Relationship between PPM in and PPM out

Hi everyone, I'm just finishing out my second grow in a long time and have one plant remaining, a small Amnesia Haze that I experimented with starting 12/12 from seed (I had extra room for a small plant in my room that just switched 12/12 for three larger plants).

This is my first grow using a ppm meter and I only started using half way through. My question is this, as the title states, what's the relationship between ppm in and out?

This AH is in a one gallon fabric pot with FFOF, perlite, and clay balls. It gets watered roughly every 3 days. 6 days ago I watered it with 10ml per gallon of my grow nutes which gave a ppm in of 940. The ppm out was 1500. (ph in and out was 6.4 for this feeding). The previous ppm out, 3 days earlier was 1170 for a net reduction of 610 ppm.

Three days later I watered with rested water only, which is 200 ppm in, and the ppm out was 1150, for a net reduction of 550. (ph 6.4 in and 6.5 out). I'm about to water tonight...

My question is this, given that I'm about 3 weeks from harvest and want max 1600ish ppm?? for mature flower, what should I mix my ppm nutes at today? Each feeding seems to "eat" 550ish ppm, so do I mix to 1000 ppm in so after the plant uses roughly 550, I'm left with 1600 out? Does this math even make sense?

And when the charts say a mature flower ppm range to target is 1100 - 1600 ppm, does that mean to hit that target for your mixed feeding going in? Or out?

I hope this post isn't too confusing... but I'm confused a bit.

Is this a boring topic or are others just as confused as me? I thought someone would have some input.

I ended up watering last night with 800 ppm water in, and got 1650 ppm out (net reduction of 300 ppm).

it not that its boring, its just that this is really a hydro thing, no one keeps track of it in soil, or even coco or promix. you feed what you feed, the plant uses what it needs, and the excess gets washed out the next time you water. as long as you're getting a little run off when you water, it should never be an issue

Runoff is shit hard to fathom unless your in hydro and then even single nutrient testers are needed for the whole story.

Maybe those extra ppms in your runoff were anions or a ph change releasing cations or you had salt build up or youve exceeded your calcium cation exchange and the rest is leaching.

Im not versed enough to get into it yet, easier to ignore runoff and read plants which is what a lot of us do combined with a good well trialed fert schedule.

Fox farm contains nutrients. If you pour water through it the water will increase in ppm/ec as it passes through.

The nutrient charts are suggesting a ppm/ec of what to put in.

For me in coco if I were getting those reading ( I wouldn't be checking if I didn't have a problem) then I would have salt build up and a nutrient lock out.

If you're still 3 weeks out I'd give it some veg nutes. Looks like you have a bad Nitrogen deficiency....and where did all your leaves go?? Dropped off from lack of N or did u defoliate? Your leaves shouldn't be that yellow unless you've been flushing the final week. I'm sure people here will state other opinions but I like to keep my plants green until harvest flush time.

Buds look good BTW. Didn't mean to seem all negative.

If i had to guess its cause you have soil that has nutes and ppms in it

And your adding nutrients

If you leech the medium as in run some plain water through it should decrease.



Im not a dirt guy though but i grew in coco for years. And in my oppinon it SHOULD be treated like hydroponics just a differnt kind.

Cause salt build up in coco promix and rock wool are real things lol

Edit just realized couple peeps already said this haha

Excellent, thanks for all the input. I didn't realize ppm was more of a hydro thing but I get that deciphering what the ppm out contains would be difficult. I'll pay less attention to ppm out and try to read the plants more.

As for missing leaves, yellowing, and potential lack of Nitrogen... this could all be the case. I actually screwed this plant up early in its life with way wrong ph water (I got a ph meter and ppm meter half way through this grow). For the first month or so, I was watering with ph 8.0 water and didn't realize it. I'm not sure if I caused some lockout early and that is why the yellowing and lost leaves now? I'm happy with the buds but don't like the leaves... although I would imagine I did some early damage. I'll get my ph right from the start on the next grow.

There may not even be 3 weeks left... many trichomes are milky, some amber, but still many clear as well. I may harvest a bit early because of the damaged leaves.

