Can someone help me out with ppm and let me know if I've got this figured out right

Say they recommend 1000ppm for flower. I'm thinking 1000pm of what? I'm using 3 different nutes sometimes. What's the ratio? I learned that you basically follow the ratios of whatever the nutrients say. If I'm feeding 15ml grow big and 6 tiger bloom and I finally test the ppm and it shows up to be 700 then I know I can use more following the same ratio to get to 1000. I don't really understand why that 1000ppm number is better than what the nutrient company suggests? Why wouldn't they just suggest however much it takes to get to 1000ppm? I should say I've only used ff nutrients and just followed their schedule through my first grow. Never tested ppm. Just bought the meter today. I don't necessarily understand the run off portion of ppm testing. The guy says when his ppm is below 800 he starts feeding then. Bc he uses pre fert soil. Same as me. So should my ppm always be above 800 when I test the run off? What does knowing the ppm of the water before you feed and the ppm of the run off tell me? I think I understand checking the run off to see whether they need fed. Like say next week I water with no feed and check the ppm and see that it's above 800 I'm good. But the next time I water is down to 400, I'll know I need to feed next watering. But I guess I don't know how much to feed at that point, to bring it back up to 800ppm. At that point would I feed next watering and then check the run off to make sure it's higher than 800. Guys if you read through all this I really appreciate it.

One of the reasons for testing your ppms is to guage whether the plant is actually eating or not. If I suspect a lockout for example, I'll test my ppms runoff compared to what I fed, if the ppms are significantly lower, the plant is still hungry, if it's significantly higher, the plant isn't eating, hence there's a lockout happening, lockout meaning something is preventing nutrient uptake. If I don't suspect a lockout, testing ppms is useless in my opinion, but I can't speak for everyone. I too use the trio, and I don't feed based on ppms, I also don't follow FF feeding chart either as it tends to burn your plants. Let the plants be your guide, not some numbers that doesn't necessarily pertain to your garden. Good luck and happy growing.

You don't test runoff of soil. EC is a better measurement than PPM, because there are multiple PPM scales.

I've never really gone by runoff ppm as I water so there is no runoff. I generally feed with about 600ppm every 2nd watering depending on strain. Using RO water I don't have to worry about mineral buildup from hard water and feed low enough that I don't need to get runoff to discard. I do have low RH most of the time so you want to feed less when lower and more when higher. If the plants want more they'll let me know and I'd rather have to add more than try to get rid of too much.

PJ Diaz said:

You don't test runoff of soil. EC is a better measurement than PPM, because there are multiple PPM scales.

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Here you go. Now you can figure it out. Sized for printing.

Ec is a one and only universal measurement, when you say ppm idk what scale you're talking about. 1000ppm could be 2.0 but idk which scale you're working with.

Dontjudgeme said:

One of the reasons for testing your ppms is to guage whether the plant is actually eating or not. If I suspect a lockout for example, I'll test my ppms runoff compared to what I fed, if the ppms are significantly lower, the plant is still hungry, if it's significantly higher, the plant isn't eating, hence there's a lockout happening, lockout meaning something is preventing nutrient uptake. If I don't suspect a lockout, testing ppms is useless in my opinion, but I can't speak for everyone. I too use the trio, and I don't feed based on ppms, I also don't follow FF feeding chart either as it tends to burn your plants. Let the plants be your guide, not some numbers that doesn't necessarily pertain to your garden. Good luck and happy growing.

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This is very helpful, thank you.

Star Dog said:

Ec is a one and only universal measurement, when you say ppm idk what scale you're talking about. 1000ppm could be 2.0 but idk which scale you're working with.

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That makes sense. EC is just another measurement, but a universal one. I had read there were other ppm scales but never gave it another thought. Thanks

OldMedUser said:

Here you go. Now you can figure it out. Sized for printing.

View attachment 5159635

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Thank you

Dontjudgeme said:

One of the reasons for testing your ppms is to guage whether the plant is actually eating or not. If I suspect a lockout for example, I'll test my ppms runoff compared to what I fed, if the ppms are significantly lower, the plant is still hungry, if it's significantly higher, the plant isn't eating, hence there's a lockout happening, lockout meaning something is preventing nutrient uptake. If I don't suspect a lockout, testing ppms is useless in my opinion, but I can't speak for everyone. I too use the trio, and I don't feed based on ppms, I also don't follow FF feeding chart either as it tends to burn your plants. Let the plants be your guide, not some numbers that doesn't necessarily pertain to your garden. Good luck and happy growing.

