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I see a lot of new growers are confused about which PPM scale their chosen nutrient company uses. Or they don’t even know there are different scales. I know I didn’t when I first started. Knowing which scale your nutrient and meter manufactures use could potentially save you from major problems down the road. I was poking around on the internet and decided to compile some information in one easy to find thread so the information could be more quickly reference. I did not author all of this information, I simply did the leg work. I’ll sight sources at the end. Of course everyone could just use EC, but where’s the fun in that.
There are many different scales used for different industries around the world and for many different reasons! Did you even know there are more than two scales? The most widely used scales in Hydroponics are the 500 scale, 650 scale and the 700 scale.
What's the difference? The ppm 700 scale is based on measuring the KCl or potassium chloride content of a solution. The PPM 500 is based on measuring the NaCl or sodium chloride content of a solution and is also referred to as TDS - total dissolved solids. Individual nutrient ions have different electrical effects! The true ppm of a solution can only be determined by a chemical analysis. PPMcannot be accurately measured by a CF or EC meter.
A conversion example is as follows;
2.4EC x 500 = 1200ppm (500 scale) or 1200ppm / 500 = 2.4EC
2.4EC x 700 = 1680ppm (700 scale) or 1680ppm / 700 = 2.4EC
If you must grow using ppm (instead of EC), you will need to know the following;
What PPM scale is the book (research material) referring to?
What PPM scale is your meter using?
What PPM scale is the nutrient formula referring to?
For literature, unless the PPM scale is disclosed at the front of the book, the best indicator would be where it was written. The USA mostly uses the 500 PPM scale, Europe and the UK predominantly use the 700 PPM scale, and Australia could be any of them. I know, what the hell right! It gets worse with the meters.
The PPM meter manufacturers are also all over the world, so it stands to reason that the scale they use varies between manufacturers. I’ll list a few of the more popular companies. However, there are tons of elcheepo TDS/PPM meters made in China and it’s anybody’s guess which scale they are using. Sometimes it will be listed in the fine print, but you usually need to hunt for it. I would also recommend avoiding meters that cost less than $25. These meters are poorly made and will not be as accurate as one from a more reputable manufacturer. Plus they will require calibration more often. Quality manufacturers include:
Blue Lab = 500 scale
Milwaukee = 500 scale
Hanna = 700 scale
Oakton = 700 scale
Now that we know the scale our PPM meter is, we need to know what scale the nutrient manufacturers are using. If they are using the same scale as our meter, we’re golden. If not, we need to know so we can adjust the concentration of the solution accordingly. The following is a brief list of common nutrient companies and the PPM scale they use when referencing dosage.
Manufacturer = Scale
Advanced Nutrients=700 scale
Botanicare=700 scale
CES/Cutting Edge Solutions=500 scale
Dutch Master=500 scale
Dyna-Gro=500 scale
FoxFarm=700 scale using dechlorinated tap water
General Hydroponics =500 scale using reverse osmosis water
General Organics =500 scale using reverse osmosis water
House & Garden =700 scale
Humboldt Nutrients=500 scale
Hydro Organics/Earth Juice =500 scale
Nectar for the Gods=700 scale
Rock Nutrients=700 scale
Roots Organics=500 scale
Rx Green Solutions=500 scale using distilled water
Soul=500 scale
Technaflora =500 scale
I have attached a handy conversion chart. This is why I like the Blue Lab Truncheon. It’s basically this chart, wrapped around a stick with lights next to each row to indicate concentration level when placed into a solution.
Hopefully this helped you understand the different scales used. I believe once growers gain a firm understanding of this concept, they can chuck their feeding schedules, begin to read what the plant needs and understand the best way to respond. It will also open up a whole new world of nutrient mix recipes. Happy growing!!
https://www.getbluelab.com/Product+Support_/FAQs.html
https://hannainst.com/knowledge-base#whatistds
http://www.4oakton.com/
http://www.milwaukeeinstruments.com/site/
There are many different scales used for different industries around the world and for many different reasons! Did you even know there are more than two scales? The most widely used scales in Hydroponics are the 500 scale, 650 scale and the 700 scale.
What's the difference? The ppm 700 scale is based on measuring the KCl or potassium chloride content of a solution. The PPM 500 is based on measuring the NaCl or sodium chloride content of a solution and is also referred to as TDS - total dissolved solids. Individual nutrient ions have different electrical effects! The true ppm of a solution can only be determined by a chemical analysis. PPMcannot be accurately measured by a CF or EC meter.
A conversion example is as follows;
2.4EC x 500 = 1200ppm (500 scale) or 1200ppm / 500 = 2.4EC
2.4EC x 700 = 1680ppm (700 scale) or 1680ppm / 700 = 2.4EC
If you must grow using ppm (instead of EC), you will need to know the following;
What PPM scale is the book (research material) referring to?
What PPM scale is your meter using?
What PPM scale is the nutrient formula referring to?
For literature, unless the PPM scale is disclosed at the front of the book, the best indicator would be where it was written. The USA mostly uses the 500 PPM scale, Europe and the UK predominantly use the 700 PPM scale, and Australia could be any of them. I know, what the hell right! It gets worse with the meters.
The PPM meter manufacturers are also all over the world, so it stands to reason that the scale they use varies between manufacturers. I’ll list a few of the more popular companies. However, there are tons of elcheepo TDS/PPM meters made in China and it’s anybody’s guess which scale they are using. Sometimes it will be listed in the fine print, but you usually need to hunt for it. I would also recommend avoiding meters that cost less than $25. These meters are poorly made and will not be as accurate as one from a more reputable manufacturer. Plus they will require calibration more often. Quality manufacturers include:
Blue Lab = 500 scale
Milwaukee = 500 scale
Hanna = 700 scale
Oakton = 700 scale
Now that we know the scale our PPM meter is, we need to know what scale the nutrient manufacturers are using. If they are using the same scale as our meter, we’re golden. If not, we need to know so we can adjust the concentration of the solution accordingly. The following is a brief list of common nutrient companies and the PPM scale they use when referencing dosage.
Manufacturer = Scale
Advanced Nutrients=700 scale
Botanicare=700 scale
CES/Cutting Edge Solutions=500 scale
Dutch Master=500 scale
Dyna-Gro=500 scale
FoxFarm=700 scale using dechlorinated tap water
General Hydroponics =500 scale using reverse osmosis water
General Organics =500 scale using reverse osmosis water
House & Garden =700 scale
Humboldt Nutrients=500 scale
Hydro Organics/Earth Juice =500 scale
Nectar for the Gods=700 scale
Rock Nutrients=700 scale
Roots Organics=500 scale
Rx Green Solutions=500 scale using distilled water
Soul=500 scale
Technaflora =500 scale
I have attached a handy conversion chart. This is why I like the Blue Lab Truncheon. It’s basically this chart, wrapped around a stick with lights next to each row to indicate concentration level when placed into a solution.
Hopefully this helped you understand the different scales used. I believe once growers gain a firm understanding of this concept, they can chuck their feeding schedules, begin to read what the plant needs and understand the best way to respond. It will also open up a whole new world of nutrient mix recipes. Happy growing!!
https://www.getbluelab.com/Product+Support_/FAQs.html
https://hannainst.com/knowledge-base#whatistds
http://www.4oakton.com/
http://www.milwaukeeinstruments.com/site/
