Runnoff cannot be trusted.

Billy the Mountain

Billy the Mountain

Well-Known Member
PJ Diaz said:
Yes, EC will rise over time in coco, but it's not a waste of time to check runoff, if you know how to read your results appropriately. I don't check my runoff these days, but I have in the past, and it helped me to dial my feed in.
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That's not been my experience using coco with both cannabis (indoors) and hot peppers (outdoors)

EC doesn't rise over time unless I feed too much; my runoff EC is consistent

There's nothing inherent to coco, including CEC, that would cause the EC to rise over time
 
PJ Diaz

PJ Diaz

Well-Known Member
Billy the Mountain said:
That's not been my experience using coco with both cannabis (indoors) and hot peppers (outdoors)

EC doesn't rise over time unless I feed too much; my runoff EC is consistent

There's nothing inherent to coco, including CEC, that would cause the EC to rise over time
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The high CEC of the cellulose in coir traps cations from the solution and releases them at root absorption. The cellulose and lignins in coir are highly electronegative molecules that absorb or “trap” cations. So, the absorptive capacity of coir is high, with a very large surface area in the granular structure of the coir. These absorbed cations will be exchanged for other cations in solution. The CEC changes with pH since H+ is a very small cation and is also attracted by the cellulose in coir.
 
Billy the Mountain

Billy the Mountain

Well-Known Member
PJ Diaz said:
The high CEC of the cellulose in coir traps cations from the solution and releases them at root absorption. The cellulose and lignins in coir are highly electronegative molecules that absorb or “trap” cations. So, the absorptive capacity of coir is high, with a very large surface area in the granular structure of the coir. These absorbed cations will be exchanged for other cations in solution. The CEC changes with pH since H+ is a very small cation and is also attracted by the cellulose in coir.
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I understand CEC

How does this relate to the premise of EC rising over time being an inherent property of coco and somehow related to its CEC?
 
kwigybo88

kwigybo88

Well-Known Member
Billy the Mountain said:
I understand CEC

How does this relate to the premise of EC rising over time being an inherent property of coco and somehow related to its CEC?
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Fibers break down over time, creating new cation sites which have to be satisfied. That along with any level of evaporation will gradually raise the EC.

Getting your runoff to match your input is easy. Doesnt mean the root zone or medium EC isnt rising. And it doesnt mean you're feeding the plant optimally.
 
Billy the Mountain

Billy the Mountain

Well-Known Member
kwigybo88 said:
Fibers break down over time, creating new cation sites which have to be satisfied. That along with any level of evaporation will gradually raise the EC.

Getting your runoff to match your input is easy. Doesnt mean the root zone or medium EC isnt rising. And it doesnt mean you're feeding the plant optimally.
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Yes, but its a cation exchange; the net ionic change is zero.

My runoff is generally higher than the input but remains consistent; maybe not optimal, but it stays where I want it.
 
Star Dog

Star Dog

Well-Known Member
There's a guide available called understanding and maintaining nutrient solution by Paul Fowler it's an easy read and let's you understand nutrient maintainance.
 
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