Don't drink water pipe water.
The idea is simple. Plant an extra row of vegetables, and donate the harvest to your local food bank or shelter.
How to calculate PPM:
PPM is an abbreviation for "Parts per Million", a often misunderstood and misused term of some ill repute. To clarify, I mean one part of a substance to a million parts of solution, a 1 to 1,000,000 ratio.
Nutrient solutions are mostly water, with a little bit of fertilizer added.
Water is considered to be the solvent since it is what the nutrient solutes are dissolved into to form the nutrient solution. The nutrient solution is considered to be aqueous because the primary component is water. How much is added determines the concentration.
PPM is a measure of concentration, and is used to determine how much of a nutrient should be added to reach a given nutrient level.
To keep things simple, I'll walk you through the calculations using a liter of water for the solvent. The end result can be multiplied by 3.78541 to calculate for a gallon. Each 5 ml increment is marked for the nutrient solutes, which is an even swap for a teaspoon (3 teaspoons to the tablespoon). Note it will allow for non water soluble nutrient mixtures.
So let's get started:
Gentle Reader, there is a theoretical liter of crystal clear water in cyberspace awaiting you. What would you like to add?