A few things spring to mind.

1) Your roots have been discoloured by the nutrients, have they done this before over the course, adding a little colour each time?
2) Your nutrients are the problem. Mix up a small batch in a different container and check if it goes cloudy.
3) You have a fungal infection, possible pythium! Pythium exists everywhere in a plants environment - it's just waiting for some good conditions to jump out and cause havoc.
If you look at the roots, they will turn light brown, then dark brown and finally black. The roots will become slimy, soft and fall apart.

You can keep pythium at bay by having, amongst other things, good aeration. But, you look to be aerating your solution so your doing this OK. There are several products on the market that will help fight this, a quick google will bring them up.

That's my guess, but others may have some more ideas.

could just be algae growth. dump in some h202 and see if the water clears up. if it does, try either painting your reservoir or putting a layer or two of black plastic over it to block out the light.

I had the same problem a few weeks ago. I thought it was too much nutrient since I didn't have an EC meter. I got an EC meter and it happened again even though all levels were perfect. Your roots will recover or grow new ones pretty fast. I'm now thinking it was chlorine in my tap water or possibly due to my water being so cold from the tap and shocking the roots. I'm now leaving water in an open 5 gallon bucket for a few days with an airstone before dumping into my tank. I'm curious if you went straight from the tap?

Here's my old thread with some good info:
http://forums.gardenweb.com/forums/load/hydro/msg0210171225984.html?6

Sorry for not responding earlier, I checked the nearest hydroponic store for hydrogen peroxide but apparently they do not carry it anymore. One of the plants started drooping pretty heavily, so I assume it's roots are dead. The other plants appear to be doing fine besides having brown roots. Some of the roots have gone a darker brown so root fungus appears to be the issue.

I used tap water that I kept around 65-70F but I only waited 30 minutes before switching the plants over. In the future I will keep the tap water out for a few days with an air stone before putting the plants in it.

While I was at the hydro store I picked up a bottle of FloraShield. It cleared up the reservoir greatly and appears to have helped the plants some. I understand that this can't fix current root rot, so I was wondering what would be the best thing to encourage new root growth?

Thanks for all of the suggestions!

"Sorry for not responding earlier, I checked the nearest hydroponic store for hydrogen peroxide but apparently they do not carry it anymore."

What's wrong with ordinary grocery store peroxide?

"Some of the roots have gone a darker brown so root fungus appears to be the issue."

Well, at least in soil, that means not enough air reaching the roots (generally caused by water-logged soil). You're doing DWC, so that definitely seems like a risk.

I understand that this can't fix current root rot, so I was wondering what would be the best thing to encourage new root growth?

Again, at least on land, they'll do it on their own, so long as they don't die. It's that latter part that's tricky. If I were in your situation, I'd cut back on their light and do what I could keep the relative humidity high; plants that die of root rot are really dying of thirst.

I have heard that regular grocery store peroxide has stabilisers that are toxic to plants. That's why I intended to buy food grade 35% hydrogen peroxide but this is apparently no longer produced anymore (what the store owner told me).
I have the lights on a timer currently set at 15 hrs. I will reduce this a little and see if this helps the Bell Pepper at all (large leaves coming close to wilting).

if you don't have a chemical supplier near buy, go to your local pharmacy (not the box brands) typically a mutual member and ask them to order some for you. BTW, I've used regular 3% H2O2 before and it didn't kill my plants.

Let me share something I learned about hydroponics and roots. One of the thing about growers is we like to peek. We're constantly lifting the top off the system displacing the roots. Aeration can be your problem. See when you get a good flow of air in the water your pots are sitting in. A tangle of very hairy roots starts to grow. Now the problem here is like you see in the picture when taken out of the water the roots stck together like a loose rope. But and this is the interesting part is when you put it back in it doesen't unwrap. Now the roots aren't in the same spot they were under the pot. Now those very same roots aren't under the exact spot they were with the bubbles underneath. Those very thin hair like roots start to die because they aren't getting the same amount of air. Pythium. Now if I may make a point. You fix this problem by lowering the height of your water. These systems work best when the roots are sprayed by the water than sitting in it.

