No roots!

Well, i wouldn't say that Rockwool and DWC aren't compatible.

What i would suggest is this, Veg your plants as long as you see fit in your rockwool cubes, just make sure roots are sufficiently coming out the bottom of the cube (more than one tiny root poking through).

Put a thin layer of hydroton across the bottom of your netpot (like 1 rock high...) then set your rockwool cube with roots coming out of the bottom on top of that thin layer of rocks. gently fill the rest of the net pot with hydroton until it's full to your liking. Then place the netpot into your res/solution/5 gal bucket...whatever you are using...keep the water level just high enough to touch the thin layer of rocks...maybe touching the bottom of the rockwool. As long as you have sufficient aeration the roots will explode. After about 3 days you should notice some roots poking down through the bottom of the net pot. Once that happens simply drain just enough water so the roots are in the solution but the bottom of the net pot is above the water. That way the roots will continue to grow into the solution and the rockwool won't be soaking.

dunno if that's the best way...but i've been doing it over and over now with great results.

best of luck
Skeet

PS - Also...make sure your res is LIGHT PROOF and water temp is cool. I wrap my 5 gallon buckets with black plastic. Others use duct tape or black spray paint.

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Originally Posted by SpaceNeedle

That's your problem. Cubes, ESPECIALLY Large cubes like yours are not meant to be in a DWC, you will drown your plants, or at the very least they cannot thrive. When there is that much rockwool it will never get a chance to dry so that your plant gets oxygen.

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SpaceNeedle, please get your facts right before you post.

#1 - Rockwool and hydrotron work fine together. A lot of growers use them that way - a smallish RW cube to start with, and then set that in a net pot full of hydrotron.

#2 - Rockwool and DWC systems work fine together too. Again, a lot of growers have done that.

#3 - In a DWC your grow medium does NOT need to dry out and your plants won't drown. Think about it - in a DWC system your plants sit in a big bucket of water. Oxygen is added directly to your nutrient solution by the air stones that should be running constantly. Additional oxygen from the air is not necessary.



To OP: It's normal for it to take a bit for your roots to reach the water line, and it's also normal for growth to be a tad slow until that happens. You may want/need to hand water (use the water out of the reservoir if you can) a few times a day to keep your plants happy and speed things up a bit until then. Otherwise, as long as your plants are healthy, just be patient. You could also set up some sort of drip line that feeds out of the res, if you want.

If paperchaser gets his DWC going, and he has a plant sitting in a net pot with a 5" rockwell cube sitting in some clay pellets, and if there are none or very few roots coming out of that 5" cube, he runs the water level in the bucket right up to the bottom of that rockwell cube, there is no way that plant is going to thrive.

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Originally Posted by SpaceNeedle

If paperchaser gets his DWC going, and he has a plant sitting in a net pot with a 5" rockwell cube sitting in some clay pellets, and if there are none or very few roots coming out of that 5" cube, he runs the water level in the bucket right up to the bottom of that rockwell cube, there is no way that plant is going to thrive.

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There's this little thing called capillary action - aka wicking - that comes into play, especially with rockwool. If the bottom of the cube is touching the water it will wick the water upwards to the plants roots.

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Originally Posted by Help_Needed

There's this little thing called capillary action - aka wicking - that comes into play, especially with rockwool. If the bottom of the cube is touching the water it will wick the water upwards to the plants roots.

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PRECISELY!!!
The cube will never get a chance to dry out, and the plant will develop root rot!

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Originally Posted by SpaceNeedle

PRECISELY!!!
The cube will never get a chance to dry out, and the plant will develop root rot!

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Let me repeat myself....the cube is NOT SUPPOSED TO DRY OUT!!! It doesn't need to - not in a DWC, anyway. Air is circulated through the reservoir with one or more air stones, disolving oxygen into the nutrient solution. The plants get all the oxygen then need from the solution.

And being wet isn't what causes root rot in a DWC system either. Usually root rot in a DWC is caused by res temps that are too warm; insufficient air flow into the res; or roots that grow too thick and restrict water circulation. Failure to completely clean your system between grows can also cause root rot as well as other diseases. But not letting your rockwool dry won't do it.

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Originally Posted by Help_Needed

Let me repeat myself....the cube is NOT SUPPOSED TO DRY OUT!!! It doesn't need to - not in a DWC, anyway. Air is circulated through the reservoir with one or more air stones, disolving oxygen into the nutrient solution. The plants get all the oxygen then need from the solution.

And being wet isn't what causes root rot in a DWC system either. Usually root rot in a DWC is caused by res temps that are too warm; insufficient air flow into the res; or roots that grow too thick and restrict water circulation. Failure to completely clean your system between grows can also cause root rot as well as other diseases. But not letting your rockwool dry won't do it.

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Well, maybe I used the wrong term, 'dry out'. I didn't mean to turn it completely dry. If a plant is in a 5" cube with very little or no roots coming out yet and is constantly sitting in a bucket or a tray with the bottom inch of the cube emersed it cannot thrive whether there are clay pellets around it or not. The constant water will prevent oxygen from reaching the plant.

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Originally Posted by SpaceNeedle

The constant water will prevent oxygen from reaching the plant.

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Dude, you're still not getting it. In a DWC system, the oxygen is IN THE WATER. The water carries the oxygen to the plants. That's why you use the air stones, to create a high level of dissolved oxygen IN the water. Root contact with the air is completely unnecessary in a DWC environment. The entire root system of the plant can be completely submerged throughout the entire grow with no ill effects as long as you're pumping enough air into your reservoir.

prop-o-gator root stimulant works great

Quote:

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Originally Posted by Help_Needed

Dude, you're still not getting it. In a DWC system, the oxygen is IN THE WATER. The water carries the oxygen to the plants. That's why you use the air stones, to create a high level of dissolved oxygen IN the water. Root contact with the air is completely unnecessary in a DWC environment. The entire root system of the plant can be completely submerged throughout the entire grow with no ill effects as long as you're pumping enough air into your reservoir.

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NO, you don't get it. I'm not arguing that oxygen is carried thru the water in a DWC system. I've run DWC for several years. I am saying the plant will suffer when placed in a 5" square when first placed in a DWC system. By that I mean a young plant with little or no roots coming out of the bottom, and then being partially immersed in the water. The water (or nutes) will be sucked up by the cube, not enough of the oxygen. I have done experiments of taking two plants put in DWC. The first in a 6" pot with all rockwool, and the second one just filled with clay pellets only. They were grown side by side. The one with the rockwool did not do very well at all. The one in hydroton thrived. I had 4" net pots on a flood and drain system using hydroton as a media, and discovered the plants that were rooted in rockwool did not do as well as those that had no rockwool because they were rooted in an aero cloner. This was simply because the water schedule was once every 4 hours which was too much for those that had an inch of rockwool around them. A small cube would probably be ok in a DWC, although it is NOT helping the plant any in its younger days. After a while I've found the roots just develop above the cube and then thrive.
The placement of a plant into flowering is pretty stressful the first few days. That's why we keep the light further away the first day or two. If you want to give your plant a good start, don't put a small plant in a 5" cube in a DWC and expect it to thrive.