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COCO COIR Coco question

9fingerleafs

9fingerleafs

New member
Hello my fellow growers. I’m finally switching to coco. I bought a 230litters pack of coco fiber from a “natural” source, meaning it’s not branded and locally sourced. Anyway my question is should I rinse/buffer once or twice? In GWE says a quick 10 min soak it’s enough but I’ve seen other places say it needs two 8hours soaks in order to buffer correctly for cannabis. Also been thinking, is it a good idea to mix the 130litters of fox farm soil I got left with the coco?? If so what ph should I aim for? Thanks in advance :)
 
That's a good question about mixing it with soil. I've always just bought the coco that's ready to go in the bag. But from what I have read about the bricks, most videos I have watched say to do it for a long time.

I would go with the 8 hours and make sure to put plenty of CalMag in it to precharge it with. Otherwise the coco will take it all and not give the plant enough. I give CalMag with every feeding and it doesn't seem to hurt them.

Coco is awesome. I tried dwc at first and got root rot. Switched to coco and never went back.
 
Are you going to use perlite as well ?

If your wanting to do full hydroponics then its not a good idea to mix with soil. Mixing with soil, looses some of the benefits that coco and perlite offer. However many people use soil and then apply amendments such as coco and perlite, to allow better drainage and air availability to roots.

I have switched to 50/50 coco perlite mix this grow, with daily fertigation. And i will never go back. The consistancy of development seen with this has been great.
 
Yeah I think I’m gonna do first a 8hour soak with my 1.4EC deep well water and then another one with ro water and calmag. That way I don’t waste nutrients
 
I actually didn’t thought about that. Now that you mention it I should get some perlite. I think I’m gonna keep separate my soil from the coco and that way I can even do a side by side with clones to really see the difference.
 
Yea give it a go.

With regards to buffering coco, the idea is to fill as much of the cation sites as possible, due to the natural tendancy for coco to leach cations such as calcium and magnesium from the nutrient solution. Unbuffered coco, can create cal-mag deficiencies as these nutrients are made unavailable to the plants as they are held too strongly by the cation sites.

Coco naturally has lots of sodium and potassium, so a initial flush with low EC water is recommended to release some of the sodium in the media. The rinse is also important for ridding the fine particles from coco, which creates further problems by increasing the available cation cites. Which is what we are trying to avoid in coco, we want as inert media as possible. Making the nutrient solution we provide, as the main source of nutrients.

You then want to buffer coco with calmag, to release the left over potassium and replace with cal-mag to prevent the stripping of these minerals from the nutrient solution as previously discussed. The amount used is typically around 200-400ppm or 0.1-0.2 EC. You want to buffer the coco for at least a few hours, with thorough mixing to expose new cation sites to the cal-mag. This can be repeated by rinsing the coco again to drain off the potassium released during the first buffer and then repeating the process again. Two 8 hour buffers should be plenty, but you can get away with just a single buffer for a few hours.

During the grow, the coco will still want to strip some of that cal-mag, but it will be much less compared to unbuffered coco and you will not have to use as much cal-mag.
 
Yea its a bit of work, but important. I use pre buffered coco because im lazy. But doing it yourself woud likely be cheaper ? But i have noticied that i have to use high dose cal-mag initially, as the media is not thoroughly buffered.
 
yes for sure, i spent 25 USD including shipping for 230liters, thats almost four bags of prebuffered coco that cost 20 USD each plus shipping
 
After I rehydrate with ph water or if im using permixed coco, I Just put my coco/perlite in a 5 gal smart pot and run 2 gallons of ph 6.2 water with calmag through the pot like a flush.
Done.

There is a different in Coco.
Inland coco (not grown next to the sea) does not contain the salt content that, Coastal grown coco would. So it is worthy of checking were it was grown if you can.

I have amended Coco with soil before, work great for what I needed, didn't have Liquid Fertilizer till flowing and it got my there. I Ph'ed my water at 6.5.

good luck 9'
 
Hi. A drop of water can also contain 400ppm Ca. Unbuffered coco needs around 1 mole, 40 g, calcium for every 5Kg dry coco and tens of hour as cation exchange taks time. Watering, even tens times, with 200ppm Ca has almost no effect on CEC site.