to anyone who has brown roots after a nutrient change like i have experienced for a few years - my personal experience is that when you change nutes, do 24 hours with just water, then next 24 hours at half feed and then 48 hours later up it to the right level..i was getting brown roots all the time, then through process of elimination i went bit by bit - havenâÂÂt had a brown root since :) i think its because we make it to the strength it was when we changed but were adding fresh nutes and it pickles the roots hence the brown ugly stuff the following day - probably shock with the freshness of the nutes - anyway hope this helps other folk who go sick when peaking and there heart sinks

Nevertheless, roots turning to brown after a simple nutrient change is not commonly experienced by most people - and thus no actual need to proceed like described in case. If using and also keeping an appropriate nutrient concentration (with a balanced nutrient), there is no such thing as a "shock with the freshness of nutrients" supposed to happen, - because there simply is no major change taking place. I have never experienced, nor do I know- or have heard of such direct correlation, anyway.

I'd thus look further into it and investigate the actual reason more deeply.

well you could be right that there is no scientific fact, i just gave up trying to find the root cause (excuse the pun) . i have over 12 months changed everything from buckets, pumps, left water for 24 hours, nutrient brand, sterilized from top to bottom - even changed location of growing area all to no avail, then trying to find which part caused it i gradually added each part & found this didnt give me the slimy dark brown roots i was getting every time i changed tank ...wierd but this has for the last 6 months been the way i have stopped getting brown roots

Try this;
Three days before nutrient change out, add 3.5 ML. per gallon, 6% or less Sodium Hypochlorite,Yea that's right, Clorox Bleach. It will smell like a freshly sanitized swimming pool, but worry not, it shouldn't kill your plants. I've done it many times and they rarely even show signs of shock. Your nutrient solution will get cloudier, this is simply dead root matter. Do this before every change out till roots clean up. It's also a good idea to feed the foliage with a spray bottle/nute solution while the roots are regenerating.
Good Luck,
Ken

Hello!
Guys and Gals this sounds like a bacterial / fungal imbalance in the reservoir. When you replace the nutrient water your also discarding the beneficial microbes as well. The new nutrient water encourages algae and harmful bacteria to bloom. Think of it like a fish tank. You don't want to change all the water at once because you will shock the tanks eco system, thus algae blooms and swinging PH goes rampant. Leave a little of the original water in the reservoir to help recolonize the good microbes. Every once and a while I screw up and this Root rot issue happens to me which is caused by bad microbes. I add some 3% Hydrogen peroxide to the water and let it run for 24 hours then replace the water and do the hydrogen peroxide cycle over again till I have no more brown roots. Check out General Hydroponics Subculture M and Subculture B. I use these and have good success with them. ** Add them in once all of the H2O2 has been washed out**

Personally I have never had the described problem, the original post was posted about 1 1/2 years ago. doubt if we will here from the original poster again if not by now. But although it's true that by changing the entire nutrient solution the beneficial microbes are removed, don't forget that so are the pathogens (bad ones) as well. There will be some left on the roots themselves (of both). And as far as I can tell from the original post there was no mention of ever adding any beneficial microbes in the first place, or even what type of nutrients and/or additives were used.

From the pictures The water does not look cloudy to me either, though that might be because it's just hard to see. The roots do look like they have a slight brown tint, but tinting from the nutrients themselves is normal, especially for older roots. Bottom line, I don't see anything to raise alarm from the pictures yet. It could easily just be panic from a new grower at the first singes of any change, even if it's normal. And simply without any information on type of nutrients, additives, ph adjusters, not to mention all the possible variables in how the nutrient solution was changed where something could have unintentionally been introduced into the system, any conclusions would be premature to me. And going by the original persons saying that aside from the brown roots, the plants seem to be doing fine, I would guess it was just panic over seeing a change.

There is only one thing that concerns me from the pictures, and that is that I cant' tell if the containers are light proof or not. And going by a statement by the original poster that referred to the bell peppers beginning to wilt, makes me wonder what the temperature of the nutrient solution is. High nutrient temps can cause both browning roots, and expedited pathogen and/or fungal growth in the water (causing it to be cloudy and or foamy). If they are not light proof there would likely be a lot of algae and/or fungal growth as well. However it wouldn't have been caused by a nutrient change, unless the water temp significantly rose at the same time for a different reason (like moving lights closer, or turning off fans etc.). But it's too late to ask any more questions from the original poster in order to diagnose any possible problems.

