What can your runoff tell you?

GrowBigOrGrowHome

GrowBigOrGrowHome

Well-Known Member
Hello,

I'm growing in soil. I've read about some people getting insight as to what is happening with their plants by either testing the pH or ppm of their runoff. Can someone please give some more information about this? I've done a search and looked in the growFAQ, but can't seem to find the info I need.

Does testing your runoff ever give you useful info if you are growing in soil? What is the correct way to test your runoff (after just plain water, after nutes, etc.)?

Thanks in advance for any help.
 
9

9inch bigbud

Well-Known Member
what are you feeding them with? if like me feeding them hydro nutes then you can run clean water through the pot and catch the run off and test how much salt is in the run off and test the ph as well.

catch the run off adjust you next watering with more or less or no feed at all.
 
GrowBigOrGrowHome

GrowBigOrGrowHome

Well-Known Member
I'm using foxfarm nutes. Are those hydro nutes?

Let's say that my tap water has a ppm of 150. So what would it mean if while using water I found that my runoff had ppms of 800? Would that mean that I'm over nuting my plants by 650 ppm? I understand that would be the case if I was in a medium like rockwool. But doesn't the soil give off salts on it's own that would contribute to the ppms of my runoff? How come it isn't recommended that you test the ppm of the runoff while flushing? Wouldn't that be a sure fire way to tell if you've flushed enough?

I guess I need sort of a top down explanation.
 
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9

9inch bigbud

Well-Known Member
GrowBigOrGrowHome said:
I'm using foxfarm nutes. Are those hydro nutes?

Let's say that my tap water has a ppm of 150. So what would it mean if while using water I found that my runoff had ppms of 800? Would that mean that I'm over nuting my plants by 650 ppm? I understand that would be the case if I was in a medium like rockwool. But doesn't the soil give off salts on it's own that would contribute to the ppms of my runoff? How come it isn't recommended that you test the ppm of the runoff while flushing? Wouldn't that be a sure fire way to tell if you've flushed enough?

I guess I need sort of a top down explanation.
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what soil is it? is it compost or garden soil?

let me say what i do.

i buy a bag of soil/compost add 2 cups of soil to 1 cup of vermiculite mix it up i plant my cutting about 2 week old in a 15L pot with the mix above. i only use water for the 1st 2-3 weeks after that i use vitalink nutes at full strength for 1 feed then 1 water 1 feed then 1 water once the plant gets big i go like this 1 feed - 1 feed - 1 water - 1 feed - 1 feed - 1 water. in other words i feed full strength nute 2 feeds and a good flush so that a little bit of plain water runs out the bottom lets say 500ml-1000m then carry on 2 feeds 1 plane water all the way up till the last 10 days i then use plane water.

what ever nute you use read the instructions and you will not go far wrong fox far i have never used but i know its used for weed and you will be o.k using that.

mix your compost 2 soil - 1 perlite your plants will love you for it
my soil grow plants below
 

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GrowBigOrGrowHome

GrowBigOrGrowHome

Well-Known Member
Thanks for the info 9inch. I'm not having any major plant problems at the moment and I follow the foxfarm chart. I appreciate your help, but I'm still looking for some top down conceptual info about this. I want to know about the pH and ppm of your runoff and what it means.

I guess the heart of my question is about what the soil contributes to the runoff. Once soil has been in a grow for awhile, are there any nutes left in it? I'm sure that depends on the mix of the soil. But even if there are no usable nutes left in it, does soil contribute to the salinity of the runoff?

I guess one way to find out would be to flush and then test the runoff of the next few waterings. I'm not in a position to do that right now with my grow, so I was hoping someone with experience and knowledge can help.

It's especially confusing when it comes to pH. I was reading that the pH is going to raise as your water/nutes pass throught he soil. Starting at 6.2 will help insure that the pH will pass through all the useful levels where the roots can utilize all of the nutrients. So what would you learn from pH'ing your runoff? That indeed your pH is rising?
 
