# [Wet Thumb Forum]-Help with working out ppm



## Hispid (Feb 3, 2005)

I have a product from Canna made in Holland called PK 13-14. I'm trying to work out how much gives me what ppm of P and/or K in a 20 litre bucket. The label says it has P2O5 13% and K20 14% in a 500ml bottle. The balance I presume is water. Can anyone help me out? My chemistry isn't up to it.

Cheers Tony


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## Hispid (Feb 3, 2005)

I have a product from Canna made in Holland called PK 13-14. I'm trying to work out how much gives me what ppm of P and/or K in a 20 litre bucket. The label says it has P2O5 13% and K20 14% in a 500ml bottle. The balance I presume is water. Can anyone help me out? My chemistry isn't up to it.

Cheers Tony


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## Dr.T. (Jul 23, 2003)

Is this PK 13-14 a solid or a liquid?? This will help.

Jeff (Dr.T.)
---------------------------
Tank info in profile
29 gallon tank (updated: 9/21/03)
65 gallon tank (updated: 9/21/03)


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## Hispid (Feb 3, 2005)

It's a solution. As I said above I presume the balance (after 13%P2O5 and 14% K2O) is water although on the bottle it doesn't say.

Cheers Tony


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## Roger Miller (Jun 19, 2004)

Tony,

To convert K2O to K, multiply K20 by 0.83
To convert P2O5 to PO4, multiply by 1.3

The solution is then about 17% PO4 and 12% K

This is probably all provided by a mixture of KH2PO4 and K2HPO4 in approximately 1:2 molecular ratio. The ratio may have been selected to get a desireable pH as much as to get a given ratio of potassium to phosphorus.

1 ml of this solution in 20 liters will give (very rougbly):

0.17 grams PO4/20 liters = 8.5 ppm
0.12 grams K/20 liters = 6 ppm

This calculation assumes the solution weighs 1 gram/ml -- the correct value for water. The solution is probably heavier than water, so the concentrations above would be low-end estimates.


Roger Miller

"The indispensible first step to getting the things you want out of life is this: Decide what you want" -- Ben Stein


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## Hispid (Feb 3, 2005)

Thanx for your help. Boy have I been overdosing. Guess that explains the nasty BGA outbreak. Just to make sure, if 1ml gives me 8.5ppm in 20litres then 1ml gives me c.1ppm in my 180 litre tank?

Cheers Tony


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## Dr.T. (Jul 23, 2003)

Not sure if you're saying 0.1 or 1.0, but it's 1.0 (approx - c.







)

Jeff (Dr.T.)
---------------------------
Tank info in profile
29 gallon tank (updated: 9/21/03)
65 gallon tank (updated: 9/21/03)


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## Roger Miller (Jun 19, 2004)

Yes, about 1 mg/l in 180 liters of water.

Roger Miller

"The indispensible first step to getting the things you want out of life is this: Decide what you want" -- Ben Stein


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