Question with dosing Magnesium

[FreshSaltyGuy]

Hello all,

Need some help on doing magnesium. My 250 gal total volume tank is low on Mag @ 1120. I bought some Reef Adva tage Magnesium and read the instructions. I also used the Reef Chemistry Calculator below and it shows to add 93oz.
Here are my question if someone can help guide me I'd appreciate it. Can I add the full 93oz to my ATO since it only adds water a few times a day, but I also added Kalkwasser to my ATO...can I put both in the same thing?
If not how much would the concentrate be if I mix that amount 24oz bottle with RO water? and how many ml a day would I need to dose?
It has construction on back for adding to ATO based off of tank vovolume and how many mg/l I want to raise it, but it also mentions not to raise Mag more ththan25g/80 L per day?
So I'm just lost and if O can add to ATO would it be 1 1/4cup added to my ATO?
TThank you for the help!

 

[Randy Holmes-Farley]

let's back up a bit. magnesium does not just happen to get that low. With the issues of testing problems and salinity, I'd want to understand how (and if) that may have happened before boosting it. That's a main reason i do not recommend testing it at all, but rather just dosing it in proportion of calcium dosing.

 

[FreshSaltyGuy]

let's back up a bit. magnesium does not just happen to get that low. With the issues of testing problems and salinity, I'd want to understand how (and if) that may have happened before boosting it. That's a main reason i do not recommend testing it at all, but rather just dosing it in proportion of calcium dosing.

My current salt level is at 1.024 at 77 degrees. I'm still new here lol. So please take what I say with a grain of salt. But I do have many years taking care of freshwater tanks a whole other beast. My Mag 2 months ago was at 1260 and has been dropping somewhat rapidly. My nitrates and phosphates are high (above 30) and I am working to bring them under control.
What should I do besides bring down my nitrates and phosphates?

 

[Randy Holmes-Farley]

My current salt level is at 1.024 at 77 degrees. I'm still new here lol. So please take what I say with a grain of salt. But I do have many years taking care of freshwater tanks a whole other beast. My Mag 2 months ago was at 1260 and has been dropping somewhat rapidly. My nitrates and phosphates are high (above 30) and I am working to bring them under control.
What should I do besides bring down my nitrates and phosphates?

Magnesium does not ever drop rapidly. The max depletion rate is about 1/10th of the calcium depletion rate.

If your specific gravity is accurate, that may be part of the issue. If you raise salinity to 35 ppt (the ocean average) them magnesium will climb from 1120 ppm to about 1185 ppm.

Try your kit on some new salt water.

 

[FreshSaltyGuy]

Magnesium does not ever drop rapidly. The max depletion rate is about 1/10th of the calcium depletion rate.

If your specific gravity is accurate, that may be part of the issue. If you raise salinity to 35 ppt (the ocean average) them magnesium will climb from 1120 ppm to about 1185 ppm.

Try your kit on some new salt water.

Ok working on raising it now. What is an acceptable level of Magnesium? I've read (may e from your posts) That Mg should be at least 1300 so that Calcium does not precipitate "fall out" is this true?

Thanks!

 

[Randy Holmes-Farley]

Ok working on raising it now. What is an acceptable level of Magnesium? I've read (may e from your posts) That Mg should be at least 1300 so that Calcium does not precipitate "fall out" is this true?

Thanks!

I recommend 1300 ppm as a target, which is a tad above the ocean average of 1280 ppm. Higher to 1400 ppm is likely fine.

It is true that magnesium helps reduce abiotic precipitation of calcium carbonate, though I think it is overplayed in importance many times. Other compounds have similar effects are rarely get similar airplay. Phosphate, organics, etc. High pH is a massive driver of precipitation, as is high alk.

 

[FreshSaltyGuy]

Ok working on raising it now. What is an acceptable level of Magnesium? I've read (may e from your posts) That Mg should be at least 1300 so that Calcium does not precipitate "fall out" is this true?

Thanks!

Oh great to know I didn't realize PH & Alk also play that role. What should I am for on PH & Alk?

 

[Randy Holmes-Farley]

Oh great to know I didn't realize PH & Alk also play that role. What should I am for on PH & Alk?

Depends on your goals. Many hard corals will grow faster at higher alk and higher pH.

