Just say NO to magnesium testing: RMM is born

[Garf]

Is it possible to reach a coral biomass that processes ammonia at a rate it outcompetes nitrifying bacteria to the point they are no longer present (or kept at very low levels)?

Maybe, Wrong thread? Lol.

 

[TokenReefer]

Maybe, Wrong thread? Lol.

Yup! Lol idk what happened there

 

[Randy Holmes-Farley]

If magnesium is often held at three times calcium then wouldn’t it reduce by three times calcium consumption?

I have never recommended that, and even if true, no. Consumption is not based on the concentration.

 

[Randy Holmes-Farley]

Is it possible to reach a coral biomass that processes ammonia at a rate it outcompetes nitrifying bacteria to the point they are no longer present (or kept at very low levels)?

Maybe.

 

[GARRIGA]

Is it possible to reach a coral biomass that processes ammonia at a rate it outcompetes nitrifying bacteria to the point they are no longer present (or kept at very low levels)?

Wouldn’t you need a bare tank absent biological media in the sump as well to allow that otherwise reefs would likely be devoid of bacteria and at the speed they replicate can’t see corals out competing nature’s waste disposal system.

 

[TokenReefer]

Wouldn’t you need a bare tank absent biological media in the sump as well to allow that otherwise reefs would likely be devoid of bacteria and at the speed they replicate can’t see corals out competing nature’s waste disposal system.

Wrong thread to be fair but yes I think it'd be difficult but I think bacteria needs a ramp up time to reach an affective mass (I could be wrong) and corals may not? Volume of water/ surface area may be a factor. Much quicker for small tanks to get coated in bacteria for instance. Idk just spitballin.

I heard someone say they did an aquabiomics and they found no nitrifying bacteria. I thought it was odd and at first thought it was clearly a testing error but their tank was packed to the brim with corals and plumbed into other frag tanks all brimming with coral. So maybe?

 

[dr_vinnie_boombatz]

@Randy Holmes-Farley I had an ATI ICP on 7/6 and another on 8/6. I've kept any dosing of Mg to 16% of Ca plus weekly 12% WCs but am showing Mg going from 1331 to 1261. Is this a testing error? Should I dose extra Mg or wait until another ICP? Ca went from 433 to 423. Salt mix has 1311 mag per RS ICP @ bucket shows 1310. Thank you!

 

[Randy Holmes-Farley]

@Randy Holmes-Farley I had an ATI ICP on 7/6 and another on 8/6. I've kept any dosing of Mg to 16% of Ca plus weekly 12% WCs but am showing Mg going from 1331 to 1261. Is this a testing error? Should I dose extra Mg or wait until another ICP? Ca went from 433 to 423. Salt mix has 1311 mag per RS ICP @ bucket shows 1310. Thank you!

Do you have the salinity values from the icp company on those days?

How much actual calcium was dosed during this time (ppm per day)?

 

[rhitee93]

OK, I've been struggling for a couple of weeks to figure this one out. I know the answer is in here somewhere, but I'm missing it for some reason.

How much calcium is in a liter of saturated limewater?

My tank has evolved to where I needed to start dosing to maintain alkalinity and calcium and I have chosen saturated limewater/kalk to do this. After a few weeks of making slow adjustments, it appears I have figured out the right dose to meet the demand. (1.73 L/day currently)

Now all I need is to understand how much calcium that is so I can add a weekly dose of magnesium to match.


Edit: I guess I needed to post this to clear out my google-foo cobwebs. One final hail-mary search attempt found exactly what I have been looking for all this time:
https://www.reef2reef.com/threads/fully-saturated-kalkwasser-and-magnesium.689440/post-7069722

TLDR: RHF states that if you want to follow a 10:1 ratio between Ca and Mg, you should add 17ml of his DIY magnesium mix for every 10L of saturated kalkwasser.

 

[slythy]

That is my recipe, which is designed for FIXED part 3 dosing, not measurement based dosing of magnesium.