Thanks again for the help with the ppm thing... I feel I understand it a bit better now.

troutfarm said:

Excellent, thanks for all the input. I didn't realize ppm was more of a hydro thing but I get that deciphering what the ppm out contains would be difficult. I'll pay less attention to ppm out and try to read the plants more.

As for missing leaves, yellowing, and potential lack of Nitrogen... this could all be the case. I actually screwed this plant up early in its life with way wrong ph water (I got a ph meter and ppm meter half way through this grow). For the first month or so, I was watering with ph 8.0 water and didn't realize it. I'm not sure if I caused some lockout early and that is why the yellowing and lost leaves now? I'm happy with the buds but don't like the leaves... although I would imagine I did some early damage. I'll get my ph right from the start on the next grow.

There may not even be 3 weeks left... many trichomes are milky, some amber, but still many clear as well. I may harvest a bit early because of the damaged leaves.

Thanks again for the help with the ppm thing... I feel I understand it a bit better now.

Click to expand...

Glad to see your questions got answered. Going forward if you decide to continue using FFOF, try watering with plain (properly PH'd) water for the first couple weeks. FFOF is already saturated with lots of goodies and nutrients, plenty to keep the plant thriving through veg.

smokebros said:

Glad to see your questions got answered. Going forward if you decide to continue using FFOF, try watering with plain (properly PH'd) water for the first couple weeks. FFOF is already saturated with lots of goodies and nutrients, plenty to keep the plant thriving through veg.

Click to expand...

Thanks for the info smokebros, I actually didn't add any nutes for the first month or so as I was aware that FFOF was loaded... but my ph 8.0 water may have caused some uptake issues in those first vital weeks? Silly mistake as I read over and over that ph is everything. Also, this was a weird plant because I started it from seed 12/12 (as mentioned earlier, I had extra space in my 12/12 room so I was experimenting). I started running bloom nutes once I noticed flowering but I probably should have kept up with the Nitrogen a bit. Lesson learned and this will all go in the knowledge vault for next grow.

Thanks again everyone!

Ph is a fucking meaningless log. number to me...

Kingrow1 said:

Ph is a fucking meaningless log. number to me...

Click to expand...

I don't understand.

troutfarm said:

I don't understand.

Click to expand...

I believe @Kingrow1 does more of an organic style of growing with healthy microbial life in the soil. Since the microbes do a lot of the work in breaking down the nutrients it makes it easier for the plant to uptake nutrients. And since the microbes allow the food to become more available, the plant can use what it needs regardless of what PH the water is.
I could be wrong but I believe that's what he's referring to. Either that, or he must amend the soil before hand like a real farmer does.

troutfarm said:

Thanks for the info smokebros, I actually didn't add any nutes for the first month or so as I was aware that FFOF was loaded... but my ph 8.0 water may have caused some uptake issues in those first vital weeks? Silly mistake as I read over and over that ph is everything. Also, this was a weird plant because I started it from seed 12/12 (as mentioned earlier, I had extra space in my 12/12 room so I was experimenting). I started running bloom nutes once I noticed flowering but I probably should have kept up with the Nitrogen a bit. Lesson learned and this will all go in the knowledge vault for next grow.

Thanks again everyone!

Click to expand...

You should stop feeding now, because what your reading is the buildup of the nutes already in the roots/soil, and with 2 weeks left, I would just water with 6.3 water.
The yellowing could have been caused by a MG/N def (did you use Calmag?)
Yea, PPM is really a hydro thing, but in a good soil I wouldn't go above 900 when feeding your plants.
At 8 weeks of 1600 ppm in soil, your salt buildup must be huge (wacky PH?)
Nice plant by the way (next time keep the leaves )

troutfarm said:

Excellent, thanks for all the input. I didn't realize ppm was more of a hydro thing but I get that deciphering what the ppm out contains would be difficult. I'll pay less attention to ppm out and try to read the plants more.

As for missing leaves, yellowing, and potential lack of Nitrogen... this could all be the case. I actually screwed this plant up early in its life with way wrong ph water (I got a ph meter and ppm meter half way through this grow). For the first month or so, I was watering with ph 8.0 water and didn't realize it. I'm not sure if I caused some lockout early and that is why the yellowing and lost leaves now? I'm happy with the buds but don't like the leaves... although I would imagine I did some early damage. I'll get my ph right from the start on the next grow.