Optimal Parameters for a Coral Reef Aquarium: By Randy Holmes-Farley

[note: edited on 5/29/2022 to update the nitrate and phosphate sections with higher recommended levels.] One of the main roles of an aquarist with a coral reef aquarium is to ensure that the conditions are right for their tank inhabitants. There...

www.reef2reef.com

Calcium

Many corals use calcium to form their skeletons, which are composed primarily of calcium carbonate. The corals get most of the calcium for this process from the surrounding water. Consequently, calcium often becomes depleted in aquaria housing rapidly growing corals, calcareous red algae (coralline algae), Tridacnids (clams) and Halimeda (a macroalgae containing calcium carbonate). As the calcium level drops below 360 ppm, it becomes progressively more difficult for these organisms to collect enough calcium, thus stunting their growth.

Maintaining the calcium level is one of the most important aspects of coral reef aquarium husbandry. Most reef aquarists try to maintain approximately natural levels of calcium in their aquaria (~420 ppm). It does not appear that boosting the calcium concentration above natural levels enhances calcification (i.e., skeletal growth) in most corals.

For these reasons, I suggest that aquarists maintain a calcium level between about 380 and 450 ppm, although higher is generally not a problem until it gets so high that calcium carbonate precipitation becomes problematic. Aquarists with a very light demand may be able to maintain calcium with water changes, especially since some salt mixes have excessive calcium in them. But most established aquaria with growing hard corals and coralline algae will require some calcium supplementation, and in some cases, it might be needed every day.

I usually suggest using a balanced calcium and alkalinity additive system for routine maintenance. The most popular of these balanced methods include limewater (kalkwasser), calcium carbonate/carbon dioxide reactors, and the two-part or three-part additive systems for calcium and alkalinity. If calcium is depleted and needs to be raised significantly, however, such balanced methods are not a good choice since they will raise alkalinity too much. In that case, adding calcium chloride is a good method for raising calcium in a one-time correction.

Alkalinity

Like calcium, many corals also use "alkalinity" to form their skeletons, which are composed primarily of calcium carbonate. It is generally believed that corals take up bicarbonate, convert it into carbonate, and then use that carbonate to form calcium carbonate skeletons. That conversion process is shown as:

HCO3- → CO3-- + H+

Bicarbonate → Carbonate + proton (which is released from the coral)

To ensure that corals have an adequate supply of bicarbonate for calcification, aquarists could just measure bicarbonate directly. Designing a test kit for bicarbonate, however, is somewhat more complicated than for alkalinity. Consequently, the use of alkalinity as a surrogate measure for bicarbonate is deeply entrenched in the reef aquarium hobby.

So, what is alkalinity? Alkalinity in a marine aquarium is simply a measure of the amount of acid (H+) required to reduce the pH to about 4.5, where all bicarbonate is converted into carbonic acid as follows:

HCO3- + H+ → H2CO3

The amount of acid needed is equal to the amount of bicarbonate present, so when performing an alkalinity titration with a test kit, you are “counting†the number of bicarbonate ions present. It is not, however, quite that simple since some other ions also take up acid during the titration. Both borate and carbonate also contribute to the measurement of alkalinity, but the bicarbonate dominates these other ions since they are generally lower in concentration than bicarbonate. So knowing the total alkalinity is akin to, but not exactly the same as, knowing how much bicarbonate is available to corals. In any case, total alkalinity is the standard that aquarists use for this purpose.

Unlike the calcium concentration, it is widely believed that certain organisms calcify more quickly at alkalinity levels higher than those in normal seawater. This result has also been demonstrated in the scientific literature, which has shown that adding bicarbonate to seawater increases the rate of calcification in some corals. Uptake of bicarbonate can consequently become rate limiting in many corals. This may be partly due to the fact that the external bicarbonate concentration is not large to begin with (relative to, for example, the calcium concentration, which is effectively about 5 times higher).

For these reasons, alkalinity maintenance is a critical aspect of coral reef aquarium husbandry. In the absence of supplementation, alkalinity will rapidly drop as corals use up much of what is present in seawater. Water changes are not usually sufficient to maintain alkalinity unless there is very little calcification taking place. Most reef aquarists try to maintain alkalinity at levels at or slightly above those of normal seawater, although exactly what levels different aquarists target depends a bit on the goals of their aquaria.

