If you measure ppm's, READ THIS!

I was having problems hitting my target ppm when mixing to manufacturers specs. I posted a question, and bloomingdale81 educated me about different ppm conversions, .5 and .7. After doing some research, I found a very useful chart that I re-posted and thedillestpickle suggested making it a separate thread. So here you go


senseless
06-21-2006, 02:30 AM
i think this will help a lot of growers.

ppms are confusing as hell i think. let me try and explain.

ppm is a calculation of EC or CF.

CF= EC multiplied by 10. ex, 1.0ec x 10 = 10CF

ec = CF divided by 10. ex, 10CF divided by 10 = 1.0 EC

the problem with ppm is that its not a standardized way of taking readings so almost every product manufacture has a different way of measuring ppm. in other words thier ppm conversion factor.

a .7 factor is actually called a 442 conversion factor wich is approximately 700 multiplied by EC.

a .5 factor or the NaCl conversion factor wich is approximately 500 multiplied by EC.

depending on wich type of TDS meter you use it will use either a .5 or .7 conversion factor. this is why some people get different readings with different meters.

lets say your nutreint solution was 1.0 EC
using the .7 conversion factor your ppm would be 700.
using the .5 conversion factor your ppm would be 500.

heres a conversion chart i made up,
(EC)------(PPM.5)---------(PPM.7)-------(CF)
.4---------200-------------280-----------4-----seedling/ rooted clones
.6---------300-------------420-----------6-----
.8---------400-------------560-----------8-----veg
1.0--------500-------------700----------10
1.2--------600-------------840----------12
1.4--------700-------------980----------14
1.6--------800-------------1120---------16-----aggressive
1.8--------900-------------1260---------18
2.0--------1000------------1400---------20-----super aggressive
2.2--------1100------------1540---------22
2.4--------1200------------1680---------24-----be carefull after this point!!
2.8--------1400------------1960---------28
3.2--------1600------------2240---------32
3.6--------1800------------2520---------36
4.0--------2000------------2800---------40
4.4--------2200------------3080---------44
i suggest everone start using EC or CF. its simple, standard, and most parts of the world use it.

Did everyone see this?

look again?

Helpful to the new grower. Bump

very helpful, thank you Redbird for the tip

Ec is better but I like my ppm. I have my nutes down. The biggest problem I see is people trying to do what manufactures recamend. There here to sell so why not bump everything up to the point it won't kill a tamato. And call it good. And the customer uses more then needed. I have a mix of alot of nutes so there is only one thing to go by. The ppm I have set. But very good info for new growers.

It's also worth remembering that meters that read TDS directly typically use one of three conversion conventions. Most Hanna read 500 ppm for EC 1.0. Most Oakton read 640 ppm, and the Bluelab Truncheon reads 700 per. cn

USA 1 ms/cm (EC 1.0 or CF 10) = 500 ppm
European 1 ms/cm (EC 1.0 or CF 10) = 640 ppm
Australian 1 ms/cm (EC 1.0 or CF 10) = 700 ppm

For example,

Hanna, Milwaukee 1 ms/cm (EC 1.0 or CF 10) = 500 ppm
Eutech 1 ms/cm (EC 1.0 or CF 10) = 640 ppm
Truncheon 1 ms/cm (EC 1.0 or CF 10) = 700 ppm

Click to expand...