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Coco vs Hydroton vs Rockwool minicubes

3 media side by side comparison.

3 blueberry clones all from the same plant. They were all transplanted at the same time/same size:

  1. back left, coco
  2. back right, hydroton
  3. front, rockwool minicubes

2 gallon buckets, ebb and flow system from a common rez.
CNS17
1200 watts in a growzilla hood:
600 watt Lumatek with EYE hortilux Super HPS
600 watt Lumatek with SunMaster Cool Deluxe conversion bulb

I played musical chairs once a week to try to ensure each plant received equal light spectrum.

As you can see, the coco plant is much larger and heavier than the other two. But I do have to admit that the plant in hydroton is noticeably heavier in trichomes. It is also holding its green much longer into flower than the other two.

Granted, this is inherently a less than perfect test, since each media has slightly different nutrient/watering requirements which are not served by the shared reservoir and watering schedule. But I still thought the results were pretty amazing.





 
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word

Member
great job! coco is nice. so glad to see it get its respects.

how long was the veg? would like to see that side by side from clone, but i get the point.

also how often do you e&f the table? coco will retain way more moisture than does rockwool and especially pellets.... i flood my coco table once, every 1 to 2 days.. rockwool needs probably a minimum of 2 floods per day and pellets maybe 4-5 or more per day.... just wondering how you managed the 3 in 1 table?
 
Thank you for the comments. I thought it was an interesting experiment.

You are exactly right. I was forced to overwater the coco and rockwool.

I was watering every 4 hours during lights on, plus once during lights out.

As you can imagine, the coco stayed quite wet. As a result, the root system was not forced to expand in search of water and nutrients. It didn't even fill the entire 2 gallon bucket - the bottom 2 or 3 inches had virtually no roots!

I'm sure this also contributed to the coco and rockwool plants yellowing much faster than the hydroton - they just didn't have the roots to support the canopy.

Obviously I will be going all coco this next grow and will water on a schedule more appropriate for coco. I look forward to the results!
 
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FreezerBoy

Was blind but now IC Puckbunny in Training
Veteran
Here's a highly unfair comparison.

When I grew in 4" Rockwool with Flood and drain, I chopped the plants with a pair of needle nose dykes. Since the switch to DWC, I use a tree pruner.



It's not fair because I also switched from a 150HPS to 250CMH (33 watts per sq ft to 56 watts) Still ...
 
FreezerBoy said:
Here's a highly unfair comparison.

When I grew in 4" Rockwool with Flood and drain, I chopped the plants with a pair of needle nose dykes. Since the switch to DWC, I use a tree pruner.



It's not fair because I also switched from a 150HPS to 250CMH (33 watts per sq ft to 56 watts) Still ...

I'm curious what you mean by 4" rockwool.

Are you saying you were only using the 4" cube with no underlying slab?

That's just cruel. :spank: :tongue:
 
fjällhöga said:
most likely he refers to the size of the cube ...

Not sure if you're being derisive, but yes I understand that refers to the size.

I'm just curious if that's ALL he was using. Obviously 4" cubes are never meant to be used standalone, but rather on top of some larger media.

If the plants roots were being confined to 64 square inches of media, that would have been an unfair experiment indeed. :wink:
 
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imnotcrazy

There is ALWAYS meaning to my madness ®
Veteran
Actually, size of media doesn't really take affect in E&F if you flood often enough to prevent under-watering. I've grown from seed/clone through harvest in only 4" RW cubes & quart sized pots full of Hydroton. Both hold water/nutes about the same length of time and flooding every 3-4 hours will keep the plants happy.
 
imnotcrazy said:
Actually, size of media doesn't really take affect in E&F if you flood often enough to prevent under-watering. I've grown from seed/clone through harvest in only 4" RW cubes & quart sized pots full of Hydroton. Both hold water/nutes about the same length of time and flooding every 3-4 hours will keep the plants happy.

I understand what you're saying, but I must humbly disagree. It will have an impact on plant size.
 

imnotcrazy

There is ALWAYS meaning to my madness ®
Veteran
SIX plants from seed in 4" RW cubes. Yes it's a mess but needed to just get a run out so I flowered the moms. But you can see how much canopy there is for a 6- 4" cubes:






 
word said:
would like to see that side by side from clone, but i get the point.