An Improved Do-it-Yourself Two-Part Calcium and Alkalinity Supplement System by Randy Holmes-Farley - Reefkeeping.com

You dose 1 mL of the third part for each 6.2 mL of the calcium part.

@Randy Holmes-Farley

I dose 1 gallon of Kalk a day and dose 35ml of your 2 part calcium on top of that in my 280gallon system

using this I am dosing about 4.25 PPM of calcium a day, which equates to ~122ml of pure 2 part. Dividing that by 6.2 = ~19.7 ml of magnesium/day.

Does that seem right?

Thanks,

 

[Randy Holmes-Farley]

OK, I've been struggling for a couple of weeks to figure this one out. I know the answer is in here somewhere, but I'm missing it for some reason.

How much calcium is in a liter of saturated limewater?

My tank has evolved to where I needed to start dosing to maintain alkalinity and calcium and I have chosen saturated limewater/kalk to do this. After a few weeks of making slow adjustments, it appears I have figured out the right dose to meet the demand. (1.73 L/day currently)

Now all I need is to understand how much calcium that is so I can add a weekly dose of magnesium to match.


Edit: I guess I needed to post this to clear out my google-foo cobwebs. One final hail-mary search attempt found exactly what I have been looking for all this time:
https://www.reef2reef.com/threads/fully-saturated-kalkwasser-and-magnesium.689440/post-7069722

TLDR: RHF states that if you want to follow a 10:1 ratio between Ca and Mg, you should add 17ml of his DIY magnesium mix for every 10L of saturated kalkwasser.

Saturated kalkwasser is 808 ppm calcium at 25 deg C. You can use this calculator to see what it is adding;

Reef Chemistry Calculator

reef.diesyst.com

 

[Randy Holmes-Farley]

@Randy Holmes-Farley

I dose 1 gallon of Kalk a day and dose 35ml of your 2 part calcium on top of that in my 280gallon system

using this I am dosing about 4.25 PPM of calcium a day, which equates to ~122ml of pure 2 part. Dividing that by 6.2 = ~19.7 ml of magnesium/day.

Does that seem right?

Thanks,

Using the calculator linked above, the kalk is adding 3 ppm and the two part is adding 1.3 ppm.

To get 0.4 ppm of magnesium using my diy recipes, you need 9 mL of the mag part.

But it’s a bit more complicated when using a two part since you also need to account for salinity corrections due that part of it, but not for the kalk part.

I’d follow my recipe exactly for the two part (610 mL of mag part per gallon of calcium used, in this case that means 6 mL per day) and add to that the mag for the kalk part, being 0.3 ppm per day or 6.8 mL per day. Total 12.8 mL per day.

 

[jonelder68]

@Randy Holmes-Farley when dosing kalk would your recipe for 3 part balling #1 or #2 dosage for magnesium be a valid dosage? Either the 2.7% or 5.4%? Since testing is not accurate I’ve been questioning how to maintain magnesium with kalk?

 

[Randy Holmes-Farley]

@Randy Holmes-Farley when dosing kalk would your recipe for 3 part balling #1 or #2 dosage for magnesium be a valid dosage? Either the 2.7% or 5.4%? Since testing is not accurate I’ve been questioning how to maintain magnesium with kalk?

This is a perfect case to dose magnesium at 5-10% of the calcium dosed, using my diy, or other magnesium product. If coralline is a big part of demand, go with 10%. If not, go with 5%.

 

[jonelder68]

This is a perfect case to dose magnesium at 5-10% of the calcium dosed, using my diy, or other magnesium product. If coralline is a big part of demand, go with 10%. If not, go with 5%.

Perfect! Thanks as always Randy

 

[Randy Holmes-Farley]

Perfect! Thanks as always Randy

You’re welcome.

Happy Reefing!