I dont think rinsing can be an effective way to remove fine particles. But it is definitely effective at lowring Na, K and specially Cl, S level within the media.
We cant buffer Ca with simple watering.
 
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Coco CEC is around 50-100 MEQ per 100g dry coco; or even more depending on particle size. A 5 gal pot has around 1kg dry coco. Using this numbers we can guess that a 5 gal pot of coco has around 500-1000 MEQ CEC. 120 and 240PPM Ca equal 6.0 and 12.0 MEQ/l Ca respectively. Now compare 6-12 MEQ/l Ca with 500-1000 MEQ total CEC within the media.

I can go deeper in details if you want more.
 
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I already did an 8 hour soak with deep well water at 1.4 EC, drained, dumped water and repeat. This time they will soak 14 hours till tomorrow morning. Then I wil rinse with high dose calmag and mix with perlite
 
Yes more detail will be great. Im am genuinly interested. I have pretty deep level understanding in plant biology and other fields. So complexity is nothing new to me. I have researched enough to understand the basic principles in soil biology. But nothing major, major textbooks on plant biology typically dont go into much detail.

Based on your previous comments, were you suggesting that the EC i suggested to buffer with is too low ?. I wont argue that as i buy product thats pre buffered so this was only an assumption. So to also be clear, you also say that the required amount of calcium to buffer with is dictated based on the volume of media. So the EC required will be dependent. ?

Whats most interesting is that you suggest buffering is practically ineffective when done for less than 24hrs ?

Good to know that rinsing does leach out certain minerals well. I wondered whether it did anything.

I have seen that some coco can be very dusty, with large amounts of fine particles. Using the right mesh filter, this peat can be removed. Which would be beneficial IMO.
 
The water turns brown very quickly and a fine dust goes tru the fabric and ends up in the bucket. I can only assume all kinds of things are being flushed. I don’t know where the coco came from. But I know I will dump the finest dust that sank to the bottom and use only the top 4/5ths of quality fiber. When I rinse. Should I flush until the runoff is not dark brown??
 
100g dry coco heavily loaded with 0.85-2.36mm particle size with very litte fine particles absorbs water 7 time of its weight, reaching 1.4L when it is saturated(So Water holding Capacity of this media is 50%. Good to know that 75-50% of this WHC is plant unavailable water; PUW). Lets say Cation Exchange Capacity of this media is 50 meq and Anion Exchange Capacity is 0. Potassium, Sodium, Calcium and magnesium in the CEC are 45%, 15%, 0 and 0 respectively. The solution i use for veg has the composition of 5 meq/l Calcium(100PPM), 3 meq/l Magnesium and 2.0 meq/l Potassium. So total cations are 10.0 meq/l. If i use this solution to hydrate dry coco, Cations start to exchange but No cation can exchange without reaching the surface of the particles of the media. So this equilibrium needs time specially at lower "temperatures and concentrations". At the beginning there are 3.5meq Calcium, 2.1 meq Magnesium and 1.4 meq Potassium in 0.7L water that our sample can hold. these are 7.0 meq cations. Here cation exchange sites can hold (1 - 7.0/57) of the total specific cation in the volume. This means 12.2% of tottal specific cation within the volume will be remain in the solution and the rest will be positioned in the CEC sites.
If we do some mathematics we get 3.5, 2.1, 23.9 and 7.5 meq Calcium, Magnesium, Potassium and Sodium respectively in the volume and 12.2% of these are 0.43, 0.26, 2.94, 0.92+ 2.4 meq of the other cations, including Hydrogen ion, that remain in the solution.
Although we started with dry coco(hydrated coco contains water so it can't hold all of 0.7L) and higher Ca ratio in solutions compare to solutions formulated for low CEC substrate, these numbers and simple model show that chemical properties of the unbuffered coco needs to be fixed before planting unless we have a nutrient solution composition that formulated to work at that circumstances.

Any change in solution composition effects CEC sites. These changes in CEC sites need time depending on both temperature and concentration as i said. 24H sounds enough even at 20°C and concentrations as low as several times of that is used for feeding plants But the EC is not the correct quantity to know whether it's enough to shift Cations ratio within the media or not. You have to look at the number of cation moles you have in the solution not just EC.
 
