# Re: "Liquid potassium calculations"

```Matt:

You need to add about 1 tablespoon of 25% Potassium solution to 60 Gallons
of water to get 20 ppm.

K1            = Concentration of Potassium in fertilizer = 25%/100% = 0.25
Dose        = Volume of fertilizer in milliliter (mL)
V               = Volume of aquarium in Liters (L)
K2             = Concentration of Potassium in aquarium (in ppm)
1 Gallon   = 3.79 Liters
1 mL/L      = 1000 ppm
1 tablespoon = 14.7 mL
* = multiplication sign

1 mL out of 1 Liter is 1 part in 1000, or 1000 parts per million (ppm)
1 mL of 25% solution in 1 Liter of water is 250 ppm

Mathematically:  (K1 * Dose *1000)/V = K2

Solving for Dose yields:  Dose = (K2 * V)/(K1*1000)

If,
K1 = 0.25
K2 = 20 ppm
V = 60 gallons = about 227 L

Dose = (20*227)/(.25 * 1000) = 18 mL

The water drop size from most eye-droppers is 0.05 mL, that is 20 drops will
give you 1 mL of solution.  A table spoon is about 15 mL, a teaspoon about 5
mL.

Joe K In Takoma Park, Maryland

Blooming in the yard today:  foxglove, moth mulleins, iris

```