GrowBigOrGrowHome

GrowBigOrGrowHome

Well-Known Member
GrowBigOrGrowHome said:
I've done a search and looked in the growFAQ, but can't seem to find the info I need.
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stickycrippler said:
Did you look good in the growfaq.
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Did you read my first post? :) Heh. I'm just kidding man. I appreciate the help and I'm not trying to give you a hard time.

I will look again, but if you can help me out with a link or anything, that would really, um, help me out.
 
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Florida Girl

Florida Girl

Well-Known Member
GrowBigOrGrowHome said:
Let's say that my tap water has a ppm of 150. So what would it mean if while using water I found that my runoff had ppms of 800? Would that mean that I'm over nuting my plants by 650 ppm? I understand that would be the case if I was in a medium like rockwool. But doesn't the soil give off salts on it's own that would contribute to the ppms of my runoff? How come it isn't recommended that you test the ppm of the runoff while flushing? Wouldn't that be a sure fire way to tell if you've flushed enough?

I guess I need sort of a top down explanation.
Click to expand...


Taking a reading of the runoff will let you know if you have a salt build-up. If your tap water has a PPM of 150 and you add nutes to the water to bring the PPM up to 800 then water your plants... collect some runoff and check the PPM. The number will be somewhat higher then the 800 PPM... that is to be expected... so if your runoff were say 900 I would think that normal.... HOWEVER... if the runoff were say 1200 then I'd think that is an indication of salt building up and the plants need to be flushed.

Make sense?

 
GrowBigOrGrowHome

GrowBigOrGrowHome

Well-Known Member
Florida Girl said:
Taking a reading of the runoff will let you know if you have a salt build-up. If your tap water has a PPM of 150 and you add nutes to the water to bring the PPM up to 800 then water your plants... collect some runoff and check the PPM. The number will be somewhat higher then the 800 PPM... that is to be expected... so if your runoff were say 900 I would think that normal.... HOWEVER... if the runoff were say 1200 then I'd think that is an indication of salt building up and the plants need to be flushed.

Make sense?
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Thanks for the help FloridaGirl! I think I understand what you are saying, but it still leaves me with some questions. So you're saying if I put in 800, I should get back a ppm that is slightly higher (let's say by about 10%) and that is ok.

This should also work with just plain water, right? I read a forum post where they advised to let the plant dry out first and test with just water, but he didn't really elaborate on what the results meant or what you should do to react to the results.

If I get something higher than 10% (or whatever that number is) then it's indicative of too much nutes in the soil, or to put it another way, too many nutes are building up in the soil and I'm heading towards burning my plants. Is that correct?

If so, wouldn't that mean that you can give your plants the same amount of nutes everytime and at some point you could hit a critical level of salts in your soil and burn the plant (even though you've been feeding a the exact same amount everytime?) Does that really happen?

Just to make sure, you're saying that in order to react to a high runoff, I should flush (even if I don't see any indications of burn yet on the plants.) I also assume that in the future, I should give the plants lower ppms of nutes when I feed.

Do you know where the normal increase (the 10%) comes from?

And what about pH?
 
Dirtyboy

Dirtyboy

Well-Known Member
Ya want to water (ph of 7) the plant slowly so that the water is soaking into the soil and not running down the sides. The very first few drops are collected and then ya can check the soils ph.
 
GrowBigOrGrowHome

GrowBigOrGrowHome

Well-Known Member
Dirtyboy said:
Ya want to water (ph of 7) the plant slowly so that the water is soaking into the soil and not running down the sides. The very first few drops are collected and then ya can check the soils ph.
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Thanks Dirtyboy.

So the purpose of testing the pH of your runoff is that it tells you the pH of your soil?
 
Florida Girl

Florida Girl

Well-Known Member
GrowBigOrGrowHome said:
If I get something higher than 10% (or whatever that number is) then it's indicative of too much nutes in the soil, or to put it another way, too many nutes are building up in the soil and I'm heading towards burning my plants. Is that correct?

If so, wouldn't that mean that you can give your plants the same amount of nutes everytime and at some point you could hit a critical level of salts in your soil and burn the plant (even though you've been feeding a the exact same amount everytime?) Does that really happen?

