Roddy Conrad

05-31-2008, 09:33 PM

Several of my ponding friends have contacted me privately recently asking for PP dosing calculations. To avoid answering a few hundred private emails and private messages on this subject, instead of giving the answers privately, I promised them to write a thread here for all to use instead.

First let me admit openly that it is better to accurately weigh PP powder on a gram scale if a gram scale that is sufficiently accurate is available. However, to buy a gram scale that is sufficiently accurate is quite expensive, because those cheap ones that claim to measure to the nearest gram really don't perform, and I find those cheap gram scales sometimes weighs 15 grams as 5 grams. So unless you have a really good gram scale that is really accurate, I suggest you simply rely on the old standard teaspoon measure. And I openly admit a teaspoon of PP powder can weigh as little as 5 grams and as much as 9 grams, but usually is fairly close to 7 grams. So I am going to state the dose both in grams and teaspoon equivalents, assuming your average teaspoon of powder weighs 7 grams.

And, NO, I am not going to do research on gram scales and their accuracy, there must be at least 100 brands of gram scales around, some actually performing as advertised, but the cheap ones usually give such misinformation a teaspoon measure is usually more accurate and trustworthy.

Okay, with that introduction, first let me state my calculation methods.

The dose will always be calculated as ppm or parts per million. Since we want the PP powder dose in grams, and the pond dose in ppm, I usually calculate the pond volume in millions of grams, then just multiply the ppm dose times the millions of grams of water to get the PP powder dose in grams. First let us do this for larger ponds that are measured in thousands of gallons, then I will take it a step further and calculate doses for small ponds and glass aquariums.

A thousand gallons of water, when the gallons are USA measure gallons (European and Canadian use a differetn gallon measure) contain 1,000 gallons times 8.3 pounds per gallon times 454 grams per pound = 3.77 million grams. So if we want a 1 ppm dose for a thousand gallons, we need 3.77 grams of PP or about a half teaspoon per 1,000 gallons. Likewise a 2 ppm dose for 1,000 gallons is 2 ppm times 3.77 million grams = 7.54 grams of the powder or about a teaspoon, 3 ppm dose for 1,000 gallons is 3 ppm times 3.77 million grams = 11.31 grams or about 1.6 teaspoons of the powder. If we want a 0.5 ppm dose, and have 1,000 gallons, then 0.5 ppm times 3.77 million grams = 1.89 grams or we need a quarter teaspoon per 1000 gallons or one teaspoon per 4000 gallons. If your pond is a multiple of thousands of gallons, simply multiply the numbers above by the thousands of gallons. Now I will post this and calculate for smaller pond and aquarium volumes.

First let me admit openly that it is better to accurately weigh PP powder on a gram scale if a gram scale that is sufficiently accurate is available. However, to buy a gram scale that is sufficiently accurate is quite expensive, because those cheap ones that claim to measure to the nearest gram really don't perform, and I find those cheap gram scales sometimes weighs 15 grams as 5 grams. So unless you have a really good gram scale that is really accurate, I suggest you simply rely on the old standard teaspoon measure. And I openly admit a teaspoon of PP powder can weigh as little as 5 grams and as much as 9 grams, but usually is fairly close to 7 grams. So I am going to state the dose both in grams and teaspoon equivalents, assuming your average teaspoon of powder weighs 7 grams.

And, NO, I am not going to do research on gram scales and their accuracy, there must be at least 100 brands of gram scales around, some actually performing as advertised, but the cheap ones usually give such misinformation a teaspoon measure is usually more accurate and trustworthy.

Okay, with that introduction, first let me state my calculation methods.

The dose will always be calculated as ppm or parts per million. Since we want the PP powder dose in grams, and the pond dose in ppm, I usually calculate the pond volume in millions of grams, then just multiply the ppm dose times the millions of grams of water to get the PP powder dose in grams. First let us do this for larger ponds that are measured in thousands of gallons, then I will take it a step further and calculate doses for small ponds and glass aquariums.

A thousand gallons of water, when the gallons are USA measure gallons (European and Canadian use a differetn gallon measure) contain 1,000 gallons times 8.3 pounds per gallon times 454 grams per pound = 3.77 million grams. So if we want a 1 ppm dose for a thousand gallons, we need 3.77 grams of PP or about a half teaspoon per 1,000 gallons. Likewise a 2 ppm dose for 1,000 gallons is 2 ppm times 3.77 million grams = 7.54 grams of the powder or about a teaspoon, 3 ppm dose for 1,000 gallons is 3 ppm times 3.77 million grams = 11.31 grams or about 1.6 teaspoons of the powder. If we want a 0.5 ppm dose, and have 1,000 gallons, then 0.5 ppm times 3.77 million grams = 1.89 grams or we need a quarter teaspoon per 1000 gallons or one teaspoon per 4000 gallons. If your pond is a multiple of thousands of gallons, simply multiply the numbers above by the thousands of gallons. Now I will post this and calculate for smaller pond and aquarium volumes.