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Is it the run off of the actual feed water itself that you can test like that? Or the next waterings run off? For instance say I've got my feed water all mixed up at 800ppm or ec whichever I end up using, I water with it, then check the run off? It will immediately either take in these nutrients if it's hungry or discard them if there's a lock out? Showing in that run off water which is which. The reason I ask is bc I wouldn't think that would be the case. I wouldn't think the roots could immediately either use or discard that quickly. Iwould think it would take a few days to either use them or not use them. Then when you water a couple days later you'd check that run off to see if the plant are anything these past couple days. I don't know about these things, so it's just ignorance, but I'm wanting to understand. Thanks bro

OldMedUser said:

I've never really gone by runoff ppm as I water so there is no runoff. I generally feed with about 600ppm every 2nd watering depending on strain. Using RO water I don't have to worry about mineral buildup from hard water and feed low enough that I don't need to get runoff to discard. I do have low RH most of the time so you want to feed less when lower and more when higher. If the plants want more they'll let me know and I'd rather have to add more than try to get rid of too much.

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Bc when you have lower rh water flows through the plant more right? Meaning it would be taking more nutrients through the plant, hence you'd want to feed less.

ClaytonNewbilFontaine said:

Bc when you have lower rh water flows through the plant more right? Meaning it would be taking more nutrients through the plant, hence you'd want to feed less.

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Plants can take up water and/or nutrient so yes you're on the right track, idk exactly how it works but hot dry air increases transpiration raising the ec making nutrient more concentrated due to water loss.

Star Dog said:

Plants can take up water and/or nutrient so yes you're on the right track, idk exactly how it works but hot dry air increases transpiration raising the ec making nutrient more concentrated due to water loss.

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I appreciate your patience in teaching. I just wanna know I understand things correctly. I'll take one line from someone's reply and it'll send me on a 2 day tangent trying to learn what the guy was talking about.

ClaytonNewbilFontaine said:

Is it the run off of the actual feed water itself that you can test like that? Or the next waterings run off? For instance say I've got my feed water all mixed up at 800ppm or ec whichever I end up using, I water with it, then check the run off? It will immediately either take in these nutrients if it's hungry or discard them if there's a lock out? Showing in that run off water which is which. The reason I ask is bc I wouldn't think that would be the case. I wouldn't think the roots could immediately either use or discard that quickly. Iwould think it would take a few days to either use them or not use them. Then when you water a couple days later you'd check that run off to see if the plant are anything these past couple days. I don't know about these things, so it's just ignorance, but I'm wanting to understand. Thanks bro

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Maybe I should have clarified this a bit more because I had a feeling you would ask this question. You are right in thinking that you can't test the ppm immediately after feeding. You do in fact have to wait until the next feeding to guage the ppm. While nutrient availability in liquid form is immediate, it's not immediate enough for you test right away.

Dontjudgeme said:

One of the reasons for testing your ppms is to guage whether the plant is actually eating or not. If I suspect a lockout for example, I'll test my ppms runoff compared to what I fed, if the ppms are significantly lower, the plant is still hungry, if it's significantly higher, the plant isn't eating, hence there's a lockout happening, lockout meaning something is preventing nutrient uptake. If I don't suspect a lockout, testing ppms is useless in my opinion, but I can't speak for everyone. I too use the trio, and I don't feed based on ppms, I also don't follow FF feeding chart either as it tends to burn your plants. Let the plants be your guide, not some numbers that doesn't necessarily pertain to your garden. Good luck and happy growing.

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How does runoff ppm tell you anything? You can run water through straight peat and it will raise the EC. All runoff tells you is that something washed out. It doesn't tell you what.

xtsho said:

How does runoff ppm tell you anything? You can run water through straight peat and it will raise the EC. All runoff tells you is that something washed out. It doesn't tell you what.

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Agreed. From what I understood, the OP was asking what is the purpose behind PPM gauging. My response was predicated on that question. If I understood him incorrectly, my apologies.

Dontjudgeme said:

Maybe I should have clarified this a bit more because I had a feeling you would ask this question. You are right in thinking that you can't test the ppm immediately after feeding. You do in fact have to wait until the next feeding to guage the ppm. While nutrient availability in liquid form is immediate, it's not immediate enough for you test right away.