There may not even be 3 weeks left... many trichomes are milky, some amber, but still many clear as well. I may harvest a bit early because of the damaged leaves.

Thanks again for the help with the ppm thing... I feel I understand it a bit better now.

Click to expand...

Jimdamick said:

You should stop feeding now, because what your reading is the buildup of the nutes already in the roots/soil, and with 2 weeks left, I would just water with 6.3 water.
The yellowing could have been caused by a MG/N def (did you use Calmag?)
Yea, PPM is really a hydro thing, but in a good soil I wouldn't go above 900 when feeding your plants.
At 8 weeks of 1600 ppm in soil, your salt buildup must be huge (wacky PH?)
Nice plant by the way (next time keep the leaves )

Click to expand...

Leaves fell off early from pH? Maybe.

Yellowing from low N? Possible from improper pH ranging of solution but I might say it's combined with high P use also....

You never listed what you use
How much
in-going pH levels

If you bother TO list what you use...List everything you use, and how much of each please...

Nice in the end though!

I only use ec to measure waste myself.
Ec is the only accurate measurement for soil too really.
You mix a sample with distilled water. Waste for soil isn't accurate.

smokebros said:

I believe @Kingrow1 does more of an organic style of growing with healthy microbial life in the soil. Since the microbes do a lot of the work in breaking down the nutrients it makes it easier for the plant to uptake nutrients. And since the microbes allow the food to become more available, the plant can use what it needs regardless of what PH the water is.
I could be wrong but I believe that's what he's referring to. Either that, or he must amend the soil before hand like a real farmer does.

Click to expand...

Ph does not show alkalinity and stuff .

Jimdamick said:

You should stop feeding now, because what your reading is the buildup of the nutes already in the roots/soil, and with 2 weeks left, I would just water with 6.3 water.
The yellowing could have been caused by a MG/N def (did you use Calmag?)
Yea, PPM is really a hydro thing, but in a good soil I wouldn't go above 900 when feeding your plants.
At 8 weeks of 1600 ppm in soil, your salt buildup must be huge (wacky PH?)
Nice plant by the way (next time keep the leaves )

Click to expand...

Awesome, thanks... max 900 in is good info. Yes, I did add some Calmag on a couple occasions, about 5ml per gallon which was the bottle recommended mix. I didn't trim the leaves, many yellowed and fell off but I think that may have been accelerated by my poor ph'd water for the first month or so (8.0+ ph), and Nitrogen shortage.

Dr. Who said:

Leaves fell off early from pH? Maybe.

Yellowing from low N? Possible from improper pH ranging of solution but I might say it's combined with high P use also....

You never listed what you use
How much
in-going pH levels

If you bother TO list what you use...List everything you use, and how much of each please...

Nice in the end though!

Click to expand...

I'm hoping most of the plants problems are from my poor first month ph bobble. I won't make that mistake again.

As for feeding specifics... I just let the FFOF do it's thing for the first month, but this is the time I had the 8.0 ph water in. Once I noticed flower, I started my bloom nutes, usually about 5 to 10ml per gallon, which is 1/4 to 1/2 recommended. The problem is I don't know what's in the nutes. It's a home mix from a reputable local grow store. It's come up a few times that is a bad idea, not to know what's in your feed. And, I agree and will stop using this stuff for next grow. But for now, it's from a store with a strong following and says it's "Bloom"... I wish I knew more.

I used Cal/mag and Epsom Salts a couple times each over the past 3 weeks... and switched from water to nute feeding every 3ish days.

ph in AND out has always been between 6.3 and 6.5. But again, I only got my ppm and ph meter a month or so into this grow so I don't have hard numbers from that earlier period.

I will flush for the rest of the grow and harvest early. This was just a fun experiment 12/12 from seed and the buds are more than I expected. I started a Jack Herer at the same time and recently harvested. My previous math of 20% of wet weight shows I'll get 0.6 Ounce from that one. I'm expecting closer to 0.75 to 1.0 Ounce out of this AH. Which is more than I thought when I started these ladies.

Thanks again for all the help. This forum is great!