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cation exchange capacity / coco article beginner friendly

bdomina

bdomina

Member
found an article on coco as a medium in general. In the article it explains cation (CEC) in a way that beginners like myself should probably be able to understand. below is a quote:

"Some coirs have been chemically treated, this is most often the case with loose pre-hydrated varieties versus compressed blocks. The treatment has been done to satisfy the cation exchange capacity (CEC) of the growing media. As a refresher, “cations” are positively charged ions, such as Calcium, Magnesium, Sodium, and Potassium. This means that the growing media will hold these ions in a matrix, releasing them as required by plants. There is one slight drawback to this. Until the cation exchange capacity of the growing media is filled, the growing media may hold positively charged nutrient ions, most notably calcium, in reserve, making them less available to plants. However, the cation exchange capacity (CEC) of the coir media is quickly filled, and actually assists calcium absorption in the crop cycle. To ensure optimum availability of all nutrients, supply additional calcium during the first week of growth or during the hydrating process of the coconut coir. Calcium supplement products are ideal for this. Some nutrients specifically formulated for coco tend to have elevated levels of calcium and magnesium while having lower levels of nitrogen. "




http://www.progressive-growth.com/article-coco-coir.php
 
L

LJB

thanks for posting. I think this is another piece to the puzzle:

Cucumber Cultivation in Energy-Saving Hydroponic System Using Coconut Coir as Growing Media

We investigated the productivity of cucumber and compared the changes in the nutrient concentrations of coconut coir and rockwool used as growth media. Higher yields (16%) with a higher proportion of marketable fruits were obtained in cucumber plants grown in the coconut coir medium. The concentrations of nitrate, potassium, magnesium and phosphorus increased in both media during the growing period. Potassium and phosphorus concentrations in coconut coir were two and eight times higher than those in rockwool. The electrical conductivity, potassium and phosphorus concentrations in coconut coir increased 2.3, 4 and 17 times, respectively compared with those in the nutrient culture solution, while the calcium concentration decreased by one-fifth in the coconut coir medium. The amount of exchangeable calcium was also reduced by more than half in the coconut coir medium through exposure to the nutrient solution. These results suggest that calcium ion was immobilized in coconut coir. The concentrations of the chemical components in cucumber leaf obtained in plants grown in the two media were not affected, despite the existence of significant differences in the nutrient concentrations of the two media.
 
Seed Buyer

Seed Buyer

Member
I have been using the purple bags of Bcuzz "buffered" coco. My thinking was that buffered coco had been treated w/ CA & MG so the grower did not need extra Cal-Mag. Would most agree that extra Cal-Mag is needed w/ buffed coco from Atami and Canna?
 
M

*mistress*

Member
Veteran
may use caution w/ so much ca initially... may lock out mg...

this may also be helpful:
Cation Exchange Capacity in Coco
https://www.icmag.com/ic/showthread.php?t=133012

posted +data in that thread...

should be noted that while the article cited
“cations” are positively charged ions, such as Calcium, Magnesium, Sodium, and Potassium.
Click to expand...
... did not go on to point out that positively charged metals repel ea other... potassium (k+) repels calcium (ca+)... they can be bonded in solution by attaching anion (negatively charged non-metal)...

example:
nitrate (n03-) - negatively charged non-metal anion
calcium (ca+) - positively charged cation metal

calcium nitrate solution=can03

this cation bonded to anion... if imbalance in solution/media, like charges repel ea other.
humic & fulvic acids seem to buffer, chelate & catalyze nutrients to assist easier ionic passage thru cell walls...

hope this helps. enjoy your garden!
 
L

LJB

some of this doubles up on what *mistress* has posted, but I found it all invaluable, especially the highlighted parts.

It's KNNA on coco, edited for clarity:

Coco's main characteristic which does it different from most other hydro mediums is its very high CEC (Cation Exchange Capacity), from 7 to 20x higher than perlite, rockwool, hydroton, etc. This means coco may store very large amounts of nutrients that are uptaken as cations: micros, Ca, K, Mg.

Practical consequences of that are:

You need to keep cations balanced in the media. Its accomplished by knowing your nute profile and managing the pH according to it: ph below 5.8 achieves higher Ca uptake and lower Mg uptake, thus you reduce the Ca stored in the coco and increases Mg. By using ph over 5.8, you achieve the inverse. Keeping the amounts of Ca and Mg balanced in the coco is the key to heving the best yields and avoiding problems. And more importantly, it allows you to not flush until preharvest. Coco doesn't react well to flushing, as growing in it is based in its high CEC. Anyway, after any flush in coco you should water feed inmediately after, or plants could develop have an N deficiency quickly.
Click to expand...

on flushing coco:

It's of limited value only when the excess is of cations, and very specially, Ca. Due the high CEC, pH and EC of runoff may be very misleading, and it shouldn't be used as reference. Adjust the watering solution and forget the runoff, as it's figures may be much higher than those measured in other mediums without any problems for the plants. Flushing works perfect against a excess of N (NO3-) or P. But if the problem is excess Ca, then flushing wont solve the problem, it willl just help a bit and may aggravate other problems induced for excess Ca. K, still being uptaken as cation, is easily flushed too. But Mg and Ca excesses don't respond well to flushing. Both get bonded to over 90% of total coco colloids in normal conditions, so keeping an equilibrium between the two is the key when growing in coco.

