Why does it seem there is such a difference in nutrient strenghts between the growing community?

[Jimdamick]

Yes. And that calling a tds meter a ppm meter is like calling an EC meter a micro-siemens meter, or a speedometer a mile meter. A ppm meter is an EC meter sold as TDS meter.

For an individual grower it doesn't matter that much, but when comparing with other growers EC should be used because the difference between 0.5 factor and 0.7 factor can be quite large.

Here's another good reference for completeness:
http://www.milwaukeetesters.com/pdf/ph-ec_info.pdf

One way or the other, the meter measure the nutrients in the water, and relays that information in a multitude of descriptions. Like a language. Same info, different descriptions. That's why I like PPM, because the ranges are so dramatic in different EC measurements. 700 ppm is 700 ppm, whereas there is an average of 300 ppm difference between the 3 ranges ranges used in EC formulas (.50/.64/.70). I just prefer ppm, seems more accurate

 

[Sativied]

I just prefer ppm, seems more accurate

That's actuallly why I bought a hanna 'ppm meter' from the US instead of an EC version, so I totally understand what you're saying, but while it seems more accurate, it is not. For practical purposes they are as accurate because the accuracy is from the physical meter and not the units it uses to display the results. They are theoretically less accurate because that conversion is a rounded guesstimate. They all measure EC at a certain accuracy, converting that to ppm (which your ppm meters do too) doesn't make it any more accurate.

700 ppm is 700 ppm,

A cruyfian expression. The ball is round. True but what matters is what 700 ppm reflects. It's actually the EC that is constant across meters and growers.

When you put X ml nutrients in a liter the meter detects a certain EC value. Depending on the brand and conversion factor used, that results in three different ppm values.

For example 700 ppm on Hanna is 1.4EC, 700ppm on Eutech is roughly 1.1EC, on Truncheon 1.0EC.

The value 700 remains 700 yes, but they all three reflect a different amount nutes in the same amount of water. Which is what it's all about. So based on the ppm alone and not knowing the conversion factor you cannot know the EC, which is really what you are measuring despite displaying it as ppm.

Let me put it this way: Someone running 700ppm on a hanna uses 40% more nutrients than someone with 700ppm on a truncheon. While if they both used the same EC we can tell they use the same amount of nutrients per liter water. Apart from accuracy differences between brands and miscalibration but that applies regardless of how you display the measured EC.

 

[jarvild]

Thanks everybody.
I guess my question is why can I grow very successfully with 1.0 -1.5 at a .5 conversion as the top of my range and yet the next grower is starting his seedlings at 1.5 and going as high as 2.8.

 

[Alaric]

The trays in that bloom room are actually 16" up off the floor. Ten foot high ceilings in there
I try to allow 3' in between the lights and the plant canopy, when plants are mature.
I have DE's in rooms that are 8'high ceilings. The trays in those rooms are just up high enough to put an elbow on 1" drainage tubing. The drainage tubing is plumbed out of the room(through the exterior wall)

fingers crossed while asking this question.

I hope---- I hope you ( or anyone else) has a light meter running DE lights can tell me at what distance below is 10K fc (sunlight intensity).

btw---- aren't 10' ceilings wonderful?

A~~~

 

[Alaric]

That's actuallly why I bought a hanna 'ppm meter' from the US instead of an EC version, so I totally understand what you're saying, but while it seems more accurate, it is not. For practical purposes they are as accurate because the accuracy is from the physical meter and not the units it uses to display the results. They are theoretically less accurate because that conversion is a rounded guesstimate. They all measure EC at a certain accuracy, converting that to ppm (which your ppm meters do too) doesn't make it any more accurate.


A cruyfian expression.

So based on the ppm alone and not knowing the conversion factor you cannot know the EC, which is really what you are measuring despite displaying it as ppm.

Let me put it this way: Someone running 700ppm on a hanna uses 40% more nutrients than someone with 700ppm on a truncheon. While if they both used the same EC we can tell they use the same amount of nutrients per liter water. Apart from accuracy differences between brands and miscalibration but that applies regardless of how you display the measured EC.

Excellant post as usual

What does "crucian expression" mean?

My take on this nute strength discussion:

I've run constant circulation in tubes (no medium) at high PPMs 1500--1800 (.7) with satisfactory yields but had a noticeable metallic taste.

I've run the same system------and same girls at 1000 ppm all the way through -----with no noticeable yield decrease-----and no more metallic taste. I'm not suggesting you couldn't run lower----just never tried it

(link in my sig if any interest)

A~~~

 

[Aeroknow]

fingers crossed while asking this question.

I hope---- I hope you ( or anyone else) has a light meter running DE lights can tell me at what distance below is 10K fc (sunlight intensity).

btw---- aren't 10' ceilings wonderful?

A~~~

Yeah, 10' ceilings are badass.
I do have an old footcandles light meter actually. Give me a day or two, to read the sun, and then compare to my DE's.

 

[Sativied]

What does "crucian expression" mean?
~

Cruyffian, from Johan Cruyff, most famous dutch soccer player, who recently passed away: http://www.theguardian.com/football/2016/mar/24/johan-cruyff-dies-aged-68-holland-football-legend

He had his own way of talking and typical expressions like 'when we got the ball, they can't score' and many tautologies.

 

[Aeroknow]

fingers crossed while asking this question.

I hope---- I hope you ( or anyone else) has a light meter running DE lights can tell me at what distance below is 10K fc (sunlight intensity).

btw---- aren't 10' ceilings wonderful?

A~~~

this is what I get at exactly 3' below the light.

Wish I had a par meter

 

[Alaric]

this is what I get at exactly 3' below the light.
View attachment 3657563
Wish I had a par meter

Perfect -----mucho thanks for your effort

If that reading is near 5000 fc? then my conclusion:

Singled ended 1K HPS horitulux in a 27" X 24" reflector.

16" directly below is 10,000 fc (full sunlight intensity)-----so at 32" is 2500 fc.

Did this make sense ? about the penetration.

 

[Aeroknow]

Perfect -----mucho thanks for your effort

If that reading is near 5000 fc? then my conclusion:

Singled ended 1K HPS horitulux in a 27" X 24" reflector.

16" directly below is 10,000 fc (full sunlight intensity)-----so at 32" is 2500 fc.

Did this make sense ? about the penetration.

Yeah I got ya. If I could give you another reading 6' away I would.
That same reading on that meter is just about where I like to see it with 1000w hps single endeds at 24" away. I use that meter to check my bulbs intensity. Allowed me to spot an old bulb, or a fading cap on my older magnetic ballasts.
I would love to have a par meter, but I used this 15 yo meter to setup my first DE. When I saw it read that high at 3' away, I was fucking blown away. Still am
That old school fc meter allowed me to scope out the footprint of these fixtures I'm using too.
I have two differen types of fixtures. With most of them, I shine each one of the 1150w phantom DE's over a 4'x6' area. I yield at least as much in that 4x6 area than i do/did with 1-1/2 1k watt single endeds(1000w per 4x4)
DE's are for real!
In case you're looking to get into the DE world,
I have quite a few of these fixtures. Again 4'x6' :

And I also have a few of these other phantom types, that are more like gavitas and nanolux.
These ones are a more square footprint. 5'x5' ish: