# Calcium Magnesium questions



## consettbay2003 (Mar 11, 2007)

As I am unable to locate a source for MSU fertilizer in the U.K. I would like some information on supplementing my regular fertilizer with these two elements. From what I have read it seems to be the concensus not to mix calcium nitrate and magnesium sulfate together as this will cause a precipitation of calcium sulfate to occur. I have mixed 1/2 tsp calcium nitrate and 1/2 tsp magnesium sulfate in one gallon of RO water and see no evidence of a precipitate forming. 

Comments are welcomed.


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## likespaphs (Mar 11, 2007)

i can't remember what it is but there is a ratio at which calcium and magnesium should be used as they can be antagonistic.
you could look around for a fertilizer at a plant seller which would be labeled 'cal-mag' or something similar...


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## gonewild (Mar 11, 2007)

You won't see precipitates until you mix stronger concentrations. At concentrations that you would apply directly to your plants you won't have a problem. If you try to mix a concentrated solution to use with a fertilizer injector then you may have the problem.


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## consettbay2003 (Mar 11, 2007)

I checked the Antec website and they seem to think 30-50 ppm calcium and 20-30 ppm magnesium is adequate for paphs., so it looks like a ration of 2 calcium nitrate: 1 magnesium sulfate would be acceptable.


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## gonewild (Mar 11, 2007)

You can make your own MSU fertilizer, just follow the recipe on the label to get thge ratio of nutrients correct:

Total Nitrogen……………………………….….13%
12.5% Nitrate Nitrogen
0.7% Ammoniacal Nitrogen
Available Phosphate (P2O3)…………………..….3%
Potash (K2O)……………………………………15%
Calcium…………………………………..…….8.0%
Magnesium………………………………..……2.0%
Iron (Fe)……………………………………...0.177%
Manganese (Mn)…………………………..…0.088%
Zinc (Zn)…………………………………..…0.041%
Copper (Cu)……………………………….…0.044%
Boron (B)………………………………….…0.018%
Molybdenum (Mo)…………………………..0.018%


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## consettbay2003 (Mar 11, 2007)

excuse me Remind me to send you a batch of my home made cookies, so you can see how good I am with a recipe! I was one of the nerds in the back row of the chemistry class.


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## gonewild (Mar 11, 2007)

consettbay2003 said:


> excuse me Remind me to send you a batch of my home made cookies, so you can see how good I am with a recipe! I was one of the nerds in the back row of the chemistry class.



:rollhappy: 

I thought nerds were the ones who did well in class?
How is your math?

On the MSU fertilizer analysis you can see the calcium to magnesium ratio is 4:1. Bob at Antec stated that he feels it should be higher in magnesium for paphs and phrags.

Don't forget when you calculate how much to add to your fertilizer you need to base it on the % of the nutrient and not the volume. 4:1 does not mean 4 spoons of Calcium nitrate with one spoon of Magnesium sulfate.


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## IdahoOrchid (Mar 11, 2007)

Is calcium nitrate a source of calcium, nitrogen or both?


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## consettbay2003 (Mar 11, 2007)

It's a source of both calcium and nitrogen (nitrate form)

I am planning on using 1 tsp Calcium Nitrate to 1/4 teaspoon Magnesium Sulphate as an feeding in between regular fertilizing. My regular fertilizer contains 2% MgSO4 but no calcium.


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## Hien (Mar 11, 2007)

I am kind of lazy to do too much mixing & measuring, Can I just use the dolomite lime from garden center?
(since they list both calcium and magnesium as components of the dolomite lime)


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## Rick (Mar 13, 2007)

gonewild said:


> You won't see precipitates until you mix stronger concentrations. At concentrations that you would apply directly to your plants you won't have a problem. If you try to mix a concentrated solution to use with a fertilizer injector then you may have the problem.



The formation of calcium sulfate is also driven by high pH, and since you'll be staying under 9 s.u. with this mix you will need to get pretty high concentrations to cause the gypsum to form.