If MG accumulates, this isn't a major problem, because Ca has a stronger affinity (electrical charge) than Mg++, so adding a bit Ca to the flush water will easily fix an unbalanced system due to excess Mg. This often happens when consistently using a too low ph or adding excess Mg, usually in the form of Epsom salt supplementing, which shouldnt be used "preventively", but just when an Mg deficiency appears.

When the excess is of Ca, then solving it is much more complicated. Flushing with plain water doesn't work. Flushing with Epsom salts doesn't and also causes a major K deficiency. Only cutting the Ca feeding and using a low ph (below 5.8 and likely 5.3-5.6) to help in Ca uptake works. Reducing humidity to increase transpiration helps a bit too. Ca excess only gets fixed by Ca uptake itself. And because Ca is by far the element with the slowest (?) uptake, it's not actively uptaken by plants. Its absorption fully relies on water uptake which means the key to avoid major problems is avoid an accumulation of Ca in the media. Other problems are much more easily solved, while fixing a Ca requires an excess of patience.

Thats why I often advise people to use a relatively lower pH in coco than on other hydro mediums. It's the way to avoid severe problems, as once the coco has been loaded with too much Ca, there is little to do.
Click to expand...
 
SneakySneaky

SneakySneaky

Active member
Veteran
i like it, now i gotta re-read it to make sure i know it lol anybody gotta advil my head hurts maybe a bongrip will do the trick :)
 
C

Castelvetro

Member
i have no idea how this info is supposed to make any differance in growing, if it helps some of u great but i dont understand how, u simply read up on the coco specific nutes and add water, if you ph is low it must be raised n vice versa if its to high as this everyone knows effects cal,mag absorbtion. but do u really need a phd iin this crap to grow a plant. i sure dont . and im not trying to be negative its jsut that any newbie out there shouldnt let this stuff shy him away from the ease of coco with a decent nute and some phd tap water n success on there first try.

if it aint broke dont fix it and there plenty of nutes to use that eliminate any other know how then adding a few teaspoons of them in a gallon of water-
 
OPT

OPT

Member
When using "Tap water", is it still recommended that you bubble if for 24 hours to evaporate the cholorine or is that not needed?

OPT
 
C

coconaut

GrnMtnGrwr said:
Why is that? I've run into a lot of issues when not letting my water sit for 24+ hours.
Click to expand...

The amount of chlorine in tap water is quite minimal. Whether you're brewing a tea, or watering your plants with tap water, there are too many organisms in your [compost] or in your pots to be significantly affected by the small amount of chlorine in the tap water.
If you ran a pot under the tap for an hour or two, that would probably kill most of the microheard, but even still you could never sterilize something with just tapwater.
 
GrnMtnGrwr

GrnMtnGrwr

Active member
Veteran
coconaut said:
The amount of chlorine in tap water is quite minimal. Whether you're brewing a tea, or watering your plants with tap water, there are too many organisms in your [compost] or in your pots to be significantly affected by the small amount of chlorine in the tap water.
If you ran a pot under the tap for an hour or two, that would probably kill most of the microheard, but even still you could never sterilize something with just tapwater.
Click to expand...

All the other growers I've talked to, and my personal experiences, lead me to believe if you're using tap water, letting it sit for a while to let the chlorine evaporate is beneficial. :dunno:
 
C

coconaut

Well now you can say that not all growers you've talked to believe it.
And I know there are others out there that support what I'm saying.
Let your water sit by all means, it doesn't cost you anything..
But consider, some municipalities also use chloramine which doesn't evaporate.
If you really want make sure.. you can buy chlorine/chloramine removers from aquarium supply stores.
 
GrnMtnGrwr

GrnMtnGrwr

Active member
Veteran
Yeah I always wondered about the chloramine content. Well maybe I'll set a few plants aside this grow and treat them the same, except use fresh water from the tap each time and see if there's any difference. I definitely think it depends on how much your municipality puts into the water.

So you're basically saying that chlorine only affects the microherd? Does this mean that if growing hydro, there's no point in letting the water sit? :wave:
 
C

Cannoiseur

Member
Most municipalities treat with <1ppm of Cl- or chloramine. As was stated, this is sufficient to disable microbes that might be attempting to survive within the pipes in your house, but a community of microfauna as populous as you'll find in soil or any sort of compost tea is far too resilient to be damaged by simply tap water. if you continuously flushed with tens of gallons of tap water then potentially the Cl- could displace other anions within the bonding sites and damage your "herd" via eventual accumulation, but for regular watering it's not something you should be worried about.
 
C

coconaut

Chlorine is an element, it occurs naturally in nature, plants do need very small amounts of chlorine themselves.
A 30% bleach solution contains about 3% chlorine, at this concentration the solution will sterilize whatever it is applied to in about 10 minutes.
A 10% bleach (90% water) solution is good enough for disinfecting surfaces in about the same amount of time.
Tap water contains less than 5ppm of chlorine.

Yes, chlorine only affects the microheard, if I remember correctly it's not the actual chlorine, but when chlorine is added to water it causes chemical reactions that produce some kind of acid that disrupts the cell walls of living organisms.
Whether you're growing hydro, soil, coco, whatever I am of the opinion there is no reason to let the water sit.
 
C

Cannoiseur

Member
Lol yes. Regular water contains bits and pieces of H+ ions (in fact pH stands for Power of Hydrogen, and is a negative logarithmic scale measuring the concentration of H+ ions in solution). When Cl is in water it bonds with those hydrogen ions to produce HCl, also known as hydrochloric acid.

I don't think I need to explain how hydrochloric acid is bad for living organisms ;)
 
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