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Discussion Starter · #1 ·
buy new ones? right!

So, I have dry ferts at home and want to reuse the bottles. I have not found a useful, straight to the point answer.

How much dry powder will each bottle need ( 500 ml, each pump is 1 ml ). What I did found is that it has to be very concentrated, so lets say I want to dose with each pump 5 gallons of water ( 1 pump = dosing 5 gallons)

some suggested to buy a digital scale and measure the amounts, no problem with that, but how much dry ferts should I add?

thanks for any help, I know this will help a lot of us
 

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Hello my friend.

I will keep this short and to the point.

Dry ferts....check

Micro scale hundredths scale (thousandths even better)....purchase

graduated pumps (you know how much fluid they hold)....check


Answer: Download yourself 'Chuck's Planted Aquarium Calculator' via Googizzle

Chucks Planted Aquarium Calculator

It will show you the way....
 

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Hmm looks relatively easy to deconstruct in terms of its NPK.

All of this will be working in 1L batches, you can half to get 500ml later. I'm not about to correct for density at the moment; it'd take me a while longer to calculate that and I'm a bit tired right now. You may want to add 2-5% to any of these numbers. You could probably even weigh some pfertz to get a rough estimate if you wanted. You'll also want to follow along with these equations by looking up the molar mass of the compounds we're working with.

Nitrogen bottle:
5% K2O
1.75% NO3

Ingredients: Urea and KNO3

Well there's no potassium in urea, so we can find out the quantity of it by figuring out however much KNO3 doesn't take up.

First order of business is to convert K2O to K+:

=39.09831/(39.09831+(30.9737622*2)
=0.386936386

So for every mg K2O there's 0.386936386 mg K+

It's 5% so...

=(1000/100*5)*0.386936386
=19.34681931

Total KNO3: 19.34681931g/L

So how much urea do we need to add? First lets find out how much N is in the bottle by converting NO3 to N.

First the conversion factor:

=14.00672/62.00501
=0.225896585

So for every 1g of NO3 there's 0.225896585 of N.

Next up, lets figure out how much NO3 is in the bottle and convert:

=(1000/100*1.25)*0.225896585
=2.823707313

So we need to get 2.823707313g more of N into this thing, and we need to do it through urea. Urea is (NH2)2CO. In terms of molar mass, that's 60.06g/mol. N is 14.00672g/mol.

=2.823707313*(60.06/14.00672)
=12.10789258

So that's 12.10789258g of urea.

Contents of 1L of pfertz N:
KNO3: 19.34681931g
(NH2)2CO.: 12.10789258g

For mixing this, as with any of the rest, you'll have to tinker with the order. I'm not sure what sort of issues with precipitates you might run into since I don't play with urea outside of the mens room.

The other two are way easier. The P bottle is nothing but DI H2O and KH2PO4. It lists as 0.25% K2O.

So first lets figure out how much K2O that is, and convert it to the equivalent K+:
=(1000/100*.25)*0.386936386
=0.967340965

That's 0.967340965g of K+

Now how much KH2PO4 does that require?
=0.967340965*(136.0856722/39.09831)
=3.366929299

Pfertz P contains 3.366929299g

Contents of 1L of Pferts P:
KH2PO4: 3.366929299g

And now for the K+, which is more of the same method. In this case it's all K2SO4 and listed as 5.1% K2O.

Convert % of K2O to quantity of K:

=(1000/100*5.1)*0.386936386
=19.73375569

So 19.73375569g of K, now how much K2SO4 does that mean?

=19.73375569*(174.25984/78.19662)
=43.9763395

Contents of 1L of Pferts K:
K2SO4: 43.9763395g


And there you have it. An approximation of pfertz NPK. When I have a bit more energy I may correct for density, and take a run at the micros. If anyone sees any errors, let me know. The rechecked, refined version is something I'll probably post up over on barrreport.com or something.

Enjoy :)

-Philosophos
 

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Hmm looks relatively easy to deconstruct in terms of its NPK.

