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please xplain conversion ppm of "variable, 0.56 to 0.72"

inreplyavalon

inreplyavalon

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My meter which is a HI9813-0 GroChekPortable made by Hanna has a ppm conversion range of " variable, 0.56 to 0.72 "

I have always read that hanna are the .5 conversion type meter but when i am reading and comparing my ppm and ec with the meter it seems that it is .7
example 1.0 ec = 700 ppm

anyone have any clue about this?

Thanks and happy weekend!
 
inreplyavalon

inreplyavalon

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"""EC/TDS CONVERSION FACTOR
The TDS value in aqueous solutions is directly proportional to the conductivity. The ratio between the two parameters de- pends on the solution. HI 8732 has a variable conversion factor from 0.56 to 0.72 according to the TDS442 curve, which represents the best approximation for the TDS measurement for applications such as hydroponics, fertilizer mixtures, farming and ground water.""""

This was found in a pdf file about the meter. clears it up and confuses things all at the same time. Sounds like a sliding scale. I am going to go with the .7 conversion because that is what it seems to be usually when i am doing the math, though most literature i find says hanna uses .5 not always i guess
 
stonedar

stonedar

Macro-aggressor
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what in the hell is a TDS442 curve ?

as a long time Hanna user (HI98129) you got me bugging a little, I'm going researching too.
 
MIway

MIway

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NaCl Scale... 1.0ec = 500ppm


442 Scale... 1.0ec = 720ppm



Pretty easy... 1.0ec is the same, just a different ppm, but the strength is still what it is... nothing changes there.

Different opinions as to which ppm scale is 'better'... but I like 700 as it gives a little better resolution in measurements... but it's still 1.0ec, ya know?
 
FreezerBoy

FreezerBoy

Was blind but now IC Puckbunny in Training
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No pen can measure "PPM' or "TDS"; all they can measure is EC. However, plants are illiterate, they don't know that "PPM" and "TDS" are nonsense. As long as you can track numbers up or down, you're golden. Pick any conversion factor and stick with it. Rather than try to match charts on the web, (charts that have never met you or your plants) start with a 1/2 strength solution and use EC and pH to communicate with the plant directly as to what it wants.

EC is typically measured in mS/cm (millisiemens per centimeter). There's also µS/cm (microsiemens per centimeter) Just like 1 kilometer=1000 meters, 1mS=1000µS. Example: 1187µS=1.2mS. If you want "better resolution in measurements" dump "PPM" and "TDS" for EC in µS.
 
inreplyavalon

inreplyavalon

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well thats easy. Thanks for explaining miway. Not sure why they dont just say that, instead of saying, "factor from 0.56 to 0.72 according to the TDS442 curve"
but i am not going to make things more confusing for myself.
1.0 = 720 is inline with my math
 
FreezerBoy

FreezerBoy

Was blind but now IC Puckbunny in Training
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DrLongbottom said:
If you are on this website you should be using a .7 conversion. DLB
Click to expand...

You should be using EC.

700 is no more standard than 500, 640, 650, 700, 728 or any of the other half dozen or more "conversions." "PPM" is bad enough without using 7s. Using 5s is much easier. Using no conversion is easier still.
 
DrLongbottom

DrLongbottom

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I do use EC myself. I have a truncheon and it displays EC , .5 , and .7 conversion. As far as standards go....You will find that .7 is the conversion that standard nute recipes are based if given a ppm value instead of EC.
Go with the .5 conversion on ppm and you will run the risk of frying your garden. Good luck ive got nothing more. DLB
 
FreezerBoy

FreezerBoy

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DrLongbottom said:
Go with the .5 conversion on ppm and you will run the risk of frying your garden.
Click to expand...

Frying your garden has nothing to do with a standard 500 conversion. It's from trying to match charts that have never met you, your plants, your cab, your lamp, your media....

Ask your plants what they want. They'll never lie. Charts lie through their teeth.
 
MIway

MIway

Registered User
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^^^ but to be fair... if someone is giving recommendations in ppms, and under the 700 scale... and the other dude has a ppm pen set to 500... then there might be a problem... a 1.0 vs a 1.4. and that stems from simple conversion... and it would seem this type of stuff happens a lot over the forums & irl.

Just like the Hubble & metric conversions... neither ruler was broke, just converting between the two.
 
DrLongbottom

DrLongbottom

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Freezerboy...you seem to be missing my point. If someone reads a thread on this site where so and so says use 1000ppms of said brand nutrient. If you mix to 1000ppm on a .5 conversion to find a 1000ppm you will be actually running much higher ppm on the .7 conversion scale. My point is valid if someone is trying to copy anothers recipe. If the person giving the recipe is using the .7 standard and the person copying the recipe used .5 conversion, the copycats ppms will be higher than givers ppms. This is the reason we have a consensus to use .7 as the conversion factor when giving nute recipes based on ppm. Yes ppm is not the gold standard (EC is the way to go), but i find the majority of growers do not use the EC standard in the states, so to clarify for confusion if you are given a recipe based on ppm, always use the .7 conversion. Based on this convention that was decided upon by some higher powers that we would use a .7 conversion for our formulas if written in ppm. If it had been decided we would use the .5 conversion then that would be the standard in our industry....but it is not. Yes when reading new recipes and formulas and trying to adapt them to your garden it can be difficult to get the same numbers to work for everyone, but, that does not change the fact of how we come to the conclusion of those numbers, we follow set standards to make these transitions as easy as possible. Lastly in defense of ppm over EC.....with ppm you can micro manage your total disolved solids where as EC will always be a bit broader of a range. Puff Puff DLB
 
FreezerBoy

FreezerBoy

Was blind but now IC Puckbunny in Training
Veteran
DrLongbottom said:
If someone reads a thread on this site where so and so says use 1000ppms of said brand nutrient.
Click to expand...

I get your point. You missed mine. If the "chart" says 1000 PPM then, under no circumstances do you feed at 1000 PPM. Feed at 330-500 PPM and then ask the plants how they feel about it. This is why we chart EC and pH and never read charts that know nothing about what we're doing.
 
DrLongbottom

DrLongbottom

Well-known member
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I do not agree with that. If I tell you to make a solution of 1000 ppms of Botanicare Power series in a rez for a hydro application, You can be damn certain i am basing it on a .7 conversion and that it is going to work. As far as trusting just anyones advice, that's the conundrum all new growers face. It is not easy to find a Mentor. As far as following charts, I'm not sure if you mean a feed schedule offered up by an experienced grower, or what a nutrient manufacturer may put on the label of a bottle. If following a good grower....you are not going to cut his recipe at all you will follow it pretty close to the letter. If you mean the labels....then yes always cut back at least 1/2 to start. This discussion has two different angles it can be viewed upon....Im looking at it as copying info from a good grower, not a nutrient recommendation. DLB
 
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