Just to make sure, you're saying that in order to react to a high runoff, I should flush (even if I don't see any indications of burn yet on the plants.) I also assume that in the future, I should give the plants lower ppms of nutes when I feed.

Do you know where the normal increase (the 10%) comes from?

And what about pH?
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Runoff with a much higher PPM out then in is an indication of salt buildup. I've read that it's a good idea to flush plants every 2 or 3 weeks.... no matter what. I'm not growing in soil... but I am flushing every 2 weeks. See here's the thing.... by the time you see a problem in the plant/leaves.... it's already done damage. So it's best to be proactive and carefully monitor your PH and PPM and flush every 2 or 3 weeks as a safety to prevent the buildups.

I'm a new grower myself.... my first problem was PH... got that under control... my second problem was PPM... got that under control now too. I will say this... my plants would be dead if I hadn't bought my meter.

I'm loving everything I'm learning.... but I had no idea when I started that growing a WEED could be so challenging :mrgreen:

 
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Florida Girl

Florida Girl

Well-Known Member
Dirtyboy said:
Correct......... I have not tested my ppm. I always looked at that as a hydro thing.
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That could very well be true... I'm not growing in soil. However... I would think even with soil you would want to monitor the PPM when you feed the plants nutes to make sure you don't give them too much.... no????

 
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Dirtyboy

Dirtyboy

Well-Known Member
Ya could........ i suppose. No one does it that i have heard. Hydro its a must. Good thinkin girl.
 
9

9inch bigbud

Well-Known Member
remember this!

"what most growers call food i.e> nuterants is not the plants food! it only helps the plant to grow! the real food is the light you give it."

there is no need to keep your plant pumped up with nutes and all this additive crap! do not worry what is in the ground worry about what is above ground that is what will tell you what you need to do.


no mater what you put in the soil it will not make it grow as faster" when you have maximum light then worry about the soil.

follow the manufactures instructions and flush every other watering for top results, because pumping it with shit will most likely kill it. if the plant looks green and healthy you are doing all that it asks.
 
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GrowBigOrGrowHome

GrowBigOrGrowHome

Well-Known Member
Florida Girl said:
That could very well be true... I'm not growing in soil. However... I would think even with soil you would want to monitor the PPM when you feed the plants nutes to make sure you don't give them too much.... no????
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That makes a heap of sense to me too Florida. I guess what I'm trying to figure out though, is whether or not the soil contributes salt content to the runoff that aren't nutrients, excess or otherwise. Soil is kind of a soup of chemicals waiting to break down when wet. Does soil give off saline that appears in your runoff that isn't usable nutrients for the plant?

9inch bigbud said:
remember this!

"what most growers call food i.e> nuterants is not the plants food! it only helps the plant to grow! the real food is the light you give it."

there is no need to keep your plant pumped up with nutes and all this additive crap! do not worry what is in the ground worry about what is above ground that is what will tell you what you need to do.
Click to expand...
So you are saying that there is NO benefit or NOTHING to be learned from testing your runoff? Why would having more information be a bad thing? Are you also saying that all things being equal, two clones from the same plant, one on nutrients, one on water will produce the same amount of bud? Have you ever tried this?

9inch bigbud said:
follow the manufacturers guides and add 1 cup of perlite to 2 cups of soil. after every 2nd feed just use plane water.
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Listen, again I appreciate your help, but this is very similar to what you said previously about following the directions on the package. I'm trying to UNDERSTAND what is going on, not just mindlessly read a chart and hope for the best. I'm trying to actually learn something.

Florida Girl said:
Runoff with a much higher PPM out then in is an indication of salt buildup. I've read that it's a good idea to flush plants every 2 or 3 weeks.... no matter what. I'm not growing in soil... but I am flushing every 2 weeks. See here's the thing.... by the time you see a problem in the plant/leaves.... it's already done damage. So it's best to be proactive and carefully monitor your PH and PPM and flush every 2 or 3 weeks as a safety to prevent the buildups.

I'm a new grower myself.... my first problem was PH... got that under control... my second problem was PPM... got that under control now too. I will say this... my plants would be dead if I hadn't bought my meter.