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## NYEric (Mar 16, 2007)




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## Bob Wellenstein (Mar 16, 2007)

You need not be concerned, Eric, about the pH and precipitation unless you are mixing concentrates for injectors. At that concentration the mixture stays in solution because it is quite acidic. You cannot alter the pH or you will form precipitates, so we use a second injector with a potassium bicarbonate solution to inject behind the fertilizer. Again, only a concern for those mixing very concentrated solutions.


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## NYEric (Mar 16, 2007)

I'm just hoping everything I need is in the fertilizer and MSU formulas.


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## charlie c (Mar 16, 2007)

Lynn/Bob,

In your experience, is there any benefit/detriment to feeding Epsom Salts on a regular low dose regimen (say, 1/4 teaspoon per gal every watering) as opposed to the large bolus every month or two?

charlie c


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## gonewild (Mar 16, 2007)

NYEric said:


> I'm just hoping everything I need is in the fertilizer and MSU formulas.



Bob made a point that fertilizers don't have enough magnesium content for slippers. He recommended applying additional every few months. There seems to be no published exact ratio between calcium and magnesium that is proven to be best. But Bob certainly knows from his experience that paphs and phrags like more magnesium than supplied by the MSU formulas. I'm going to add additional magnesium to my fertilizer solution to see what happens.


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## NYEric (Mar 16, 2007)

So should I buy a bottle of milk of magnesia also..?


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## IdahoOrchid (Mar 16, 2007)

NYEric said:


> So should I buy a bottle of milk of magnesia also..?


Only if this discussion is making you ill!:crazy:


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## Rick (Mar 16, 2007)

gonewild said:


> Bob made a point that fertilizers don't have enough magnesium content for slippers. He recommended applying additional every few months. There seems to be no published exact ratio between calcium and magnesium that is proven to be best. But Bob certainly knows from his experience that paphs and phrags like more magnesium than supplied by the MSU formulas. I'm going to add additional magnesium to my fertilizer solution to see what happens.



I spike my low pH (6-6.5) with a dash of magnesium sulfate. For my higher pH plants (7-8) I use a dash of magnesium hydroxide.


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## NYEric (Mar 17, 2007)

Umm, when I go downstairs to the supermarket do I ask the manager " Where do you keep your magnesium sulfate and magnesium hydroxide?"!?


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## Heather (Mar 17, 2007)

Yes!


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## NYEric (Mar 17, 2007)

Doh!


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## gonewild (Mar 17, 2007)

I think adding 1/2 teaspoon of Epson Salts per 3 teaspoons of MSU fertilizer used will add an additional 2% Magnesium to the fertilizer balance. 

Anybody care to check my calculations?


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## NYEric (Mar 17, 2007)

Since I'm using MSU aat 1/2 teaspoon / Gallon of water I'll have to pre-mix some. At least my feet will get a good soak in epsom salts.


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## gonewild (Mar 17, 2007)

NYEric said:


> Since I'm using MSU aat 1/2 teaspoon / Gallon of water I'll have to pre-mix some. At least my feet will get a good soak in epsom salts.




Mix it dry. Mix 2 tablespoons of MSU and 1 teaspoon of Epsom Salt.
(Note the difference tablespoon and teaspoon)
Mix the dry salts together then measure out your 1/2 teaspoon to mix per gallon of water.

The result will only slightly lower the other nutrients in the total final solution.


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## NYEric (Mar 17, 2007)

Thanx. Maybe that will induce the Paphs to bloom instead of divide.


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## gonewild (Mar 18, 2007)

NYEric said:


> Thanx. Maybe that will induce the Paphs to bloom instead of divide.



Or divide twice as fast?


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## consettbay2003 (Mar 18, 2007)

Gonewild

I do not have access to MSU fertilizer. The one I am currently using has 2% Magnesium Sulfate but 0% calcium. I use RO water.
How much calcium nitrate would you suggest I add to your dry formula mix ( 2 TBS Fertilizer, plus 1 tsp MgS04 ) to get a reasonable balance of Mg/Ca?