Interestingly, because some corals may calcify faster at higher alkalinity levels, and because the abiotic (nonbiological) precipitation of calcium carbonate on heaters and pumps also rises as alkalinity rises, the demand for alkalinity (and calcium) rises as the alkalinity rises. So an aquarist generally must dose more calcium and alkalinity EVERY DAY to maintain a higher alkalinity (say, 11 dKH) than to maintain 7 dKH. It is not just a one-time boost that is needed to make up that difference. In fact, calcification gets so slow as the alkalinity drops below 6 dKH that reef aquaria rarely get much below that point, even with no dosing: natural calcification has nearly stopped at that level.

In general, I suggest that aquarists maintain alkalinity between about 7-11 dKH (2.5 and 4 meq/L; 125-200 ppm CaCO3 equivalents). Many aquarists growing SPS corals and using Ultra Low Nutrient Systems (ULNS) have found that the corals suffer from “burnt tips†if the alkalinity is too high or changes too much. It is not at all clear why this is the case, but such aquaria are better served by alkalinity in the 7-8 dKH range.
As mentioned above, alkalinity levels above those in natural seawater increase the abiotic precipitation of calcium carbonate on warm objects such as heaters and pump impellers, or sometimes even in sand beds. This precipitation not only wastes calcium and alkalinity that aquarists are carefully adding, but it also increases equipment maintenance requirements and can “damage†a sand bed, hardening it into a chunk of limestone. When elevated alkalinity is driving this precipitation, it can also depress the calcium level. An excessively high alkalinity level can therefore create undesirable consequences.

I suggest that aquarists use a balanced calcium and alkalinity additive system of some sort for routine maintenance. The most popular of these balanced methods include limewater (kalkwasser), calcium carbonate/carbon dioxide reactors, and the two-part/three part additive systems.

For rapid alkalinity corrections, aquarists can simply use baking soda (sodium bicarbonate) or washing soda (sodium carbonate; baked baking soda) to good effect. The latter raises pH as well as alkalinity while the former has a very small pH lowering effect. Mixtures can also be used, and are what many hobby chemical supply companies sell as “buffersâ€. Most often, sodium carbonate is preferred, however, since most tanks can be helped by a pH boost.

 

[FreshSaltyGuy]

Depends on your goals. Many hard corals will grow faster at higher alk and higher pH.

Optimal Parameters for a Coral Reef Aquarium: By Randy Holmes-Farley

[note: edited on 5/29/2022 to update the nitrate and phosphate sections with higher recommended levels.] One of the main roles of an aquarist with a coral reef aquarium is to ensure that the conditions are right for their tank inhabitants. There...

www.reef2reef.com

Calcium

Many corals use calcium to form their skeletons, which are composed primarily of calcium carbonate. The corals get most of the calcium for this process from the surrounding water. Consequently, calcium often becomes depleted in aquaria housing rapidly growing corals, calcareous red algae (coralline algae), Tridacnids (clams) and Halimeda (a macroalgae containing calcium carbonate). As the calcium level drops below 360 ppm, it becomes progressively more difficult for these organisms to collect enough calcium, thus stunting their growth.

Maintaining the calcium level is one of the most important aspects of coral reef aquarium husbandry. Most reef aquarists try to maintain approximately natural levels of calcium in their aquaria (~420 ppm). It does not appear that boosting the calcium concentration above natural levels enhances calcification (i.e., skeletal growth) in most corals.

For these reasons, I suggest that aquarists maintain a calcium level between about 380 and 450 ppm, although higher is generally not a problem until it gets so high that calcium carbonate precipitation becomes problematic. Aquarists with a very light demand may be able to maintain calcium with water changes, especially since some salt mixes have excessive calcium in them. But most established aquaria with growing hard corals and coralline algae will require some calcium supplementation, and in some cases, it might be needed every day.

I usually suggest using a balanced calcium and alkalinity additive system for routine maintenance. The most popular of these balanced methods include limewater (kalkwasser), calcium carbonate/carbon dioxide reactors, and the two-part or three-part additive systems for calcium and alkalinity. If calcium is depleted and needs to be raised significantly, however, such balanced methods are not a good choice since they will raise alkalinity too much. In that case, adding calcium chloride is a good method for raising calcium in a one-time correction.

Alkalinity

Like calcium, many corals also use "alkalinity" to form their skeletons, which are composed primarily of calcium carbonate. It is generally believed that corals take up bicarbonate, convert it into carbonate, and then use that carbonate to form calcium carbonate skeletons. That conversion process is shown as:

HCO3- → CO3-- + H+

Bicarbonate → Carbonate + proton (which is released from the coral)

To ensure that corals have an adequate supply of bicarbonate for calcification, aquarists could just measure bicarbonate directly. Designing a test kit for bicarbonate, however, is somewhat more complicated than for alkalinity. Consequently, the use of alkalinity as a surrogate measure for bicarbonate is deeply entrenched in the reef aquarium hobby.