Yeah, I wish I had kept at least a weekly picture journal. Here's a shot of them right after transplant though. So you can see they all started out very similar.


 
B

British_Bulldog

It's an interesting experiment, but I don't think the results are valid, as you overwatered the rockwool and coco.

I think what it proves is that coco grown plants can handle overwatering better than rockwool cube grown plants, not which is the best medium to use (if you water properly).

I've grown in all these mediums too, and enjoyed good results with all of them.
 
British_Bulldog said:
It's an interesting experiment, but I don't think the results are valid, as you overwatered the rockwool and coco.

I think what it proves is that coco grown plants can handle overwatering better than rockwool cube grown plants, not which is the best medium to use (if you water properly).

Quite true, as I admitted in my original post.

However, the size difference between the (overwatered) coco plant and the hydroton plant (all other conditions the same) was quite startling.
 
B

British_Bulldog

KoD, you'll find that if you let the rockwool dry out more, and don't overwater, it can produce the same results as Coco.


Peace
 

Rosy Cheeks

dancin' cheek to cheek
Veteran
Very interesting line-up. Even though it lacked scientific rigour, it still gives an indication how the different mediums treat the roots.

As a long time user of both rockwool and hydrotones in NFT, and now soon two years of growing in coco as well, I've done all three, but never in a side-by-side.

To start with, in NFT, the rockwool and hydrotones are simply used as starting mediums, a root propagator for the young clone or seedling. The roots then spills out on the NFT trays and into the reservoir, which is the real medium.

I've also used a Flo-Gro with hydrotones though, which is a re-circulating drip system a la Waterfarm.

After experimenting with different coco mixes, I went 100% coco, using them in pots either top fed by hand, or bottom fed on trays. The principle here is run to waste, or constant flow.

I do believe that if you had gone constant drip or flow with the hydrotones, you would have seen a whole different result in terms of growth. Hydrotones is a intert medium, meaning that it has close to zero absorption capacity (while the aerating capacity is great). The whole principle behind an ebb and flow system is of course to supply a nutrient solution to an absorbing medium, that holds on to the liquid and distributes it to the root system. So the root system in the hydrotones are dependent on water pockets, spreader mats and spreading out on the trays in order to find liquid.

I can see how the rockwool waterlogged the medium, but not the coco. While coco has a great absorption capacity (8-9 times its own weight), the coarse coir fibres still provides sufficient aeration for roots even when totally saturated. I've only seen waterlogging in 100% coco coir when the coco was re-cycled (fibers degraded) and the root system was underdeveloped. I've run coco coir pots bottom fed on constant flow trays, without a hint of waterlogging.

Rockwool is also an inert medium, but thanks to its porosity it manages to retain liquid, sometimes a little too well. Young plants beware. Its Caption Exchange Capacity (the capacity to 'hold on' to certain nutrients and later re-distribute them) is zero, just as water, while coco has a tendency to hold on to certain nutrients (initially at least), such as calcium and potassium.
Rockwool therefore holds an advantage over coco if the nutrient (solution) flow is constant, while coco holds an advantage in an ebb and flow system.

Therefore, the medium most suited for this kind of system/feeding is coco, rockwool less, and hydrotones even less.
Set it up differently, and you'll get different results.

KissOfDeath said:
As you can imagine, the coco stayed quite wet. As a result, the root system was not forced to expand in search of water and nutrients. It didn't even fill the entire 2 gallon bucket - the bottom 2 or 3 inches had virtually no roots!

Let me expand a little on this. Roots do not grow in a dry medium. In a wet medium they will grow towards the water/mineral source (higher concentration of water and nutrients), always. They will therefore always invest the most saturated parts of the medium, and if they don't, it's either because they couldn't, or because they didn't need to.
One thing worth talking about is the CEC capacity of coco, allowing it to store/concentrate nutrients only to release them to the roots later. A well-saturated coco coir medium therefore - it seems - allows roots to feed more efficiently on a smaller surface than peat soil (lower CEC) or rockwool/hydrotones (zero CEC).