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Yes, thank you. I've been thinking about this since yesterday. I just couldn't imagine it would tell me anything that fast. I think I understand everything. I'm still going to feed how I've been but I'll start checking the run off to see if what's going on with her. I appreciate all the help.

ClaytonNewbilFontaine said:

Bc when you have lower rh water flows through the plant more right? Meaning it would be taking more nutrients through the plant, hence you'd want to feed less.

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Yeppers. For the longest time I was getting toxic salts buildup that would show up about midway thru flower until I clued into having RH of 30% or less was the cause so cut my ppm in half doing DWC and the problem went away. The same thing will happen in any method if the nutrient levels are too high while the RH is low.

I usually used AN 3-part at half strength then went up or down from there depending on how the plants reacted. Half is 2ml/L which I fed every 2nd watering in pots. That worked out to 300ppm.

OldMedUser said:

Yeppers. For the longest time I was getting toxic salts buildup that would show up about midway thru flower until I clued into having RH of 30% or less was the cause so cut my ppm in half doing DWC and the problem went away. The same thing will happen in any method if the nutrient levels are too high while the RH is low.

I usually used AN 3-part at half strength then went up or down from there depending on how the plants reacted. Half is 2ml/L which I fed every 2nd watering in pots. That worked out to 300ppm.

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God damn I bet that felt good to figure out! Great piece of info for me, as I tried to get my rh as low as possible during my first grow bc I was so damn scared of mold. For no real reason, but bc it exists. Also I ran my temps low, bc I thought I was supposed to keep them in the mid to low 70's. So to achieve a good vpd I had to have my rh low. But I could never get it below 46%. Usually ran in the low 50's. But what you wrote is really good info to have. How did the salt buildup show in the plant? The fabric pot I used last grow is coated in what I think is salt. Though it didn't taste salty when I tested it. I don't know if that tells me anything though, or if it's normal. Recently I've been hearing that my temps should be in the lower 80's with rh around 60% through most of the grow, up into late flower when the buds are packing on more weight. At that point drop the temps a bit and lower rh into the mid 40's. It's info from a person who's helped me a lot, who knows some things. But that doesn't mean I don't want to verify the info. From what I've read it seems like good advice. And it would be easier during summer to keep it at 80/60% than what I had been going for. Was it bc of the rh where you live that your rh was so low? Also what showed in the plant that let you know it was tox salt build up. You think all the white dust coating my old fabric pot has to be salts, right? Does that show or tell me anything? I was watering until run off every time. I figured I'd put all the questions I asked at the end so you don't have to go through to see them again. If you answer any of them, I mean. No worries either way. Thanks for the reply and the info.

6:30am and I haven't got to bed yet. Started painting the grow room and it took longer than I thought. Still some strips showing through after 6 coats and it will need a couple more but I'm bushed.

Toxic salts buildup, TSB, happens over a long period of too much nutes. Not enough to show nute burn but enough to slowly build up in the plant tissues until the salts just start burning out the leaves mid-flower and progresses right into the sugar leaves by the end. You expect soft yellow leaves near the finish but these go yellow/red/brown all across the leaf surface and they get thick and crispy. Usually starts in the old, lower fan leaves but if there's a lot of radiant heat from lights it can start up top as they pull more water with nutes trying to stay cool. Once I kept my ppm down to around 5 - 600 the plants were happy and didn't get TSB. I'm in northern Alberta and even now with recent rain then warm days the RH in my mancave is only 44% @75F. When it's -25 outside the RH can be as low as 10% and maybe 25% in the grow room.

80F/60% is great for plants and shouldn't cause mold in buds with lots of air circulation. Don't need to worry about that until the last 3 weeks or so when the colas are fat and dense. Rest of flowering can be higher no problem and probably better for the plants and yields. I aim for 75 but 80 is fine. My basement stays cool as it's underground and has ice cold clay all around it. I pull the air for my room from the basement and it's only 61F down there now.

I don't use fabric bags so not sure if it's salts or fungi on yours but I would suspect salts. I don't think they taste like table salt so if salts they should soak out if you put them in the bathtub and fill it with warm water to leave overnight. Add a good shot of bleach and maybe a bit of Tide too.