Hi Homehydro,
Several good observations: Old post. Poster doesn't specify whether or not his nutes are organic.
Oh, and jmoore3274; **H2O2 need not be washed out, the extra oxygen atoms simply evaporate**.

Hardclay!!
I did not know that about H2O2. I have always treated it as like bleach and washed everything out real well. Do you know about how long it takes for that to evaporate out of the system? Would that also be the reason why it foams when put on cuts as an antiseptic? It releases O2?

Hi Jmoore3274,
It depends on the concentration, temperature, and aeration, but I think it's safe to say It's gone in two hours or less. I am not a chemist and I can't explain the reaction that takes place when H2O2 is applied to a wound but hydrogen peroxide is an oxidizer and I think It's safe to say that it is oxygen being released which is why its important to keep H2O2 capped to keep it at strength. If I'm wrong I am sure I will be corrected.
Good Luck,
Ken

When diluted in water the H2O starts to dissipate/evaporate from the get go. But is said to completely dissipate anywhere from a couple of days to about a week. How fast though surly depends on how much you use, and water temp I'm sure. I have never tested the dissolved oxygen levels before and after using it myself (I don't have a meter). But I regularly add it to my nutrient solutions at a rate of about one tsp (5mL) per gallon, once a week when I remember. I have used twice that (2 tsp per gallon) at times though, even though it wasn't really recommended, and cant say I ever saw any negative effects.

I add it mostly for the added oxygen, but it does help keep the growth of pathogens down. On the downside, it doesn't know the difference between beneficials or pathogens. But I don't add beneficials, and I'm not using organic nutrients either, so I'm not worried about that part. I also clean my pumps and reservoir with each nutrient change as well (that only takes me about 10-15 minutes), and I haven't had an issue with things growing in my nutrients unless it was heat related. Well except one time that's a long story. It turned out that the plants (peas) themselves were secreting a chemical into the water. Peas as well as all legume are known for:

"Legume plants are notable for their ability to fix atmospheric nitrogen, thanks to a mutualistic symbiotic relationship with bacteria (rhizobia) found in root nodules of these plants."

Legume plants also secrete a chemical and/or bacteria to fend off roots from other plants. I had two types of peas in the same system growing in a tube where all the roots were intertwined. The bigger the plants got the more their roots were contacting and intertwining with other roots. That was the only time I couldn't relate something growing in my nutrients to high water temps (and/or light).

hardclay7a
That sounds interesting, 3.5 mL of Clorox bleach just before you change the nutrients. That's one I will try to remember and test out.

Earlier statement says "H2O starts to dissipate/evaporate" that's suppose to be "H2O2", you cant edit your posts once they are posted in this forum, sorry for the typo.

Homehydro,
Thanks for the H2O2 details, didn't even notice the error. I can't take credit for the clorox idea, its something I learned from Danielfp from his article "Disinfecting your hydroponic solution with Hypochlorite" He recommended 1ml per liter of 5.25% Hypochlorite Bleach. The brand of bleach on my shelf was 6% Hypochlorite so I simply rounded off some numbers, and cut it back a bit, My reservoirs are marked in gallons, so I figured 3.5Ml per gallon would be safe. You could probably tweak it a little stronger. I have used it at 38Ml. per 10 gallon reservoir without any signs of shock, But I figured why push it? I use 3.5 of 6% per Gal. and it works. When I run out of bleach and if I happen to end up with 5.25% Hypo. I'll bump it up to the 1ml per liter formula. I find those Legumes interesting, you didn't have to add anything special? Inoculant or anything? The Rhizobia just form by itself? I remember Eco Enterprises tried to sell us on minute micro traces of cobalt that they claimed were necessary for all good plant health and it ended up only pertaining to Rhizobia.
Thanks again,
Ken

hardclay7a
I will check out that article, I have been meaning to read more of Danielfp's blog. But you know how it goes, so much to do and never enough time. It was about April last spring when I had the problem with my peas. I started them in late September or early October and they grew, but slowly. I knew they were not hot weather plants, I planed to build a frame and cover it with plastic to make a greenhouse over them, but never did. So they grew and looked good, just slowly in the cold weather. But come late January early February they exploded with new growth, and wound up over 6 feet tall and 4 feet wide for 4 snow pea plants. The regular peas wound up about half that, I forget what species those were.

