] would be 2.8:20 (assuming no use by the tank inhabitants)? I wonder if you would have documentation on this? I can imagine a scenario whereby Alk X [Ca++] = Constant. Any deviation above that constant would give rise to CaCO3 precipitation (the solution would be supersaturated and unbalanced). One would only need to attempt values within that constant product to maximize saturation (and coral growth) without inducing precipitation.
Thank you

 

[Randy Holmes-Farley Verified Community Expert]

So if I understand you correctly, if for example I were to add a given amount of saturated Kalkwasser, or a Ca reactor drip rate, the ratio of increase of alkalinity and [Ca++] would be 2.8:20 (assuming no use by the tank inhabitants)? I wonder if you would have documentation on this? I can imagine a scenario whereby Alk X [Ca++] = Constant. Any deviation above that constant would give rise to CaCO3 precipitation (the solution would be supersaturated and unbalanced). One would only need to attempt values within that constant product to maximize saturation (and coral growth) without inducing precipitation.
Thank you

the ratio of alk and calcium provided by kalk comes from the chemical formula. It is calcium hydroxide, with one calcium ion for every two hydroxide ions. Mathematically, that causes the 2.8:20

A calcium carbonate reactor or a coral consumption ratio again comes from the chemical formula for calcium carbonate. One calcium ion to one carbonate ion, giving 2.8 to 20 ppm. The one caveat is that a small amount of other ions get into the structure in place of one of these. Magnesium is the most important of these. giving an actual known ratio of 2.8 to 18-20 ppm for all corals, coralline algae, and simple abiotic precipitation of calcium carbonate.

 

[ReefWalker2]

the ratio of alk and calcium provided by kalk comes from the chemical formula. It is calcium hydroxide, with one calcium ion for every two hydroxide ions. Mathematically, that causes the 2.8:20

A calcium carbonate reactor or a coral consumption ratio again comes from the chemical formula for calcium carbonate. One calcium ion to one carbonate ion, giving 2.8 to 20 ppm. The one caveat is that a small amount of other ions get into the structure in place of one of these. Magnesium is the most important of these. giving an actual known ratio of 2.8 to 18-20 ppm for all corals, coralline algae, and simple abiotic precipitation of calcium carbonate.

That makes sense. So if one were to add Calcium or Carbonate separately then it could cause precipitation because it is outside of that ratio (with the caveat of effect of other ions as you indicated)? Thank you for the explanation

 

[Randy Holmes-Farley Verified Community Expert]

That makes sense. So if one were to add Calcium or Carbonate separately then it could cause precipitation because it is outside of that ratio (with the caveat of effect of other ions as you indicated)? Thank you for the explanation

Precipitation happens when calcium, or more commonly, carbonate (via high alk and/or high pH) get too high. The ratio is not a factor. It’s really the multiplicative factor of calcium times carbonate getting too high.

 

[X-37B]

Precipitation happens when calcium, or more commonly, carbonate (via high alk and/or high pH) get too high. The ratio is not a factor. It’s really the multiplicative factor of calcium times carbonate getting too high.

Thought I would ask this here.
I run a carx.
Alk 7.5
Ca 545
Mag 1350
System uses 2.5 alk daily
Trying to understand how Ca got to 545.
System 150g's total
System is 14 months old running 150lbs live rock
I drip the effluent from my carx into a cylinder of bones @ ph of 6.5.
My nitrite reactor drips into same cylinder.
Tanks ca was 420 for 6 months.
Noticed it went to 480 and stayed there until I did an icp at one year.
Ca was 480 on mine 525 on ATI.
New icp showed 545 2 months later. My test showed 480. Noticed it was expired by 6 months, nice.
2 different new brands showed ca 525-530.
I have always ran an alk of 7-8max on previous carx systems and ca was always 420-450.
I slowed the carx down to almost off @ 3bpm.
I am dosing esv alk 2× a day until the Ca gets to 450 then I will adjust the carx.
No issues with the system but would like to understand how ca got so high.
No precipitation observed anywhere.
Thanks for taking the time to read this.

 

[Randy Holmes-Farley Verified Community Expert]

What media is in the reactor?

 

[X-37B]

What media is in the reactor?

Reborn large bones.

 

[Randy Holmes-Farley Verified Community Expert]

Coral skeleton media may contain more calcium per unit of alk than is being consumed in your tank. So if you use it to maintain alk, you may find that calcium rises over time.

That is because coralline and a few corals contain more magnesium and less calcium than does pure calcium carbonate (the magnesium swaps in for some of the calcium).

This is a known issue for folks using kalkwasser or AFR, and could be an issue with a reactor too.

 

[X-37B]

Coral skeleton media may contain more calcium per unit of alk than is being consumed in your tank. So if you use it to maintain alk, you may find that calcium rises over time.

That is because coralline and a few corals contain more magnesium and less calcium than does pure calcium carbonate (the magnesium swaps in for some of the calcium).

This is a known issue for folks using kalkwasser or AFR, and could be an issue with a reactor too.

Thanks for the explanation.
I alway have alot of coralline growth in my systems.
I will just monitor after it's adjusted and keep it below 500.