I really don't think they turned brown and lost root hairs because of nutrients, considering that plants with roots that big must also have substantial mass on top ( but really we need to see how big and know how old the plants are ) yet aero is pretty amazing in terms of root size vs leaf mass. Do you have sprayheads on both sides of this reservoir? I ask because it looks like roots nearest to the sprayheads on this picture are brown, but the ones further away aren't. The closer brown ones are also fish boning a lot so you probably have the spray on time set for too long, or the off time too short.

This post was edited by ethnobotany on Sun, Mar 17, 13 at 13:54

the plants are about 3 weeks old from first seed germinated. there are 4 nozzles in each bed. 2 on each side. bed size is 2'x4'x10" ( there are 2 beds). Regarding the browning comment there were more roots on the other side but they have died off almost over night.
water temp: 69f
on time: 20 sec
off time 25 min
water psi: 110

other side of the same bed

The plants are looking good above the reservoir at least.

OK so the problem in my opinion is that your off time cycle of 25 minutes is way to long. Now that the plants are getting bigger they need more water, so while the long off times were ok when the plants were still small (like the ones that still have white roots), the larger plants need to be watered more often.

A good timing cycle for aeroponics is 3-5 minutes off, 1-5 seconds on. Since you have a large reservoir with few misters I would go for 5 minutes off, 5 seconds on.

I agree that reducing the off time would be a good idea to try.

Your reservoir water temp is great. Is the air temperature inside the root chamber that low? I'm guessing it probably isn't, and a more frequent misting could benefit you by lowering root zone temperature even if the roots still seem wet after 25 minutes. I think that's what makes aeroponics so challenging; roots hanging in air will fluctuate in temperature much more than roots in any type of media.

I've adjusted the timer to 5m(off),5s(on). i hope this works : ). my reservoir is actually really small only about 2.5 gallons. it's separate from the grow chambers. i have air stones,circulation pump and a temp regulated heater. temps are good now because were still at the end of winter here. i'm guessing temps will rise to the 72-76 range in the summer as the room temp will be slightly higher.i will check chamber temps tomorrow when lights are on and report back. i actually just bought a humidity sensor that will throw a exhaust fan contactor when the humidity rises above a certain level. surprisingly cheap (30$) just amazon search humidity sensor.
thanks for the advise any more would be greatly appreciated sense this is my first grow with this system. i'm thinking about purchasing the 3 part general hydro nuts.

This post was edited by growyourown1 on Sun, Mar 17, 13 at 22:55

close up of some roots : )

Kale 6 days.
So I've switched my nutrient solution to general hydroponics 3 part. it's been in action for the past 4 days!. 5ml per gallon of "micro" and "grow". which is coming out to about 600-700ppm. Mist cycle is 15s on/10min off. Temp has been stable at 69f. Ph 6.3-7.0. light 12on/12off. I've purchased some more parts and plan to incorporate some more misters. 8 Misters per grow bed (2'x4'x10"). I've been trying to come up with a cost effective way to make a small water chiller for in the summer months when my reservoir temps will climb...

any advise or constructive criticism about the setup is welcome

This post was edited by growyourown1 on Wed, Mar 27, 13 at 13:53

A 20ft coil of 1/2" hose in an picnic/igloo coolbox is a cheap option. I use a thermostat to open a solenoid valve connected to the cold water supply. Cold water fills the coolbox from the bottom up and the warmer water exits via an overflow at the top. The accumulator lives in a cool brick shed so the nutes stay fairly cool and no heated nutes return from the chamber (drain to waste).
If you have a large flowrate like low pressure aero you`ll need a lot more hose to increase the contact time.

Brown roots in hp aero is usually a sign they`ve been too dry, too warm or both.

This post was edited by hex2006 on Wed, Mar 27, 13 at 16:58

roots update

beans,kale

ROOT UPDATE are these roots looking good?

2 days worth of growth. the picture on the left is the most recent pic (4/5/13 - 4/7/13)

This post was edited by growyourown1 on Mon, Apr 8, 13 at 2:55

Looking good! I think those roots are awesome.

This post was edited by ethnobotany on Tue, Apr 9, 13 at 1:47