Ppm questions

Dilan R Wertz

Active Member
Hi guys this is my first grow and I would like for someone to explain to me how to tell how much my plant is eating by testing the ppm of my nutrient water and then by testing the water runoff after watering. I just don't quite understand the process and how it works. If someone could explain the process it would be greatly appreciated. Thanks in advance
 

Dr. Who

Well-Known Member
Sorry but it doesn't work that way.....
Testing of any run off, for a direct relationship between anything as far as use of nutrient, or pH of.....is totally inaccurate!

The run off will pick up old residue's. Therefor, you'll fail.
The liquid it's self, forces a swing in media pH. This in turn, effects the run off pH to not reflect the actual media pH.
This is most reflected in soil use...

Sorry.
 

Daveindiego

Well-Known Member
Sorry but it doesn't work that way.....
Testing of any run off, for a direct relationship between anything as far as use of nutrient, or pH of.....is totally inaccurate!

The run off will pick up old residue's. Therefor, you'll fail.
The liquid it's self, forces a swing in media pH. This in turn, effects the run off pH to not reflect the actual media pH.
This is most reflected in soil use...

Sorry.
What?!!

I’m with OP, I need help on understanding what the testing of runoff PPMs is for.
 

Dilan R Wertz

Active Member
What?!!

I’m with OP, I need help on understanding what the testing of runoff PPMs is for.
Yeah I thought I had seen something where they were testing the runoff ppm and it was telling something about how much the plant was eating. I could be wrong though. Like I say it's my first grow.
 

Dr. Who

Well-Known Member
What?!!

I’m with OP, I need help on understanding what the testing of runoff PPMs is for.
NOTHING!
With any true accuracy!
Some folks have found a "relationship" between things to "figure" pH value. It's still not accurate! Not so I or anyone else should truly trust it.

As far as any media goes. Your run off will contain "salt's" and or other residue's, picked up when passing through the media.

This skews the actual ppm reading of the run off to be out of scale to what is being held by the media...

Metering run off? Not effective.
 

Daveindiego

Well-Known Member
NOTHING!
With any true accuracy!
Some folks have found a "relationship" between things to "figure" pH value. It's still not accurate! Not so I or anyone else should truly trust it.

As far as any media goes. Your run off will contain "salt's" and or other residue's, picked up when passing through the media.

This skews the actual ppm reading of the run off to be out of scale to what is being held by the media...

Metering run off? Not effective.
So the measuring of run off serves no value.

I watered the other day, and never before noticed the runoff. I poured out the saucer full of runoff, and wondered
a.) should I measure the PPMs?
b.) should I have always been emptying the runoff. It looked nasty’ish.
 

Lite

Well-Known Member
Listen to your plant, watch the PH. PPM requirements change depending on stage, size, temp, airflow, humidity, strength/illness, root structure, grow medium. etc etc.

Listen to her, give her what she needs without hurting her.
 

Daveindiego

Well-Known Member
Listen to your plant, watch the PH. PPM requirements change depending on stage, size, temp, airflow, humidity, strength/illness, root structure, grow medium. etc etc.

Listen to her, give her what she needs without hurting her.
I’m fucking shit up bad, and getting discouraged now.
 

Daveindiego

Well-Known Member
What you mean bro?
I’m in week 7 with a plant that is totally fried. All the sugar leaves dried up. Barely any fan leaves left. The flower already ‘feels’ and looks dried out.

I’m cluelessness as to where I fucked up. I’ve significantly reduced nutrient levels in attempts to lower PPMs, so I really don’t think it’s an ‘overfeeding’ issue. I think it’s a late flower nutrient issue (House and Garden), and my inability to properly dial it in.
 

Dr. Who

Well-Known Member
So the measuring of run off serves no value.

I watered the other day, and never before noticed the runoff. I poured out the saucer full of runoff, and wondered
a.) should I measure the PPMs?
b.) should I have always been emptying the runoff. It looked nasty’ish.
Empty it is the winning plan!
Nasty is right, and bad ju ju for your plants if it gets back into the soil/media....
 

legalcanada

Well-Known Member
people test their runoff to make sure there isn't nutrient buildups happening, your ppm and PH of runoff should be similar to what you are putting in. if it's much higher you may want to consider flushing it.

that's why coco is good for newer growers. it's hard to overwater, so you can always just water it with 5gallons or more of nutrient solution until what comes out the bottom is what you are putting in the top.
 

Dilan R Wertz

Active Member
people test their runoff to make sure there isn't nutrient buildups happening, your ppm and PH of runoff should be similar to what you are putting in. if it's much higher you may want to consider flushing it.

that's why coco is good for newer growers. it's hard to overwater, so you can always just water it with 5gallons or more of nutrient solution until what comes out the bottom is what you are putting in the top.
That is what I read but couldn't understand. Thanks!
 

Flowki

Well-Known Member
If you feed a lowish ppm with a good npk ratio you won't see any related issues. You don't have to have run off every feeding that way, once you know the prior is good. You use less nutes, water and don't have to empty run off as much. But that's more toward daily or every other day coco. Would be safer to have run off every feeding if you are watering every 3+ days.
 

Buba Blend

Well-Known Member
It’s my ‘4th’ grow, and now I feel like I’m just smart enough to be stupid about what I’m doing.
You're doing well. Being confused on the journey was routine for me.
My position has changed back and forth over the last two years.
Areas where my opinion changed, sometimes more than once in soil.
Flushing, how to deal with fungus gnats, ph of water to be fed, ph of run off, ppm's of run off, how often I water, what nutrients I use. I can't think others right now but I know there are a bunch of other things where my opinion has changed. Sounds to me like you are learning is all.
 

Dilan R Wertz

Active Member
You're doing well. Being confused on the journey was routine for me.
My position has changed back and forth over the last two years.
Areas where my opinion changed, sometimes more than once in soil.
Flushing, how to deal with fungus gnats, ph of water to be fed, ph of run off, ppm's of run off, how often I water, what nutrients I use. I can't think others right now but I know there are a bunch of other things where my opinion has changed. Sounds to me like you are learning is all.
Thanks man. I think I'm running into a calcium issue right now. Just noticed it on a few fan leaves. So Just watered with 7.5 ml of cal mag and some big bloom. Been keeping ph at 6.5 or 6.6. I just put them under my hps yesterday. I had it under 400 mh at about 15 in above tops of plants. And switched to hps yesterday and had it about the same height above them cause I'm about to start flowering once it recovers from the topping I did. Could that cause some leaves to have goldish brown spots on them?

EDIT: Lol didn't realize you directed that towards him. Thought it was too me haha sorry
 
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