All of this will be working in 1L batches, you can half to get 500ml later. I'm not about to correct for density at the moment; it'd take me a while longer to calculate that and I'm a bit tired right now. You may want to add 2-5% to any of these numbers. You could probably even weigh some pfertz to get a rough estimate if you wanted. You'll also want to follow along with these equations by looking up the molar mass of the compounds we're working with.

Nitrogen bottle:
5% K2O
1.75% NO3

Ingredients: Urea and KNO3

Well there's no potassium in urea, so we can find out the quantity of it by figuring out however much KNO3 doesn't take up.

First order of business is to convert K2O to K+:

=39.09831/(39.09831+(30.9737622*2)
=0.386936386

So for every mg K2O there's 0.386936386 mg K+

It's 5% so...

=(1000/100*5)*0.386936386
=19.34681931

Total KNO3: 19.34681931g/L

So how much urea do we need to add? First lets find out how much N is in the bottle by converting NO3 to N.

First the conversion factor:

=14.00672/62.00501
=0.225896585

So for every 1g of NO3 there's 0.225896585 of N.

Next up, lets figure out how much NO3 is in the bottle and convert:

=(1000/100*1.25)*0.225896585
=2.823707313

So we need to get 2.823707313g more of N into this thing, and we need to do it through urea. Urea is (NH2)2CO. In terms of molar mass, that's 60.06g/mol. N is 14.00672g/mol.

=2.823707313*(60.06/14.00672)
=12.10789258

So that's 12.10789258g of urea.

Contents of 1L of pfertz N:
KNO3: 19.34681931g
(NH2)2CO.: 12.10789258g

For mixing this, as with any of the rest, you'll have to tinker with the order. I'm not sure what sort of issues with precipitates you might run into since I don't play with urea outside of the mens room.

The other two are way easier. The P bottle is nothing but DI H2O and KH2PO4. It lists as 0.25% K2O.

So first lets figure out how much K2O that is, and convert it to the equivalent K+:
=(1000/100*.25)*0.386936386
=0.967340965

That's 0.967340965g of K+

Now how much KH2PO4 does that require?
=0.967340965*(136.0856722/39.09831)
=3.366929299

Pfertz P contains 3.366929299g

Contents of 1L of Pferts P:
KH2PO4: 3.366929299g

And now for the K+, which is more of the same method. In this case it's all K2SO4 and listed as 5.1% K2O.

Convert % of K2O to quantity of K:

=(1000/100*5.1)*0.386936386
=19.73375569

So 19.73375569g of K, now how much K2SO4 does that mean?

=19.73375569*(174.25984/78.19662)
=43.9763395

Contents of 1L of Pferts K:
K2SO4: 43.9763395g


And there you have it. An approximation of pfertz NPK. When I have a bit more energy I may correct for density, and take a run at the micros. If anyone sees any errors, let me know. The rechecked, refined version is something I'll probably post up over on barrreport.com or something.

Enjoy :)

-Philosophos

I am dizzy and need to go lay down.....
 

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Lots of science, but no density compensation yet so the numbers are wrong. Density is going to make a huge differenced; don't go mixing anything yet based on the numbers I posted. I'm working on a more complete examination of pfertz in terms of cost compared to DIY and seachem's line of products (very similar packaging method) and I'll post a link to it when I'm done.

-Philosophos
 

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Discussion Starter · #8 ·
Yeah please! Once you figure it out people like me can just get the amounts, mix them and dose using the pfertz bottles.
 

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Nitrogen bottle:
5% K2O
1.75% NO3

Ingredients: Urea and KNO3

Well there's no potassium in urea, so we can find out the quantity of it by figuring out however much KNO3 doesn't take up.

First order of business is to convert K2O to K+:

=39.09831/(39.09831+(30.9737622*2)
=0.386936386

So for every mg K2O there's 0.386936386 mg K+

It's 5% so...

=(1000/100*5)*0.386936386
=19.34681931

Total KNO3: 19.34681931g/L
This seems to be incorrect. K2O contains 83% of K, not 38%. The potassium is present in 4.15% in PFertz N.
If one dissolves KNO3: 19.34681931g/L it will be only 0.722% of K.
 
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