NPK changes from Calmag

Kingrow1

Kingrow1

Well-Known Member
My cal mag has a 3:3:1 ratio Nitrogen:Calcium:Magnesium. If i add 100ppm im adding (approx) 43ppm Nitrogen, 43ppm Calcium: 14ppm Magnesium.

If i take 500ppm of NPK 2-1-2 and add 200ppm of my calmag then instantly i have made a 2.86:1:2 or pretty close to a 3-1-2 final NPK.

Should i add 500ppm of calmag then im safely at a 4-1-2 NPK.

Working with this i would just need to throw in some trace elements and a touch of sulphur and i have a complete fertilizer roughly 4-1-2-2-0.7 NPK Ca Mg.
 
MisterBlah

MisterBlah

Well-Known Member
Alright, so, in reading a lot of your posts, you seem to misunderstand ratios with chemical concentration.

Bear with me for a second, because this will all make sense in a bit.

First off, all fertilizers in the US are sold on a weight/weight% basis. This means a fertilizer that has a 2-1-2 on the bottle is 2% total nitrogen, 1% phosphate as P2O5, and 2% potassium as K2O, by weight.

Concentrations of elements in an aqueous solution, water, are measured in weight/volume. The concentrations that read as PPM, parts per million, are equal to a measurement of mg/L. So, if I add 100 mg/L of a 2-1-2 fertilizer, I have now has a solution that is 2 ppm total nitrogen, 1 ppm phosphate as P2O5, and 2 ppm potassium as K2O.

Lets now consider your calmag blend. You say it has a 3:3:1 ratio of N:Ca:Mg. That's all well and good. But it doesn't tell us anything about the weight/weight% of the fertilizer. If it says it is 3% N, 3% Ca, and 1% Mg on the bottle, then it's useful information. In which case, adding 100mg/L, which is 100ppm, of this fertilizer will give you a solution that is 3 ppm N, 3 ppm Ca, and 1 ppm Mg.

Now, let us consider a common calcium nitrate fertilizer. It is 15.5% total N and 19% Ca. So, if I add 100 mg/L of this calcium nitrate fertilizer, I will have a feed solution that is 15.5 ppm total N and 19 ppm Ca. If I want 100 ppm of Ca, I need to add more of this fertilizer. Specifically, I need to add 526 mg/L of it. This will mean I have 81.5 ppm total N and 100 ppm Ca. Now, I want to add magnesium to this. I chose a magnesium nitrate fertilizer. It is 11% total N and 9.6% Mg. To reach my 3:1 ratio of Ca to Mg, I need 33 ppm Mg in solution. To get 33 ppm Mg, I need to add 344 ppm of this magnesium nitrate fertilizer. This means I will also be adding 37.8 ppm of N to the solution. Bringing the total N concentration to 118.3 ppm.

So, a blend of the following:
526 mg/L (2.0 g/gal) of calcium nitrate
344 mg/L (1.33g/gal) of magnesium nitrate

will create a solution with the following concentration:
118.3 ppm N
100 ppm Ca
33 ppm Mg

This is a solution with a 3.5:3:1 N:Ca:Mg ratio.

I hope this helps you along with what you're working on.
 
Kingrow1

Kingrow1

Well-Known Member
MisterBlah said:
Alright, so, in reading a lot of your posts, you seem to misunderstand ratios with chemical concentration.

Bear with me for a second, because this will all make sense in a bit.

First off, all fertilizers in the US are sold on a weight/weight% basis. This means a fertilizer that has a 2-1-2 on the bottle is 2% total nitrogen, 1% phosphate as P2O5, and 2% potassium as K2O, by weight.

Concentrations of elements in an aqueous solution, water, are measured in weight/volume. The concentrations that read as PPM, parts per million, are equal to a measurement of mg/L. So, if I add 100 mg/L of a 2-1-2 fertilizer, I have now has a solution that is 2 ppm total nitrogen, 1 ppm phosphate as P2O5, and 2 ppm potassium as K2O.

Lets now consider your calmag blend. You say it has a 3:3:1 ratio of N:Ca:Mg. That's all well and good. But it doesn't tell us anything about the weight/weight% of the fertilizer. If it says it is 3% N, 3% Ca, and 1% Mg on the bottle, then it's useful information. In which case, adding 100mg/L, which is 100ppm, of this fertilizer will give you a solution that is 3 ppm N, 3 ppm Ca, and 1 ppm Mg.

Now, let us consider a common calcium nitrate fertilizer. It is 15.5% total N and 19% Ca. So, if I add 100 mg/L of this calcium nitrate fertilizer, I will have a feed solution that is 15.5 ppm total N and 19 ppm Ca. If I want 100 ppm of Ca, I need to add more of this fertilizer. Specifically, I need to add 526 mg/L of it. This will mean I have 81.5 ppm total N and 100 ppm Ca. Now, I want to add magnesium to this. I chose a magnesium nitrate fertilizer. It is 11% total N and 9.6% Mg. To reach my 3:1 ratio of Ca to Mg, I need 33 ppm Mg in solution. To get 33 ppm Mg, I need to add 344 ppm of this magnesium nitrate fertilizer. This means I will also be adding 37.8 ppm of N to the solution. Bringing the total N concentration to 118.3 ppm.

So, a blend of the following:
526 mg/L (2.0 g/gal) of calcium nitrate
344 mg/L (1.33g/gal) of magnesium nitrate

will create a solution with the following concentration:
118.3 ppm N
100 ppm Ca
33 ppm Mg

This is a solution with a 3.5:3:1 N:Ca:Mg ratio.

I hope this helps you along with what you're working on.
Click to expand...

So 500ppm of a 2-1-2 of npk does not make 200ppm nitrogen 100ppm phosphorus 200ppm potassium?
 
B

bryan oconner

Well-Known Member
lol damn calmag . I just pore it in until that stuff looks good to me in the water guess I should measure it lol . never do on calmag . its great stuff works well to keep the calcium strong.
 
MisterBlah

MisterBlah

Well-Known Member
Kingrow1 said:
So 500ppm of a 2-1-2 of npk does not make 200ppm nitrogen 100ppm phosphorus 200ppm potassium?
Click to expand...
That is correct. 500 ppm of your 2-1-2 will give you 10 ppm N, 5 ppm P2O5, and 10 ppm K2O.

Something you probably just noticed was my use of P2O5 in place of phosphorus and K2O in place of potassium. This is important because that is what those numbers on the bottle actually stand for.

To convert to a real concentration of phosphorus from P2O5, multiple the P2O5 concentration by 0.436 and you will get your true phosphorus concentration.

To convert to a real concentration of potassium, multiple the K2O numbers by 0.83 and you will get your true potassium concentration.


Now, lets clarify what 100 ppm of a liquid fertilizer really is.

Check on the bottle and you should see a weight somewhere. If you've got 1 gallon, it will be around 9.5-13 lbs. Divide that number by 8.34, the density of pure water, to get your specific gravity, SG. Now, we need to do some math to determine how much volume we need to add that will equal 100 ppm of this liquid fertilizer.

Lets assume your fertilizer weighs 10.4 lbs. That's 10.4/8.34 = 1.247 = SG.

Alright, well, now I want to add 100 ppm of that fertilizer. How much volume is it to do that?

100 ppm means to add 100 mg/L. If it were just water, it would be easy as water has a mass of just about 1 g/ml. But it's not. So, we need to do a little extra. 100 mg of this fertilizer with an SG of 1.247. 100mg = 0.1g. It is important that we convert to grams instead of milligrams right here because we want a value in mL instead of uL. 0.1g/1.247SG = 0.080. We need to add 0.080mL/L to get 100 ppm of this liquid fertilizer, and that will give us 2 ppm N, 1 ppm P2O5, and 2 ppm K2O.

Now, if you want 200 ppm of N, you will need to add 10,000 ppm of this liquid fertilizer. 10,000 ppm of this fertilizer is 8mL/L. 8mL/L = 30.3mL/gallon.

Your final solution will then be the following
200 ppm total N
43.6 ppm P (100 ppm P2O5)
166 ppm K (200 ppm K2O)
 
B

bryan oconner

Well-Known Member
my issue is my nutrient are not that low in cal . I actually lock it out because I push the p so hard . ppm or the p are way past the suggest range plants should dye. and I over do the calmag to compensate .
 
MisterBlah

MisterBlah

Well-Known Member
bryan oconner said:
my issue is my nutrient are not that low in cal . I actually lock it out because I push the p so hard . ppm or the p are way past the suggest range plants should dye. and I over do the calmag to compensate .
Click to expand...
The number one way to cause a calcium or magnesium deficiency is to have too high potassium levels, not phosphorus. Potassium competes with other positively charged ions, like calcium and magnesium.
 
Kingrow1

Kingrow1

Well-Known Member
MisterBlah said:
That is correct. 500 ppm of your 2-1-2 will give you 10 ppm N, 5 ppm P2O5, and 10 ppm K2O.

Something you probably just noticed was my use of P2O5 in place of phosphorus and K2O in place of potassium. This is important because that is what those numbers on the bottle actually stand for.

To convert to a real concentration of phosphorus from P2O5, multiple the P2O5 concentration by 0.436 and you will get your true phosphorus concentration.

To convert to a real concentration of potassium, multiple the K2O numbers by 0.83 and you will get your true potassium concentration.


Now, lets clarify what 100 ppm of a liquid fertilizer really is.

Check on the bottle and you should see a weight somewhere. If you've got 1 gallon, it will be around 9.5-13 lbs. Divide that number by 8.34, the density of pure water, to get your specific gravity, SG. Now, we need to do some math to determine how much volume we need to add that will equal 100 ppm of this liquid fertilizer.

Lets assume your fertilizer weighs 10.4 lbs. That's 10.4/8.34 = 1.247 = SG.

Alright, well, now I want to add 100 ppm of that fertilizer. How much volume is it to do that?

100 ppm means to add 100 mg/L. If it were just water, it would be easy as water has a mass of just about 1 g/ml. But it's not. So, we need to do a little extra. 100 mg of this fertilizer with an SG of 1.247. 100mg = 0.1g. It is important that we convert to grams instead of milligrams right here because we want a value in mL instead of uL. 0.1g/1.247SG = 0.080. We need to add 0.080mL/L to get 100 ppm of this liquid fertilizer, and that will give us 2 ppm N, 1 ppm P2O5, and 2 ppm K2O.

Now, if you want 200 ppm of N, you will need to add 10,000 ppm of this liquid fertilizer. 10,000 ppm of this fertilizer is 8mL/L. 8mL/L = 30.3mL/gallon.

Your final solution will then be the following
200 ppm total N
43.6 ppm P (100 ppm P2O5)
166 ppm K (200 ppm K2O)
Click to expand...

I get what your saying but 100ppm of calcium is 100ppm of calcium if i use my ppm meter and dismiss everything else, at first i thought i was making a mistake but now i get what your on about.

Your thoughts on what calmag does to the ratio of nitrogen when added please?
 
Kingrow1

Kingrow1

Well-Known Member
MisterBlah said:
The number one way to cause a calcium or magnesium deficiency is to have too high potassium levels, not phosphorus. Potassium competes with other positively charged ions, like calcium and magnesium.
Click to expand...
Bingo, most veg ferts are higher in potassium than nitrogen these days, im in soil not hydro so hate this high K number.

Calmag makes a difference but only when it contains nitrogen, just adding cal and mag does nothing for me.
 
RM3

RM3

Well-Known Member
MisterBlah said:
The number one way to cause a calcium or magnesium deficiency is to have too high potassium levels, not phosphorus. Potassium competes with other positively charged ions, like calcium and magnesium.
Click to expand...
I feed the holy crap outta em with K and have never had a Mag Def ?

I regularly feed a 7-15-30 mixed equally with a 0-0-50 thru out flower
 
Last edited:
Kingrow1

Kingrow1

Well-Known Member
RM3 said:
I feed the holy crap outta em with K and have never had a Mag Def ?

I regularly feed a 7-15-30 mixed equally with a 0-0-50 thru out flower
Click to expand...
My calmag kicks ass for veg but im not short calmag in either ferts or soil, the only other thing in calmag is nitrogen and most veg ferts are 2-1-2 / 3-1-3 (or there abouts). My calmag brings that upto 3-1-2 and as much as 5-1-2 with its nitrogen.

Now am i seeing the effects of calmag or the calmag making a higher nitrogen fertilizer? I ve used not nitrogen cal and mag and they did nothing, only calmag with nitrogen kicks ass.
 
C

churchhaze

Well-Known Member
Calcium does more to antagonize magnesium than K does, but MisterBlah is right about K also competing with other positive charged ions (Mg++ and Ca++).

This is more straightforward in hydro.
 
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C

churchhaze

Well-Known Member
For hydroponic nutes, a 1 : 0.65 : 1.36 NPK ratio with a Ca:Mg ratio of somewhere between 1 : 0.30 for softer water and 1 : 0.50 for very hard water is what I've found to be the sweet spot.
 
MisterBlah

MisterBlah

Well-Known Member
RM3 said:
I feed the holy crap outta em with K and have never had a Mag Def ?

I regularly feed a 7-15-30 mixed equally with a 0-0-50 thru out flower
Click to expand...
Concentration is important here. Although, I do not ever recommend using that sort of ratio during flower.

One thing to be aware of is that when growing in soil, developing a fertilizer program is a very very different ballgame. You can achieve the same results with two different soils and two very different fertilizer blends. It all depends on what the soil has a high concentration of. On top of all that, soil is more forgiving when it comes to nutrient toxicity.
 
RM3

RM3

Well-Known Member
MisterBlah said:
Concentration is important here. Although, I do not ever recommend using that sort of ratio during flower.

One thing to be aware of is that when growing in soil, developing a fertilizer program is a very very different ballgame. You can achieve the same results with two different soils and two very different fertilizer blends. It all depends on what the soil has a high concentration of. On top of all that, soil is more forgiving when it comes to nutrient toxicity.
Click to expand...
I grow in peat and not only do I recommend my feeding style there are 100's of growers using it and also not having any Mag def's a few of em are soil growers, a few are hydro growers a few use coco and why do we do this ? because it makes for more potent buds
 
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