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 Post subject: ppm rising
PostPosted: Mon Jan 16, 2006 2:34 am 
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Seed

Joined: Sun Jan 15, 2006 11:55 am
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hi guys thanks in advance for all the support...
ok here goes.....

i have a 4'x8' aeroponic unit with a 125litre reservoir.
All is fine, now at week 5 of flower and looking real good.

Concerning ppm's, i have read in a few articles stating that aeroponics prefer a lower ppm of around 700 in veg and 900 in flower.i have looked through the forum and you seem to always suggest to follow the recipe for succes in aero.....
However, in the last mix, i tried the full mix (flower stage2) which says 1500ppm or so...I got the ppm reading at that level for about 115 ltres of solution.After about 3 days the solution was at around 85 litres and the ppm had risen to 1800.

My question is as follows: if I get the ideal nute ratio, shouldn't it stay at the same level, the water and nutes being use at the same proportion? In the first few weeks when i started, i used half the amount and the ppm's were actually going down.
Thanks.


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PostPosted: Mon Jan 16, 2006 7:06 am 
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Growing Well
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How the nutrient concentration varies with time has a lot to do with what the plants are eating and this changes as the plants grow and fruit. Growing plants use more water and more nutrient.

I keep my reservoir at a certain level and measure PPm daily. When ppm and water drop, I add nutrient and water to keep reservoir up to its mark. If the solution doesn't drop below 1 gal, I do nothing, no matter the ppm change.

Keep a daily log of ppm, Ph and etc and this will all clear up for you with time.


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 Post subject: Re: ppm rising
PostPosted: Mon Jan 16, 2006 1:21 pm 
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deadleaf wrote:
hi guys thanks in advance for all the support...
ok here goes.....

i have a 4'x8' aeroponic unit with a 125litre reservoir.
All is fine, now at week 5 of flower and looking real good.

Concerning ppm's, i have read in a few articles stating that aeroponics prefer a lower ppm of around 700 in veg and 900 in flower.i have looked through the forum and you seem to always suggest to follow the recipe for succes in aero.....
However, in the last mix, i tried the full mix (flower stage2) which says 1500ppm or so...I got the ppm reading at that level for about 115 ltres of solution.After about 3 days the solution was at around 85 litres and the ppm had risen to 1800.



My question is as follows: if I get the ideal nute ratio, shouldn't it stay at the same level, the water and nutes being use at the same proportion? In the first few weeks when i started, i used half the amount and the ppm's were actually going down.
Thanks.


Deadleaf,
In your first example where the PPM's went down, your plants were using more nutrients than water, whereas in your second example where the PPM's went up your plants are using more water than nutrients. (Evaporation may also be a cause of PPM increase). Nonetheless, this is normal and OK as Willard points out plants will use varying amounts of both water and nutrients at different stages of growth. If it gets too strong (your second example) you can always dilute the solution; similarly, if it gets to weak you can always add nutrients, change your reservoir more often, or get a bigger reservoir.
Thanks for your question and continued support.
Customer Service,

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"Once in a while you can get shown the light, in the strangest of places if you look at it right"


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 Post subject:
PostPosted: Tue Jan 17, 2006 6:34 am 
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Seed

Joined: Sun Jan 15, 2006 11:55 am
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Thanks for the response.

As of now the perfect ratio for my set-up is 1100 ppm.At this ratio, the solution is being used with no drift (the water and nutrients are being used at the same rate).

According to the recipe for succes, however, I should be at 1900, and i'm affraid of over-fert.

So what do you guys think? Should I stick with 1100 or go with 1900 ???(or something in between??)

I'm just wondering if i should give them just the right amount or more than what they take, since the levels suggested seem really high....


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 Post subject:
PostPosted: Tue Jan 17, 2006 4:39 pm 
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Master Gardener
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deadleaf wrote:
Thanks for the response.

As of now the perfect ratio for my set-up is 1100 ppm.At this ratio, the solution is being used with no drift (the water and nutrients are being used at the same rate).

According to the recipe for succes, however, I should be at 1900, and i'm affraid of over-fert.

So what do you guys think? Should I stick with 1100 or go with 1900 ???(or something in between??)

I'm just wondering if i should give them just the right amount or more than what they take, since the levels suggested seem really high....


Deadleaf,
In our opinion you should feed your plants as much nutrient as they can handle; we call this the "scaffolding approach" to nutrient management. In other words, pump up your PPM values until you begin to notice slight marginal leaf tip burn, at this point back off the PPM of your nutrients enough so that the burn goes away. Now you are giving your plant as much as they can handle without over fertilizing. This approach should be used when one wants to provide as much nutrition as is possible for a given variety of plant. That having been said, if you are happy with the results you are getting and everything is going well, don’t mess with it at all.
Thanks for your questions and continued support.
Customer Service

_________________
"Once in a while you can get shown the light, in the strangest of places if you look at it right"


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 Post subject:
PostPosted: Wed Jan 18, 2006 8:18 am 
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Growing Well
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I am of the low ppm school.

In a recirculating system, the plants are going to see nutrient for 16 hours anyway so whatever nutrient is in solution will get to the plants.

I also grow chiles and recommended ppm for them is ~1500ppm and I never go over 500-600 ppm. The plants grow like crazy. I can get to about 1200-1400 ppm before plants start to get tip-burn.

You will develop your own data with time. Recording nutrient concentration and Ph is where a daily log is really helpful.


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 Post subject:
PostPosted: Wed Jan 18, 2006 7:53 pm 
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Good advice Willard. There is no substitute for careful observation over time.
Customer Service

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"Once in a while you can get shown the light, in the strangest of places if you look at it right"


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