Hydro Specificity

[MootPointBlank]

This is a question originally posed to Hick, who, being a soil farmer, recommended that I post it here for accuracy and the enlightenment of all.

Hello Hick,
I was reading the sticky on nutrient requirements and I was wondering, when it states that TDS should be from 800-3000 ppm, what conversion factor is used? Right now, my meter is set to .5 and even when mixing nutes to spec I'm only getting values around 25% of the minimum listed. I'm using de-ionized water that EC's to 0 before mixing, so are we accounting for water that already has a fairly predominant mineral level, as well? From what I've read, it seems that an overall lower TDS is less stressful to the roots, though, I find it difficult to tell one way or the other because so much of the data conflicts. Do I shoot for 800ppm anyway? Would it be easier if everyone started using EC with stated units?
This is for my veg res where I'll be vegging clones into sexual maturity before moving to the flower res.

Thanks,
MPB

 

[MootPointBlank]

By the way, here's the link to that nutrient requirements doc I mentioned.

 

[Hick]

By the way, here's the link to that nutrient requirements doc I mentioned.

The above text is excerpted from George Van Pattens' excellent book "Gardening: The Rockwool Book".

I can't answer your question moot', but I will "bump" it for you...

 

[Shockeclipse]

I am about to do a res change heee in the nest couple days, I had something going on with my plant before this lawt change so I had them on real low nutes like 250ppms. They are bouncing back, and I am going to probably bring the nutes up around 500 and see how they respond. I am thinking that would be your best bet. Try one level and then up it until you feel comfortable. I fear the nutes so I am trying to stay on the low side.

 

[MootPointBlank]

I am about to do a res change heee in the nest couple days, I had something going on with my plant before this lawt change so I had them on real low nutes like 250ppms. They are bouncing back, and I am going to probably bring the nutes up around 500 and see how they respond. I am thinking that would be your best bet. Try one level and then up it until you feel comfortable. I fear the nutes so I am trying to stay on the low side.

Thanks Shock,
What is the conversion factor you're using? Will your meter give you EC and is it in millisiemens(mS) or microsiemens(uS)? The crux of my inquiry lies in having a level playing field. If you already know this, then you understand why I'm asking. PPM is a calculation based off of EC, without knowing the conversion factor used in the calculation, PPM can fluctuate drastically. For instance, your 250ppm could be 179ppm to me depending on what conversion factor is used.

MPB

 

[Shockeclipse]

Thanks Shock,
What is the conversion factor you're using? Will your meter give you EC and is it in millisiemens(mS) or microsiemens(uS)? The crux of my inquiry lies in having a level playing field. If you already know this, then you understand why I'm asking. PPM is a calculation based off of EC, without knowing the conversion factor used in the calculation, PPM can fluctuate drastically. For instance, your 250ppm could be 179ppm to me depending on what conversion factor is used.

MPB

.50..................microsiemens(uS)