I use a constant feed at 1/4 tsp/gal.


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## IdahoOrchid (Mar 18, 2007)

NYEric said:


> Thanx. Maybe that will induce the Paphs to bloom instead of divide.



It is my understanding that Magnesium helps/improves the photosynthesis process rather than the blooming one.

Lance?


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## TADD (Mar 18, 2007)

I agree with Steven, It always greens up the plants real well!


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## gonewild (Mar 18, 2007)

consettbay2003 said:


> Gonewild
> 
> I do not have access to MSU fertilizer. The one I am currently using has 2% Magnesium Sulfate but 0% calcium. I use RO water.
> How much calcium nitrate would you suggest I add to your dry formula mix ( 2 TBS Fertilizer, plus 1 tsp MgS04 ) to get a reasonable balance of Mg/Ca?
> ...



That will depend on what else is in the fertilizer you are using. Calcium nitrate will also add some nitrogen so that needs to be considered for the total. Tell me the % of nutrients in the fertilizer you are using and I'll see how it works out.


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## gonewild (Mar 18, 2007)

IdahoOrchid said:


> It is my understanding that Magnesium helps/improves the photosynthesis process rather than the blooming one.
> 
> Lance?



That is correct magnesium is an important nutrient for the leaf chlorophyll function. But the first step in getting plants to bloom faster and better is to grow them faster and better.

I don't think any nutrient has really been proven to initiate blooming. Deficiencies may prevent or delay blooming but adding extra won't directly cause blooming.


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## L I Jane (Mar 18, 2007)

Does anyone know if the Epsom salts treatment is just used for paphs or all of our orchids?


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## gonewild (Mar 18, 2007)

L I Jane said:


> Does anyone know if the Epsom salts treatment is just used for paphs or all of our orchids?



You can use Epsom salts on other orchids too.

Epsom salts is just another name for Magnesium sulfate which is a common ingredient in fertilizer mixes. All plants need magnesium along with other nutrients.


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## consettbay2003 (Mar 18, 2007)

Gonewild,
The fertilizer I use is from Ratcliffe Orchids and the formula is 26-6-11, 15.50% of the nitrogen is from nitrate nitrogen ( balance ammoniacal ).

They also offer a 15-7-30 formula ( 11.50% Nitrate, balance ammoniacal ), but I was concerned about the level of K.

As I mentioned previously I use a constant feed of 1/4 tsp/gallon.


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## L I Jane (Mar 18, 2007)

Thanks Lance!


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## gonewild (Mar 18, 2007)

consettbay2003 said:


> Gonewild,
> The fertilizer I use is from Ratcliffe Orchids and the formula is 26-6-11, 15.50% of the nitrogen is from nitrate nitrogen ( balance ammoniacal ).
> 
> They also offer a 15-7-30 formula ( 11.50% Nitrate, balance ammoniacal ), but I was concerned about the level of K.
> ...



OK. 

Does it say on the package what chemicals (ingredients) are used in the formula? (Sometimes fertilizers may contain calcium but not list it on the label.)

I think adding the Calcium Nitrate to the 15-7-30 formula will be better because the extra nitrogen from the Calcium nitrate will raise the nitrogen level and thus effectively lower the potassium level.

After lunch I'll figure out how much Calcium nitrate I would add.


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## consettbay2003 (Mar 18, 2007)

Gonewild,
I do not see calcium as part of any of the ingredients on the label. There is 2% magnesium sulphate.

Thanks for your help.


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## gonewild (Mar 18, 2007)

consettbay2003 said:


> Gonewild,
> I do not see calcium as part of any of the ingredients on the label. There is 2% magnesium sulphate.
> 
> Thanks for your help.



OK.

Are there any other micro nutrients listed?

Now I'm going for lunch :clap:


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## gonewild (Mar 18, 2007)

consettbay2003 said:


> Gonewild,
> I do not see calcium as part of any of the ingredients on the label. There is 2% magnesium sulphate.
> 
> Thanks for your help.