 

[jeremie]

1. Valuable Nutrients from Ulva rigida: Modulation by Seasonal and Cultivation Factors
2. MINERAL BALANCE OF AN INVASIVE ALGA CAULERPA RACEMOSA VAR. CYLINDRACEA ON THE COAST WEST OF ALGERIA

Although there are differences between species, it seems that some macroalgae accumulate a significant amount of magnesium in their tissue. Therefore, I'm not entirely convinced that the impact of algae filters can be ignored.

Using the second paper as an example, it was demonstrated that the magnesium content in Ulva rigida varies from approximately 3000 mg to 4000 mg per 100 g of dry algae across different seasons.

This means that if you grow 100 g (dry weight) of Ulva rigida in a 400 L tank, the algae could also take in 7.5 to 10 mg/L of magnesium.

Thus, it seems possible to achieve an uptake ratio higher than the 1:10 limit in a system with a lower calcification rate and high algae density, assuming I haven't misunderstood the papers or miscalculated.

Any thoughts?

 

[Randy Holmes-Farley]

1. Valuable Nutrients from Ulva rigida: Modulation by Seasonal and Cultivation Factors
2. MINERAL BALANCE OF AN INVASIVE ALGA CAULERPA RACEMOSA VAR. CYLINDRACEA ON THE COAST WEST OF ALGERIA

Although there are differences between species, it seems that some macroalgae accumulate a significant amount of magnesium in their tissue. Therefore, I'm not entirely convinced that the impact of algae filters can be ignored.

Using the second paper as an example, it was demonstrated that the magnesium content in Ulva rigida varies from approximately 3000 mg to 4000 mg per 100 g of dry algae across different seasons.

This means that if you grow 100 g (dry weight) of Ulva rigida in a 400 L tank, the algae could also take in 7.5 to 10 mg/L of magnesium.

Thus, it seems possible to achieve an uptake ratio higher than the 1:10 limit in a system with a lower calcification rate and high algae density, assuming I haven't misunderstood the papers or miscalculated.

Any thoughts?

It’s possible, yes, and worth keeping in mind. It is certainly true that some macroalgae contain substantial magnesium, and that can skew the ratios in the water. In practice in ordinary reef tanks, however, it does not seem to be causing significant issues based on what folks report happening in their aquaria.

The paper you posted shows 3000 mg Mg per 100 g dry weight. Ulva rigida is about 76% moisture, so that translates to 3000 mg per 417 grams actual macroalgae.

If a 100 gallon tank harvested 417 grams of that macroalgae each 10 days, that would export 3,000 mg of magnesium, and when you replace that lost volume with more seawater (to maintain salinity), that adds back about 542 mg of Mg. Thus, there is a net loss of 2,458 mg of Mg. In 100 gallons (379 L), that corresponds to 6.5 ppm in 10 days.

If the same tank was calcifying at a rate of 2 dKH per day, it would consume about 14 ppm of calcium per day, or 140 ppm per 10 days. The RMM magnesium amount to dose would be 7-14 ppm magnesium.

Thus the amount of magnesium could be significant if one harvested that much ulva rigida, and if doing so, I would one should elect the higher end of the range recommended, or even somewhat higher if calcification is low or coralline is the main user.

 

[taricha]

Recently I did a round of water testing, home and multiple ICPs after an extended time (months) of very little water changes ~1-2% per week and only limewater supplementation.

Yes, Ca drifted high and Mg drifted lower than what I would target. But neither got to actually problematic levels.
Just another data point that with modest water changes - unlike my very small ones it's highly unlikely for Mg to drift enough to cause problems.
And you'll be OK not testing it.

 

[Randy Holmes-Farley]

Recently I did a round of water testing, home and multiple ICPs after an extended time (months) of very little water changes ~1-2% per week and only limewater supplementation.

Yes, Ca drifted high and Mg drifted lower than what I would target. But neither got to actually problematic levels.
Just another data point that with modest water changes - unlike my very small ones it's highly unlikely for Mg to drift enough to cause problems.
And you'll be OK not testing it.

Thanks for the data, taricha.