So, what is alkalinity? Alkalinity in a marine aquarium is simply a measure of the amount of acid (H+) required to reduce the pH to about 4.5, where all bicarbonate is converted into carbonic acid as follows:

HCO3- + H+ → H2CO3

The amount of acid needed is equal to the amount of bicarbonate present, so when performing an alkalinity titration with a test kit, you are “counting†the number of bicarbonate ions present. It is not, however, quite that simple since some other ions also take up acid during the titration. Both borate and carbonate also contribute to the measurement of alkalinity, but the bicarbonate dominates these other ions since they are generally lower in concentration than bicarbonate. So knowing the total alkalinity is akin to, but not exactly the same as, knowing how much bicarbonate is available to corals. In any case, total alkalinity is the standard that aquarists use for this purpose.

Unlike the calcium concentration, it is widely believed that certain organisms calcify more quickly at alkalinity levels higher than those in normal seawater. This result has also been demonstrated in the scientific literature, which has shown that adding bicarbonate to seawater increases the rate of calcification in some corals. Uptake of bicarbonate can consequently become rate limiting in many corals. This may be partly due to the fact that the external bicarbonate concentration is not large to begin with (relative to, for example, the calcium concentration, which is effectively about 5 times higher).

For these reasons, alkalinity maintenance is a critical aspect of coral reef aquarium husbandry. In the absence of supplementation, alkalinity will rapidly drop as corals use up much of what is present in seawater. Water changes are not usually sufficient to maintain alkalinity unless there is very little calcification taking place. Most reef aquarists try to maintain alkalinity at levels at or slightly above those of normal seawater, although exactly what levels different aquarists target depends a bit on the goals of their aquaria.

Interestingly, because some corals may calcify faster at higher alkalinity levels, and because the abiotic (nonbiological) precipitation of calcium carbonate on heaters and pumps also rises as alkalinity rises, the demand for alkalinity (and calcium) rises as the alkalinity rises. So an aquarist generally must dose more calcium and alkalinity EVERY DAY to maintain a higher alkalinity (say, 11 dKH) than to maintain 7 dKH. It is not just a one-time boost that is needed to make up that difference. In fact, calcification gets so slow as the alkalinity drops below 6 dKH that reef aquaria rarely get much below that point, even with no dosing: natural calcification has nearly stopped at that level.

In general, I suggest that aquarists maintain alkalinity between about 7-11 dKH (2.5 and 4 meq/L; 125-200 ppm CaCO3 equivalents). Many aquarists growing SPS corals and using Ultra Low Nutrient Systems (ULNS) have found that the corals suffer from “burnt tips†if the alkalinity is too high or changes too much. It is not at all clear why this is the case, but such aquaria are better served by alkalinity in the 7-8 dKH range.
As mentioned above, alkalinity levels above those in natural seawater increase the abiotic precipitation of calcium carbonate on warm objects such as heaters and pump impellers, or sometimes even in sand beds. This precipitation not only wastes calcium and alkalinity that aquarists are carefully adding, but it also increases equipment maintenance requirements and can “damage†a sand bed, hardening it into a chunk of limestone. When elevated alkalinity is driving this precipitation, it can also depress the calcium level. An excessively high alkalinity level can therefore create undesirable consequences.

I suggest that aquarists use a balanced calcium and alkalinity additive system of some sort for routine maintenance. The most popular of these balanced methods include limewater (kalkwasser), calcium carbonate/carbon dioxide reactors, and the two-part/three part additive systems.

For rapid alkalinity corrections, aquarists can simply use baking soda (sodium bicarbonate) or washing soda (sodium carbonate; baked baking soda) to good effect. The latter raises pH as well as alkalinity while the former has a very small pH lowering effect. Mixtures can also be used, and are what many hobby chemical supply companies sell as “buffersâ€. Most often, sodium carbonate is preferred, however, since most tanks can be helped by a pH boost.

Excellent writeup appreciate this and you.

 

[Randy Holmes-Farley]

Excellent writeup appreciate this and you.

Thank you.

Happy Reefing.