Tds Meter Data - What Does It Mean?

Budzy · Apr 9, 2016

My first grow and recently switched to AN nutes at which time pH went nuts so i purchased this TDS meter and not sure what it is telling me. my metrics for the first feeding were as follows:

Aged tap water = 035 ppm., 7.1 pH. (i think this is my "base"?)
Nute Mix = 756 ppm., 5.9 pH. (think ph pen is off a .tic and believe this is actually 6.0)
~20% Runoff = 970 ppm., 5.9 pH. (off a .tic)
I allowed it to sit in the runoff for two hours to ensure no dry spots, measured again and got 985 ppm.

I am using soil beginning week 6 of flower. What is this telling me?

jumpincactus · Apr 9, 2016

https://en.wikipedia.org/wiki/Total_dissolved_solids

Budzy · Apr 9, 2016

Thanks but am afraid that did not help much. I understand what it is. just need a practical example of using the readings.

jumpincactus · Apr 9, 2016

I guess I'm not sure what your question is, can you be more specific?

ken dog · Apr 9, 2016

If it's any help, the total dissolved solids is on the 500 scale... Which means that 500 TDs, is 1 EC.

ken dog · Apr 9, 2016

Essentially, what it is doing, is telling you the concentration of nutrients in your solution.

Some people don't go much higher than 1 EC during the entire grow, and some people will push it up to 2 EC and a little beyond.

Budzy · Apr 9, 2016

jumpincactus said:
I guess I'm not sure what your question is, can you be more specific?

Looking for something like: "that means she is leaving behind nutes and has too much salt buildup and you should flush it."
or
"The ppm at week 6 flower should be xxxxppm. and she it too low, you should add more nutes."

ken dog said:
If it's any help, the total dissolved solids is on the 500 scale... Which means that 500 TDs, is 1 EC.

Which brings up another question. How do i tell which scale my tds meter is using for ec conversion, 0.5 or 0.7?

Where can i find a chart or something showing the ideal ppm values for AN nutes in soil at various growth stages?

ken dog · Apr 9, 2016

TDS means .5

PPM means .7

Here is a feeding schedule that current culture recommends...
.

A.Sherman · Apr 9, 2016

I see my bluelab meter seems to be calibrated or set to 500 which im assuming is the .5 your talking about, does that mean when i mix up what i thought was a 600ppm solution its really something else?...TDS???

ken dog · Apr 9, 2016

A.Sherman said:
I see my bluelab meter seems to be calibrated or set to 500 which im assuming is the .5 your talking about, does that mean when i mix up what i thought was a 600ppm solution its really something else?...TDS???

600...right?

If it is on the .5 scale, then you are just above 1 EC.

If you are on the .7 scale, then you are just below 1 EC.

....1 EC equals 500 on the .5 scale... And...1 EC equals 700 on the .7 scale.

A.Sherman · Apr 9, 2016

So how do you know which it is if im just told to feed 600? Why are there 2 scales?

Budzy · Apr 9, 2016

A.Sherman said:
So how do you know which it is if im just told to feed 600?

That is what i would like to know! Also, how do you measure ferts that way? I am used to xx tsp./Gal.

Why are there 2 scales?

That would have made this way too easy.

ken dog said:
TDS means .5

PPM means .7

Here is a feeding schedule that current culture recommends...
.

Thanks man! I will go check that out.

ken dog · Apr 9, 2016

A.Sherman said:
So how do you know which it is if im just told to feed 600? Why are there 2 scales?

A good rule of thumb is to go with the 700 scale so you don't over feed.

Savage Henry · Apr 9, 2016

ken dog said:
A good rule of thumb is to go with the 700 scale so you don't over feed.

I agree, more precision with the 700 scale.

jumpincactus · Apr 9, 2016

The ppm 500 scale is based on measuring the KCl or potassium chloride content of a solution. The ppm 700 is based on measuring the NaCl or sodium chloride content of a solution. Individual nutrient ions have different electrical effects! The true ppm of a solution can only be determined by a chemical analysis. ppm cannot be accurately measured by a CF or EC meter. They are present on Bluelab products as a conversion guide only. The conversion is as follows; 2.4 EC x 500 = 1200 ppm (500 scale) or 1200 ppm / 500 = 2.4 EC 2.4 EC x 700 = 1680 ppm (700 scale) or 1680 ppm / 700 = 2.4 EC If you are wanting to measure your solution in ppm, you will need to know the following: • What ppm scale is your meter using? • Which calibration standard should you use for your meter? • What ppm scale is your nutrient referring to?

Budzy · Apr 10, 2016

Well, I know that AN nutes are referring to the 700 scale.
This is the TDS pen i have
I do not see where it tells me which scale the pen is using. and there is some info there about it's calibration but am not sure if that is what you are referring to... getting a bit over my head now.

I gave her 2 gals. 6.3pH Tap (036ppm.)
Runoff = 975ppm., 5.9pH.

Last feeding the runoff was 970ppm... which means what?

here is a current photo if anyone would like to see her:

sixstring · Apr 10, 2016

Wow i got confused at all those responses lol.i have that meter,it reads 500 scale so 500ppm is 1.0ec
975ppm is not bad for that size plant.my thoughts would be feed at around 400 to 500ppm total for a few and continue to monitor the runoff.if it starts to drop alot just raise the feed # a lil .plant dont look too bad to me but i kinda lost track reading all this jazz lol

sixstring · Apr 10, 2016

Soil ph should be in the 6.2 to 6.6 range also so you can raise that by using a tad higher ph feeds.i see your in wk 6 so i wouldnt get all hung up on corrections this late.gl

Budzy · Apr 10, 2016

Thanks sixstring, that's the info i was looking for but i still do not understand when you say "feed at around 400 to 500ppm". I have been measuring like 4.8 tsp./2 gals aged tap. how do i measure it to obtain the desired ppm? especially using the additional amendments.

and it does not matter what i adjust the ph to, runoff is always 5.9 with this ph perfect stuff.

Budzy · Apr 10, 2016

I found this for any others using AN nutes in soil:

https://forum.grasscity.com/threads/advanced-nutrients-how-to-directly-from-an.441401/

Tds Meter Data - What Does It Mean?

Tds Meter Data - What Does It Mean?

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Tds Meter Data - What Does It Mean?

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