Is that 2% magnesium?
or 
2% magnesium sulfate?


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## consettbay2003 (Mar 18, 2007)

Gonewild,
It actually 2% magnesium oxide. I mistakenly assumed it was magnesium sulphate.

Macronutrients:
Nitrogen 26%
Nitrate nitrogen (NO3-N) 15.5%
Ammoniacal nitrogen 10.5%

Phosphorus Pentoxide Soluble (P2O5) 6%

Potassium Oxide Soluble (K2O) 11%


Micronutrients:
Magnesium oxide 2%
Boron (B) 300mg/kg
Copper (Cu) 200mg/kg
Chelated Iron 1533mg/kg
Manganese (Mn) 1000mg/kg
Molybdenum (Mo) 120mg/kg
Zinc (Zn) 270mg/kg

It seems I am low in magnesium, and lacking sulphur and calcium.


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## gonewild (Mar 18, 2007)

Consettbay,
Here is a recipe to make a ratio similar to the MSU formula I use. The percentages are all rounded off and are approximate values.

Start with the 15-7-30 fertilizer formula as the base. I am assuming it has 2%magnesium content, if not we need to slightly readjust this recipe.

Mix these amounts together in the dry salt form. (Mix very well, make sure all lumps are crushed). Measure accurately.

10 parts 15-7-30 fertilizer.
7 parts Calcium nitrate.
3 parts Magnesium sulfate (Epsom salt).

Once mixed this gives you a fertilizer of (13-3.5-15-6.7-2.4)
13% Nitrogen
3.5% Phosphorous
15% Potassium
6.7% Calcium
2.4% Magnesium

If you mix 1/2 tsp/gallon of this new formula you will have about the same nitrogen level you are applying now (86 ppm), but you will have more potassium, calcium and magnesium which will raise your total ppm about 80 ppm, not a problem.

To get the calcium % higher we would need to raise the nitrogen level higher than the potassium which would not be similar to the MSU formula. To raise the calcium and keep the NPK ratio I think we would need to use some Potassium nitrate also. But I think the 6.7% calcium is enough and it is a 3:1 ratio with magnesium which is a little higher than the MSU.

*You should also add a micro nutrient mix to give all the nutrients the MSU formula has and plants need.*

Your current fertilizer has a lot higher nitrogen ratio with NPK _26-6-11_.
If you want to keep using the high nitrogen balance which is not similar to the MSU formula you can mix equal parts of the NPK_26-6-11_ with Calcium nitrate and wind up with NPK_21-3-5.5_ with 9.5% calcium added.

Depending on what media you grow in with the high nitrogen ratio you are probably either wasting nitrogen or underfeeding potassium.

Hope this makes sense and helps.
If anybody cares to dispute my calculations I'm happy to listen.


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## consettbay2003 (Mar 18, 2007)

Thanks Gonewild, I really appreciate the time and effort you have put into helping me to get a more balanced fertilizer. I hope others have benefited from your generosity on this thread. 

Bill


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## gonewild (Mar 18, 2007)

consettbay2003 said:


> Gonewild,
> It actually 2% magnesium oxide. I mistakenly assumed it was magnesium sulphate.



Then it only has about half as much actual magnesium. That's not a problem because there is some extra in Calcium nitrate that I did not calculate in to what I suggested.  




> Micronutrients:
> Magnesium oxide 2%
> Boron (B) 300mg/kg
> Copper (Cu) 200mg/kg
> ...



With these already in the base fertilizer you won't need to add micro nutrients as I suggested.



> It seems I am low in magnesium, and lacking sulphur and calcium.



You will get about 2% sulfur in the new recipe with the addition of the Magnesium sulfate.


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## gonewild (Mar 18, 2007)

consettbay2003 said:


> Thanks Gonewild, I really appreciate the time and effort you have put into helping me to get a more balanced fertilizer. I hope others have benefited from your generosity on this thread.
> 
> Bill



Your welcome. Thanks for asking the question.
Where there is a will there is a way. :wink:


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