But to answer your question, no I never Inoculated with anything. I was using General Hydroponics Flora series nutrients and that's it, I may have used some H2O2 but don't remember. It wasn't until the plants got real big (2-3 weeks before I harvested them) that I started to notice the brown cloudy water. I e-mailed pictures and details to General hydroponics tech support, who explained that peas are legumes and that they have roots that do that. So I did some reading up on them at the time. But ya legume have roots that can change their own environments by secreting certain types chemicals and enzymes. I know I said they can secret bacteria, but I believe it was enzymes along with chemicals instead.

These secreted enzymes and chemicals have evolved to perform functions like to promote beneficial bacteria growth to help break down the soil into the nutrients they need, to repel soil born pests, and even damage or repel roots of other plant species that get in their root zone. That was all new to me before I had the problem. I wasn't familiar with growing peas either at the time, and found out that even though they had recently had a good 2 month growth spurt, they were still 7 month old plants near the end of their life. So considering that both type of peas had intertwined root systems, that were nearing the end of their life, they were just doing all they could to stay alive longer.

P.S. So I just harvested all the peas on both type of pea plants, and was able to just about fill 3, 2 gallon Ziploc bags. Most were snow peas. Witch was fine with me because I didn't want to shuck the other peas. I let my mom do that, they were here idea anyway.

I found this on wikipedia about the Decomp of H2O2. Man science is cool :-)

Decomposition

Hydrogen peroxide decomposes (disproportionates) exothermically into water and oxygen gas spontaneously:

2 H2O2 â 2 H2O + O2

This process is thermodynamically favorable. It has a Ã"Ho of âÂÂ98.2 kJ�molâÂÂ1 and a Ã"Go of âÂÂ119.2 kJ�molâÂÂ1 and a Ã"S of 70.5 J�molâÂÂ1�KâÂÂ1. The rate of decomposition is dependent on the temperature and concentration of the peroxide, as well as the pH and the presence of impurities and stabilizers. Hydrogen peroxide is incompatible with many substances that catalyse its decomposition, including most of the transition metals and their compounds. Common catalysts include manganese dioxide and silver. The same reaction is catalysed by the enzyme catalase, found in the liver, whose main function in the body is the removal of toxic byproducts of metabolism and the reduction of oxidative stress. The decomposition occurs more rapidly in alkali, so acid is often added as a stabilizer.

The liberation of oxygen and energy in the decomposition has dangerous side-effects. Spilling high concentrations of hydrogen peroxide on a flammable substance can cause an immediate fire, which is further fueled by the oxygen released by the decomposing hydrogen peroxide. High test peroxide, or HTP (also called high-strength peroxide) must be stored in a suitable,[citation needed] vented container to prevent the buildup of oxygen gas, which would otherwise lead to the eventual rupture of the container.

In the presence of certain catalysts, such as Fe2+ or Ti3+, the decomposition may take a different path, with free radicals such as HO� (hydroxyl) and HOO� being formed. A combination of H2O2 and Fe2+ is known as Fenton's reagent.

A common concentration for hydrogen peroxide is 20-volume, which means that, when 1 volume of hydrogen peroxide is decomposed, it produces 20 volumes of oxygen. A 20-volume concentration of hydrogen peroxide is equivalent to 1.667 mol/dm3 (Molar solution) or about 6%.

I don't think I mentioned this before but it's probably a important note. The H2O2 that I use and I am familiar with using is the typical 3% that you can get in most any first aid isles. They do come in stronger percentages such as 35% but that's harder to find and costs 10 times as much, plus it is dangerous if you get any on you. I get the quart size bottles at walmart for $1.06, at the grocery store for $1.35 or at the dollar store for $1.

That's the stuff I use, Germany used the high test stuff in their Me 163 Comet- a rocket powered interceptor In WWII. Many Exploded while fueling. Very corrosive, capable of burning bone as well as flesh.

Did you not look at that picture? Those roots were done for!