I don't understand exactly what I am looking at, but you comment that those black tubes you have the plants mounted into are 2", and it looks to me like the distance between each plant center to its neighbor is only about 3".

There seems to be a small irrigation line in the image too, but how that services the roots I can't guess.

How big are the rock wool mounts, how much of the path do they obstruct before adding the growing root mass, and how smooth is the through flowrate at this point - have you noted a drop off in that? People have all kinds of creative systems, but your roots may have just reached the point of filling out their very small allotted space (can you peak?) and also wonder how much oxygen is getting to downstream even if it is still open enough, is their less wilting on the ones that receive nutrient first?

Hello,

Thank you for your reply.

I am using 1 1/2 inch cubes. There is very little space between the bottom of the cube and the black tube. Width of the system is a little more than 3'. When the 10 minute cycle is over the water drains almost instantly. There is a few air stones inside my 50L reservoir that sits underneath my system.

I can't see major difference in wilting in first or last plants.

Here is a link that might be useful:

I hope someone else can interpret this, but since it drains instantly and there are no significant differences between upstream and downstream plants, and moreover things look fairly uniform and onset was about the same time, it is hard to believe it is from the first thoughts: disease, issues with changing oxygen or nutrients since some plants would likely stand out as clues.

Sorry I'm drawing a blank on this interesting system. The only two thoughts further would be something environmental but you seem to have that controlled or the result of water used to prepare the nutrient solution being too chlorinated, but you didn't mention 'right after a nutrient change' - like just happened to me with similar even handed wilting and root damage for my plants in a different kind of system.

At this point I wonder if cutting the 10 minutes in half wouldn't work better since you say it is already very moist.

This post was edited by PupillaCharites on Wed, Nov 20, 13 at 22:53

Any fluorescent fixture will need to be very close to the plant to work optimally. Your plants could be just be needing more intense light. They don't look unhealthy, just light-starved. Air movement helps, too.

Hello,

I attached a picture of the same plant taken 2 weeks ago that has the most wilting. I believe it has a problem with roots. Since I noticed the problem I have started adding small amounts of H2O2 to the tank and it helped somewhat. Also 3 days ago I have changed how much I water them to just 1 time in the morning and 1 time in the evening since the cubes are soaked. I am guessing there will be enough nutrients in the cubes for the day and enough water and oxygen.

I don't have good air movement near the system. I will add a small fan to help air flow.

Currently my bulbs are 3.5 inches away from the plants.

Thank you both for your help. This is my 4th system I am testing. Trying to figure out what system can produce most plants in the smallest amount of space. I hope I can start a small farm next year.

-Max

Please come back when the dust clears and let us know how this thing shakes out.

IMO you are pushing the envelope on root space/plant density too far, but that challenge would be fun as you mention. Cutting back on getting too soggy is also what I would try, and maybe next time trying 1" rock wool. The root in the picture doesn't look bad but maybe just small for the amount of foliage. I'm thinking the cubes may getting pressed against the shoulder of the tube, impede flow, and only leave room for the center to grow down the tube's trough, which might explain the long ponytail type root. It is better to have more small roots than fewer long roots, since the plant has to work much harder to put everything through longer fewer root-plumbings with longer lengths. The thing about high plant density to experiment with is more plants sometimes decreases overall yield so I guess that is part of your trials.

Getting the roots down initially has been my problem too, never getting the perfect nursery set up. I wonder if in your type of system you could get a pack of toothpicks to start out and use the smaller cubes with corresponding smaller holes; I've seen plastic toothpicks somewhere like these maybe,
plastic angled toothpicks, but with your initial frequent irrigation and with the goal of providing a more oxygenated water generally in this sort of design, depending on how high the water really gets when 'on'.

I'm obsessive as they get about clean systems, but also I am against using non-specific chemical disinfectants on my own including hydrogen peroxide since they also damage healthy fine tissue, but if it helps on balance especially by releasing O2, that's great. I know others swear by good results from it as part of their strategy...

Thanks a lot for sharing. If that is conduit PVC (and not Sch 80), check with the supplier to see if it contains lead. I don't think leaching is the problem at all, but conduit has a different spec as to heavy metals and plasticizers. It does do a great job keeping out light though and holding up in Sun.

This post was edited by PupillaCharites on Thu, Nov 21, 13 at 11:22

If the rockwool is saturated, that could be a problem. I grow with 1" cubes and NFT - plenty of size for 16" tall lettuce (bibb).

I agree with what PupillaCharites says above, too.

How much nitrogen are you feeding them?

Heya Mux,

Looks like nutes are reaching toxic levels possibly or you using low quality water.
Have you an EC meter?
Check your water EC level, for lettuce it shouldnt be more than 1.2mS and with any recirculating system EC levels can increase over time with addition of nutrients.
If you dont have a meter, flush your system with rain water a few times and see if your plants recover. If they do, use rain water with a batch of freshly mixed nutes but not over the 1.2mS level.
Hope your plants aren't dead already!