I'm loving everything I'm learning.... but I had no idea when I started that growing a WEED could be so challenging :mrgreen:
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yeah, I had the exact same experience, not knowing my pH and I got nute lock up. I didn't know the ppm of my nutes and I burned my plants. It's crazy how you have to make these mistakes for yourself in order to figure it out sometimes.

Testing the ppm of your runoff makes a ton of sense to me if you are growing hydroponically. It seems clean and you know where those salts are coming from. It seems like the same thing should be applied to soil grows. I just wonder what kinda wrench the soil monkey throws into the mix. When I'm done with my current grow, I will take some soil from the pot and flush it. Then I can test and find out if there are any salts that the soil produces on it's own. It's a simple enough thing to figure out. I was just hoping that someone already had the info so I wouldn't have to go through the trouble.
 
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9

9inch bigbud

Well-Known Member
GrowBigOrGrowHome said:
That makes a heap of sense to me too Florida. I guess what I'm trying to figure out though, is whether or not the soil contributes salt content to the runoff that aren't nutrients, excess or otherwise. Soil is kind of a soup of chemicals waiting to break down when wet. Does soil give off saline that appears in your runoff that isn't usable nutrients for the plant?



So you are saying that there is NO benefit or NOTHING to be learned from testing your runoff? Why would having more information be a bad thing? Are you also saying that all things being equal, two clones from the same plant, one on nutrients, one on water will produce the same amount of bud? Have you ever tried this?



Listen, again I appreciate your help, but this is very similar to what you said previously about following the directions on the package. I'm trying to UNDERSTAND what is going on, not just mindlessly read a chart and hope for the best. I'm trying to actually learn something.



yeah, I had the exact same experience, not knowing my pH and I got nute lock up. I didn't know the ppm of my nutes and I burned my plants. It's crazy how you have to make these mistakes for yourself in order to figure it out sometimes.

Testing the ppm of your runoff makes a ton of sense to me if you are growing hydroponically. It seems clean and you know where those salts are coming from. It seems like the same thing should be applied to soil grows. I just wonder what kinda wrench the soil monkey throws into the mix. When I'm done with my current grow, I will take some soil from the pot and flush it. Then I can test and find out if there are any salts that the soil produces on it's own. It's a simple enough thing to figure out. I was just hoping that someone already had the info so I wouldn't have to go through the trouble.
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all the testing as been done for you! dont try to reinvent the wheel it already been done! and it works

i give sound advice and have grown for 15+ years successfully if you cant learn something that is probbilly the best advice in this thread then carry on my friend. i grow in soil with results that hydro grower wish they could achieve.

i can see you dont need 15 years expertise in growing weed so i bid you fear well.

my ph is out
i have leaf burn
nute lock out etc
carry on
 
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Florida Girl

Florida Girl

Well-Known Member
GrowBigOrGrowHome said:
I guess what I'm trying to figure out though, is whether or not the soil contributes salt content to the runoff that aren't nutrients, excess or otherwise. Soil is kind of a soup of chemicals waiting to break down when wet. Does soil give off saline that appears in your runoff that isn't usable nutrients for the plant?
Click to expand...

ok... I got out my book and read the chapter on SOIL.... it talks about soil and the importance of purchasing a good quality soil... it also talks about how a lot of these soils have nutrients already added so the plants don't need any added nutes in the first 3 weeks. So... if the soil has nutrients in it already then I'd say YES... that soil is contributing salt content to the runoff.

Now if you are not using purchased soil.... just soil from your backyard then I'd guess there are salts in it as well.... although added by mother nature instead of man.

It sounds to me like your real question is .. Is there salt in soil? I think the answer is "yes"... but how it gets there and at what rate really depends on a number of factors.

Lastly, the chapter really focused on the PH level of the soil so if you've got that under control then you are likely doing fine. In terms of nute/salt build up it recommended flushing once a month for soil.

The book I have is the medical growers bible by jorge cervantes. I really like the book... pretty good information for us noobs.

:peace:
 
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