Dosing Mg without raising pH, KH, or GH?

[reef_research]

Is it possible to dose magnesium in a freshwater or brackish tank without seriously affecting the pH, KH, or GH of the water?

Also, what would be the best method?


thank you,

 

[Billybeau1]

I guess I would ask first..... why do you want to dose magnesium in a fresh or brackish tank ?

 

[reef_research]

I am interested in seeing how I can prolong the life and wellbeing of redmangroves in a FW or BW system. Many folks coimplian of having them do fine for a while, then simply wither away, even with daily spraying of the leaves.

 

[Boomer]

What kind of Mg++ ? MgCl will have no effect on those except GH, as GH is 99 % Ca++ and Mg++.

How are they withering away excactly ? Maybe it is the lack of iron they are not getting. Many plants suffer or can suffer from chlorosis.

 

[reef_research]

which would be the most common culprit?

Also, since the range of BW plants is not very much, and many articles mention not adding iron unless you have a lot of macros, what would be the best way to figure out what you need to suppliment for the tanks benefit as well as the mangroves survival?

 

[Boomer]

I would try to keep the them at the same level as the BW. Here is something on iron.

Iron

First Iron Article: Macroalgae and Dosing Recommendations
http://www.advancedaquarist.com/issues/aug2002/chem.htm

Second Iron Article: Iron: A Look at Organisms Other than Macroalgae
http://www.advancedaquarist.com/issues/oct2002/chem.htm

 

[Boomer]

I do some checking on mangroves tomorrow for you

 

[Boomer]

Well, I see the reason by your asking about Mg++ although you did not say why. Red mangroves need a proper supply of Mg++ or they just turn yellow, wither away and may die. Srapying helps many plants get the mositure they need, do to it does not rain in your living room nor is it as humid The spraying also washes the leaves of salt deposites. Lighitng is another issue and they prefer bulbs in the 6000°-8000°K range.

We can figure how much is needed by knowing the salinity of the BW and go from there. These plants, in a salt environment, pull in to much Sodium from the water and need to pump it out. It is a cellular process where these plants pump in Mg++ to remove the excessive Na+ from the cells. Failure to reduce this Na+ salt form its system causes "salt stress" on the Mangroves which will not allow it to survive very long. So in short, this is a form of chlorosis, meaning almost any yellowing of the leaves and withering, caused by the lack of a nutrient. Red Mangroves can deplete Mg++ quickly in something like BW and especially FW, so it needs to be monitored weekly.

As far as what additve for Mg++ is best it is hard to say. There are two basic choices, Magnesium chloride or Magnesium sulfate. Niether add to the GH but both still add to the salinity. IMHO the sulfate would be a better choice, as many plants don't' like chlorides.

As I had mentoined earlier, although I was not sure, Iron is an import sup for Red Mangroves. Matter of fact, there is a foundation, the Red Ball Foundation, that specializes in transplanting Red Mangroves and has developed a special pot filled with their potting soil, which is sup'd with a slowly releasing Iron sup.

Red Ball Foundation
http://www.reefball.org/album/cayma...sproject/redmangrovenurseryproject/index.html

Something to learn about Mg++

Magnesium in Reef Aquaria
http://www.advancedaquarist.com/issues/oct2003/chem.htm

 

[reef_research]

Ok, iron seems to be fairly well covered in the FW realm, and in SW applications, there is enough information for whats needed.

Magnesium (sulfate, for FW, and/or chloride for BW?) looks like the main problem here.

What are the ways of testing for Mg (and its compounds) in FW, BW, and SW aquaria?

Are the tests reliant on specific gravity, ie; only work in marine environments?

If these commonly availible test only work in SW, how can one measure Mg in FW or BW?

What is the tolerance to Mg in FW/BW organisms, including inverts?

Thank you,

 

[Boomer]

Magnesium (sulfate, for FW, and/or chloride for BW?) looks like the main problem here.

********Sulfate is more common in FW but Chloride is more common in BW or SW. In seawater it is Cl- is19,000 ppm and sulfate is 2,700 ppm. You could make up a sup using both. Red Mangroves to fine in SW.

What are the ways of testing for Mg (and its compounds) in FW, BW, and SW aquaria?

*********You will never be able to test for sulfate with any kind of kit in BW or SW. A sulfate kit for FEW will cost you a arm & leg You can buy chloride test kits from HACH, but a good floating 12" SG hydrometer will be fine, like a Tropic Marin or a refract calibrated to RO/DI will be fine also to determine salinity in BW. Any reef type Mg++ like a will be fine. How much do you want to spend ?

