Iv'e had quite a few good results using NFT, i have two 604 trays in a 2X2m grow tent with 1000w total lighting. Every previous grow has been fine with the root mass being about an inch thick and very white but the last few grows i have done there has been no roots on the spreader mat at all and the roots that have (just) come out of the 3" cubes are brown.
It looks like there drowning. this is where i have found the problems start .....

1. I use cuttings in an aeroponic propagator by placing the cuttings in the rubber ring and susspending them in the net pots.
2. when there is a nice root ball on them and very white i transfer them into a 1" cube which has been soaked in ph correct water for 24hrs then soaked in 1/4 strength rizotonic for another day and left to dry a bit (so ther not soaking)
3 . Next is where i start to get problems. I then transfer them to 3" cubes that have been similarly treated, before any roots start to show out the 3" cubes can take weeks and sometimes not at all. Anyway lets assume i start getting some nice strong root growth that is still nice and white. I transfer them to the nft trays (using all the same pump and nutes as in my good grows)

I get very little root growth and all roots brown off quickly, i have started to turn the pumps off for some time to encourage roots spread (good grows were 24/7)

I'm stumped, the only 2 things i can think of is the cubes are so wet there drowning and the temps of the nutes are way too high even tho i have my freezer working full time with water filled pop bottles to put in the nute tank.

any advice welcome here im bamboozled.

I was thinking as my roots are great and V white before using the cubes, instead of using cubes in the NFt could i use 3 or 4 " net pots and clay pebbles in the NFT trays , this would stop the roots directly near the main plant stem being too wet by what the cube would hold, or would the roots that are here actually dry out causing the plant to die..

Have you tried, taking the cutting and putting it straigh tin to a small cube, then over the aero prop, once roots are nice, transplant in to larger cubes. Just a thought...does sound bizarre though

That sounds like a good idea to try , I have done this on other grows but when the aero prop is on it does make the cube too wet again. I will have to leave the sprinklers off this way, seems to defeat the whole idea of the aero really. But maybe the way to go.

Have grodan changed the way they make the cubes or something , coz they never used to hold this much moisture before , just a thought.

not really sure mate - I have not used the aero before, but have NFT, and moving from cube to cube always worked well for me

have you always used you aero prop.....

problems seam to be that the roots that come from aero cuts are more like nice straws and not as much very fine roots happning and when you put them in cubs they
cant take hold and end up getting dead roots and your problem start there...
ive found they are great at taking cuttings and if you was growing on in bubblers or aeroponics no probs..
id try not to get to many roots if your transplanting into rockwool soon as you see a couple of tinys roots get them in 3 inch cubes with them tiny little cubes in the hole around the cutting and carry on with how you treat your cubes as normal..

not sure if its the same, but have a look at this thread, in particular post #61

click here

you could have pythium

hope you havn't

atb

I think you may have hit the jackpot here. The cuttings are definately not taking to the rockwool cubes, and when i think of it the aero prop has only been used on the failed grows. I will give it a go. thanks

@Scooby Snax. That was a good read, but i'm quite sure its not pythium now. Thanks

hope it is that buddy

would that fit in with your previous grows being ok?

have your problems started since doing your cuttings this way aeroponically?

Aye, the other times i've used the areo prop i have put the cuttings directly in a 1" cube and not turned the sprinklers on until there are some roots coming through the cubes, then transfered into 3". I think its been a combination of this change, over wet cubes and high temps. Fingers crossed anyway.

it sounds to me like your rockwool cubes maybe constantly saturated.
a way round this is to adjust your length and frequency of feeding.
and/or try and raise the 3" cubes slightly allowing a gap between the bottom of the cube and the nft tray.
ive done this in the past by inserting golf tees into the bottom of the cubes. or tile spacers. or whatever as long as they are raised slightly
good luck.

Ahaa ! Bartman that is the best idea i have heard since the invention of the wheel, I too think that the cube just seem to be soaking all the time even with just a trickle of nute from the pump. Lifting them just off the tray with golf tee's pushed into the cubes is an amazing idea, i will definately give that a try. I was thinking of using net pots and clay pebbles instead of cubes to keep the roots from soaking, but the tee's sounds like a much better option.

i to use tile spacers to raise them up and angle my tray lot more..
i thought when i read your post that they was not rooting into the 3" properly first before you put them on the table
i always make shore you have a good few roots coming out the cubes before going on the tray..