brown roots? but not root rot!!!

have nft.canna aqua vega 1.2 cf, ph 5.8, tap water ( been tested ok ). about a week after being put in the tank the roots under rockwool block turn a sort of translucent brown and are weak, but do not go mushy, roots outside of block are white but eventually go the same. plants still take up water, but growth is very slow. stem go's purple and older leaves, then others yellow suggesting slow,or no neut up take. everything is always sterilised and rinsed, but this has happened 3 times in a row. please refer to before and after pic. can anyone PLEASE help.

what type of buckets you have them in? if they are not light proof then light gettin to the roots may cause them to die out like yours

roots are covered in nft tank

Fill out the troubleshooting form at the top of the forum. Most importantly for your problem, we need to know how you are aerating your nutrient solution, what your nutrient solution is, what the pH is, and what the temperature of your nutrient solution is.

Fill that out so we can help you.

-indoor
- hydroponic
-specific medium: rockwool block
-Soil type/brand: n/a
-Hydro
-Anything you have added to the soil:n/a
-Soil pH:n/a
-Water source: tap water/ recenly tested
-Water pH:5.8
-Age of plant: 1 month ( mother 7 months )
-Type of fertilizer: canna aqua flores
-Rate of application: have tried constant and every 3 hours
-Lighting source and distance from plant 600w son t/ 1 1/2 foot
-Temperature (both day and night if you are running a dark period) day: 30 degrees/night 20 degrees
-% Relative humidity: 50
-Lighting schedule18/6
-Type of ventilation your room has: intake from open window ( not good i know, but not my house) rotating fan and extractor.

not sure what nutrient temp is, but it is not cold.

Well, the first picture has roots that look perfect and the second picture looks like they've become desiccated. What is the white material/background in the second picture?

How do you apply your hydroponic nutrients? Does the NFT mean nutrient film technique? Your problem has to be one (or more) of the following: light contacting roots, insufficient oxygen in your nutrient solution, pH of nutrient solution, chemicals in nutrient solution, or pests.

Could you guess on the nutrient solution temperature? If it is too low it will shock the plants, too high and it will not hold the necessary oxygen.

the white material is the spreader mat, yes it is nutrient film tech. i don't think it's light because the roots go brown under the block first . roots inside block seem to be strong and healthy. been to my local hydro shop and they say that the solution should be adequately oxygenated in my system. but i have been adding liquid oxy (ie oxy plus) at 5ml per 10 litres. i also add pythoff. ph of solution is 5.8.
solution temp if i had to guess would be room temp/ tepid but not warm. when you say desiccated do you mean dry? because they don't feel dry. as i have said i have discussed my problem with my local hydro shop and they are totally stumped!!!

I'm almost out of ideas. If I had to take a guess, it would be root oxygenation. You mentioned the local hydro shop said the solution should be adequately oxygenated, how are you oxygenating it? Are you relying on falling solution to churn? or do you have a pump aerating it? You also said that you add liquid oxy, so I'm assuming thats H2O2. 5ml per 10 liters would not be enough to oxygenate your solution by itself, so I'm still leaning towards 02 supply.

Can you take us some more pictures? Some duplicates of what you already did, in better quality would help. Maybe a few of your whole setup as well.

i was relying on falling solution to churn as it entered the plant section. but know i have put a hole in the deivery tube so some of the solution falls back into the tank getting aerated then being pumped into plant section. i will also put a spare pump i have in just to aerate the water near main pump. as for pics i only have the phone cam, and only 2 plants in the system which have just rooted to the spreader mat, so i don't really want to disturb them as the roots seem to look ok at the moment. i'l see what happens over the weekend and let you know on monday.

I am curious about the spreader material too, and the NFT/rw hybrid system you are running.
Can you post pics that show the system assembled, and how it all sets together? What is the spreader mat for in your system? How does it fit in?

On one hand a RW slab holds plenty of moisture and can be fed with a slow drip, or by ebb and flow bery effectively. On the other hand, you are running towards NFT. If that slab is sitting IN the NFT channel, it will be too wet, all the time.

I've seen leach trays that seem well suited to holding a RW slab ABOVE the NFT channel so that you can start out doing drip or flood until the roots are long enough to go into the channel, and then stop dripping and go true NFT. They are shown actually in the thread 'stinkys adventures in noob hydro' in 'grow logs' under 'basic growing', which is a hybrid NFT system, and was also finicky until the root system was established.

The trick with what I think you are trying to do is finding the balance between overwatering the slab and underwatering the protruding roots.

well the last 2 clones i had have now gone the same way. thought they looked alright but checked today and roots had gone brown under the blocks. it's strange though because on the first lot that did this i pulled all the brown roots off and now there are fresh white roots appearing! so they are still trying to grow, so im assuming that the plants themselves must be alright. i was beginning to think that the mother had picked up some sort of disease ( or has she? if you know of any let me know ). i'l give them another week to grow more roots and try again. ( i will not be beaten!!!!!) posted some more pics, same quality im affraid. it's a pretty basic set up, water get's pumped from the tank up to the growing level which is on a slope and then falls back into the tank at the other end. the spreader mat simply gives the roots something to grow into.and keeps them moist when the pump is not on.

The cutout you made in the third picture, for light protection, is it very light-tight? If too much light is getting through either at the cutouts or on the perimeter, it could indeed cause the problem you are having.

I would still tell you to add an active form of aeration for your nutrient solution. My best guess on your problem is inadequate oxygenation of the roots. Fork out the $10 for a pump at wally-world and another $4 for some air stones. Put those in your reservoir and let them run 24/7.

Another thing you might try, if you have any more plants not attached to the nutrient film, is to remove one plant and set it on a plate out of the system. Water it a couple of times a day to keep the rockwool moist and see if the roots do any better.

there's two covers. there is a black one under the white one which has been cut in this way X so that each corner sits on top of the block and stops any light getting to the roots. you can just see it on the third pic. the white one is purely for reflection . i have put an extra pump in the tank which just feeds back in resovior near the main pump. it makes a lot of splashing noise though!!!!! all the plants i have taken out of the tank and stripped of brown roots are all rooting again, so next time i intend on only running the solution once or twice a day.

Try running without the spreader. My instinct says the root of the problem (har har har) lies somewhere between the block and the tray... roots will naturally grow to the best area available to them, and don't need guidance.

yea i have thought about that myself. but then i would have to run the solution more frequently to make sure the roots do not dry out.

good news i have now got an air pump for free!!! bad news is i got it from my local grow shop because they are closing down and moving abroad. shame really because they are really nice people.