Are the tests reliant on specific gravity, ie; only work in marine environments?

********They will work fine in either environment

If these commonly availible test only work in SW, how can one measure Mg in FW or BW?

********They are the pretty much the same

What is the tolerance to Mg in FW/BW organisms, including inverts?

********Very high tolerance, Mg++ in seawater is 1300 ppm. Red Mangroves can do fine in SW even if the Mg++ is at 3/4 strength.

What are you calling BW. Which do you want to run BW or FW or both.

 

[reef_research]

I'm looking at two scenarios, one full freshwater, and one brackish (though loosely defined by hobbiest usages)

What is used to test for MG in SW tanks?

With tolerance, how do freshwater organism do?

thanks,

 

[Boomer]

What is used to test for MG in SW tanks?

****A Mg++ test kit like a Salifert

With tolerance, how do freshwater organism do?

***Mg++ is not toxic. And you are not going to be runing it in the hundreds of ppm in FW. The less salt, thus the less Na++, the less Mg++ is needed. In FW it is really not needed as there is little or no Na++, therefore little or no Mg++ is required.

brackish

Well, again what are you calling BW ? It has a wide range 0.5 - 30 ‰. So where are you planning to be, which will be function of how much Mg++ you will need. Each 1 ‰ should have about 30-40 ppm Mg++.

 

[reef_research]

"It has a wide range 0.5 - 30 ‰. So where are you planning to be, which will be function of how much Mg++ you will need. Each 1 ‰ should have about 30-40 ppm Mg++."

I'm afraid i don't understand what you're saying. Percentage of what?

Also, to be clear, what you're saying in the first part is that red mangroves will not need any Mg if kept in FW?

Thanks,

 

[Boomer]

I'm afraid i don't understand what you're saying. Percentage of what?

That is not % but ‰, which is parts / thousand or ppt and seawater is 35 ppt, which is 35 ‰ and BW runs from 0.05 - 30 ‰ or ppt.

What I said they do not need Mg in FW. The Mg++ is only used to pump out Na+, Sodium and since there is almost none in FW then Mg ++ is not needed. Mg++ is not a limiting nutrient in FW for Mangroves. The high Na+ in BW and especially seawater is what casues problems for Mangroves, which is not an issue in FW.

 

[Billybeau1]

If I remember correctly, brackish water runs about 1.017 to 1.019 sg.

If that helps.

 

[reef_research]

Since most seem to be using SG in brackish tanks, what is the formula (is there one?) for finding out how many ppm of Mg that you need?

ie; salinity of X=Yppm of Mg


Thanks,

 

[Boomer]

I see I made a typo that .05 is suppose to be 0.5. and 0.5 ‰ is an SG of 1.00038 or 500 ppm.

NSW @ 35,000 ppm. The Caspian Sea @ 12,000 ppm and Baltic Seas, a wide range depending on location @ 1,000 -20,000 are examples of BW. Lagoons, marshes, deltas and estuaries are also BW. St. Charles Lake in Louisiana is around 3 ‰ or 3,000 ppm

Water by definition of saline content in ‰ as seawater salinity.

Fresh water......Brackish water.....Saline water....... Brine
< 0.5 ‰..............0.5 - 30 ‰........30 - 50 ‰......> 50 ‰



Although IMHO 500 ppm is getting way to carrier away, meaning many tap water supplies are 500 ppm. It should be more like 1,000 ppm or even 2,000. Fresh water marshes are defined as not exceeding 2,000 ppm or 2 ‰

 

[Boomer]

ie; salinity of X=Yppm of Mg

I already told you that.

Each 1 ‰ should have about 30-40 ppm Mg++."

How about if I make it easier. Go to the SG far left and look up what you have and go across until you hit the 25 C column and look for the Salinity.

Example for BW

1.020 @ 25 C= 26.56 ‰ Salinity

Each 1 ‰ should have about 30-40 ppm Mg++."

If we take 37 ppm Mg++, then 26.56 x 37 = 983 ppm Mg++ @ 1.020 SG

 

[reef_research]

I don't think the chart goes low enough for brackish...

Basically, all i need is the specific gravity converted to PPT, and then multiply by 30-40?

Thanks,

 

[Boomer]

I forgot about that table not going low enough and forgot I had this.

And yes PPT x 30-40


http://www.americanmarineusa.com/salinityconversion.html