So, rather than saying that the roots didn't expand (in coco) because the medium was too wet, let's say that you were using too big pots, because with coco you can reduce the size and get the same results, the proof being that your coco plant outdid the others with a smaller root system.
 

SirSmokalot

My Zips Be So Fluffy The Whole Town Love Me
Veteran
Rosy Cheeks said:
Very interesting line-up. Even though it lacked scientific rigour, it still gives an indication how the different mediums treat the roots.

As a long time user of both rockwool and hydrotones in NFT, and now soon two years of growing in coco as well, I've done all three, but never in a side-by-side.

To start with, in NFT, the rockwool and hydrotones are simply used as starting mediums, a root propagator for the young clone or seedling. The roots then spills out on the NFT trays and into the reservoir, which is the real medium.

I've also used a Flo-Gro with hydrotones though, which is a re-circulating drip system a la Waterfarm.

After experimenting with different coco mixes, I went 100% coco, using them in pots either top fed by hand, or bottom fed on trays. The principle here is run to waste, or constant flow.

I do believe that if you had gone constant drip or flow with the hydrotones, you would have seen a whole different result in terms of growth. Hydrotones is a intert medium, meaning that it has close to zero absorption capacity (while the aerating capacity is great). The whole principle behind an ebb and flow system is of course to supply a nutrient solution to an absorbing medium, that holds on to the liquid and distributes it to the root system. So the root system in the hydrotones are dependent on water pockets, spreader mats and spreading out on the trays in order to find liquid.

I can see how the rockwool waterlogged the medium, but not the coco. While coco has a great absorption capacity (8-9 times its own weight), the coarse coir fibres still provides sufficient aeration for roots even when totally saturated. I've only seen waterlogging in 100% coco coir when the coco was re-cycled (fibers degraded) and the root system was underdeveloped. I've run coco coir pots bottom fed on constant flow trays, without a hint of waterlogging.

Rockwool is also an inert medium, but thanks to its porosity it manages to retain liquid, sometimes a little too well. Young plants beware. Its Caption Exchange Capacity (the capacity to 'hold on' to certain nutrients and later re-distribute them) is zero, just as water, while coco has a tendency to hold on to certain nutrients (initially at least), such as calcium and potassium.
Rockwool therefore holds an advantage over coco if the nutrient (solution) flow is constant, while coco holds an advantage in an ebb and flow system.

Therefore, the medium most suited for this kind of system/feeding is coco, rockwool less, and hydrotones even less.
Set it up differently, and you'll get different results.



Let me expand a little on this. Roots do not grow in a dry medium. In a wet medium they will grow towards the water/mineral source (higher concentration of water and nutrients), always. They will therefore always invest the most saturated parts of the medium, and if they don't, it's either because they couldn't, or because they didn't need to.
One thing worth talking about is the CEC capacity of coco, allowing it to store/concentrate nutrients only to release them to the roots later. A well-saturated coco coir medium therefore - it seems - allows roots to feed more efficiently on a smaller surface than peat soil (lower CEC) or rockwool/hydrotones (zero CEC).

So, rather than saying that the roots didn't expand (in coco) because the medium was too wet, let's say that you were using too big pots, because with coco you can reduce the size and get the same results, the proof being that your coco plant outdid the others with a smaller root system.
K+ very accurate and informative post. keep doing your thang rosey
 
G

Guest 18340

Right on Rosy Cheeks, one of the best explanantions i've heard so far :joint:
 
Great post, Rosy!

Plenty of food for thought.


Rosy Cheeks said:
Let me expand a little on this. Roots do not grow in a dry medium. In a wet medium they will grow towards the water/mineral source (higher concentration of water and nutrients), always. They will therefore always invest the most saturated parts of the medium, and if they don't, it's either because they couldn't, or because they didn't need to.

But isn't over-watering the reason they didn't need to?

To attack it from a different angle - If I had only watered the coco once per day (let's assume it doesn't dry out), wouldn't the root mass have been more developed?
 
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