Iammygod said:
100g dry coco heavily loaded with 0.85-2.36mm particle size with very litte fine particles absorbs water 7 time of its weight, reaching 1.4L when it is saturated
Click to expand...

Isnt 7 times 100g 0.7 litres ?? As water weight is 1/1 with volume.

Iammygod said:
(So Water holding Capacity of this media is 50%. Good to know that 75-50% of this WHC is plant unavailable water; PUW).
Click to expand...

Yes, so from memory the water availability to plants is determined by the difference in field capacity and the wilting point. Can you provide data that shows this characteristic of coco coir ?

Iammygod said:
Lets say Cation Exchange Capacity of this media is 50 meq and Anion Exchange Capacity is 0. Potassium, Sodium, Calcium and magnesium in the CEC are 45%, 15%, 0 and 0 respectively. The solution i use for veg has the composition of 5 meq/l Calcium(100PPM), 3 meq/l Magnesium and 2.0 meq/l Potassium. So total cations are 10.0 meq/l. If i use this solution to hydrate dry coco, Cations start to exchange but No cation can exchange without reaching the surface of the particles of the media. So this equilibrium needs time specially at lower "temperatures and concentrations".
Click to expand...

You say that cations start to exchange with hydration but no cations can exchange without reaching the surface of the particles of the media. This is not making sense to me and sounds a little contradicting. Care to elaborate ? Are you suggesting that cations initially start to exchange, but takes time for the cations to interact with exchange sites. Does this time factor have anything to do with the water potential through the media? Or is it simply the characteristics of adsorption.


Iammygod said:
At the beginning there are 3.5meq Calcium, 2.1 meq Magnesium and 1.4 meq Potassium in 0.7L water that our sample can hold.
Click to expand...

You now say 0.7L so i assume it was just a error. :)


Iammygod said:
These are 7.0 meq cations. Here cation exchange sites can hold (1 - 7.0/57) of the total specific cation in the volume. This means 12.2% of tottal specific cation within the volume will be remain in the solution and the rest will be positioned in the CEC sites. If we do some mathematics we get 3.5, 2.1, 23.9 and 7.5 meq Calcium, Magnesium, Potassium and Sodium respectively in the volume and 12.2% of these are 0.43, 0.26, 2.94, 0.92+ 2.4 meq of the other cations, including Hydrogen ion, that remain in the solution.
Click to expand...

Yes i seem to understand you here.


Iammygod said:
Although we started with dry coco(hydrated coco contains water so it can't hold all of 0.7L) and higher Ca ratio in solutions compare to solutions formulated for low CEC substrate, these numbers and simple model show that chemical properties of the unbuffered coco needs to be fixed before planting unless we have a nutrient solution composition that formulated to work at that circumstances.
Click to expand...

Yes, i assume the nutrient solution for the circumstances you speak of where coco is unbuffered, would be that where the feeding solution compensates for the cations lost to the coco. So in other words, you not only feed your plants, but also your media (coco) as it would take its share of the available nutrients (mostly calmag due to their higher affinity with cation sites).

Iammygod said:
Any change in solution composition effects CEC sites. These changes in CEC sites need time depending on both temperature and concentration as i said.
Click to expand...

So the quantity of solution used can change the time that cations take to adhere ?. What formula or data can you provide that shows how long a certain application would take. For what reasons do these factors have an effect on time.

Iammygod said:
24H sounds enough even at 20°C and concentrations as low as several times of that is used for feeding plants But the EC is not the correct quantity to know whether it's enough to shift Cations ratio within the media or not. You have to look at the number of cation moles you have in the solution not just EC.
Click to expand...

So are you saying that the quantity of cation sites (which can be calculated by the volume of coco), dictates how much nutrient solution is needed for appropriate buffering. And also that the EC is not a ideal quantifier. As just as you previously stated, a single drop can be 400EC. But you need to calculate by quantity of cations within a solution and not by concentration (quantity vs concentration basically).


Overall i believe i understand what you are saying. And i must thank you for taking the time to do that in such a way that made sense. Hopefully you can extend on this with the further questions i have provided. I am very excited ^.^
 
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