Trouble getting my RDWC setup dialed in

Hi Folks,

I've been having some issues recently with my first grow in my new RDWC system.

I've grown successfully in DWC about a dozen times 10 ish years ago, took a bit of a growing break and decided to fire back up last year. Grew a successful DWC crop last winter and a nice summer outdoor crop in soil since. Then I found this site and wanted to go RDWC because I like to needlessly complicate things lol.

I built a 4 site system a couple months ago. 2'w x 4'L x 8' H grow cabinet built in my heated garage. 4 x 5 gallon buckets ( hold~2.5 gallons of water), wrapped in foil bubble wrap with 2" shower drains off the bottom gravity draining back to a 27 gal tote rez, total system volume is 35 gal. I used 1/2" pex tubing and 1/2" bulkheads to feed the recirc loop, 850gph submersible amazon cheapo pump. Tried a few different fittings in the end of the bulkheads but settled on some 1/2 x 1/4" bushings that make a nice stream of water that splashes the roots. Currently running air stones in each bucket as well as the rez for extra aeration.

I grew 4 JOTI Black candyland from seed and ended up with 2 females, hence why 2 sites are empty. Plants have been in the growing cabinet for 5 weeks. Root rot really stunted growth.

Plants grow in 6" net pot top hats with 4" rockwool cubes inside covered with hydroton and a foil backed foam light blocking disc on top. Rez temp 17C cabinet temp 22C humidity 35-50%. Humidity is a struggle, I fill my 1 gallon humidifier daily. Running Mega Crop at 650 ppm in tap water that is 200 ppm for a total of 850 ppm. Ph is solid 5.8 no fluctuations. Trying to keep the rez sterile with 15ml of plain bleach every 3 days.

I tried misting nozzles originally in the bulkheads and ended up with a nasty rez and the beginnings of root rot due to not enough circulation. This began my problems with my roots. I added the air stones at that point so my buckets and rez never get stagnant water. The roots have kept growing more numerous, but they won't descend into the water for the life of them. At first I thought it might be light leaks so I made the little foam discs to block the light. Still nothing. It's like the roots grow to their current length and just stop.

I changed the rez a couple weeks ago but in my desperation I added 15ml of superthrive not knowing it was organic, which made things worse. I'm going to do another rez change tomorrow and though I would pick your brains before I do so. Obviously no superthrive this time and I was going to cut back the Mega Crop to 500 ppm. The plants look starved likely from the impact of the initial root rot but the greenery has been recovering surprisingly well considering the state of the roots. I'm thinking of possibly picking up a bottle of beneficial bacteria and foregoing the whole sterile rez idea.

Any insight is much appreciated!

That's bizarre... The roots should be growing like crazy. Red temps of 60-65°F might be more appetizing for them.

agreed on the cutback, to me it looks like they have nitrogen toxicity.
I am also running MC. Id go even lower to like 400ppm + tap
My plants are much bigger with root balls nearly filling their 3gal buckets and they are happy at like 600ppm (700 scale) + tap.
I run Megacrop + 1/4 ml per gallon southern ag fungicide + 20C res temp. I have no input on sterile res sorry.
Once root rot gets you, it can be difficult to recover. Roots that rot do not get healthy again, the plant has to grow new ones.
The root growth you have sticking out looks fairly healthy.
If you are still concerned about rot, Id give their roots a good flush with fresh water and change the water a few times over the next few days.

Your system looks pretty solid though. The only question I have is where does your water level sit in relation to the bottom of the net pot?

The bottom of the net pot is about 2 1/2” inches above water level. The water stream hits the opposite side of the bucket and splashes the net pot. When I check the roots the net pots and roots are uniformly wet from the splashing.

The other thing that baffles me is the root structure itself. In my previous DWC grows the roots got long and had ample side branching. These ones are just little root nubs sticking down with little side branching.

I’m thinking of moving the two plants to my basement for a couple days in 5 gal buckets with air stones, basically a simple DWC set up. That would give me time to clean out the RDWC set up and run a more concentrated bleach solution through it for a day or so to nuke any remaining nastiness lingering in my system.

I think some of it is just because the hydroton is so wet in your pot. Theres enough moisture in there that the roots spread out into the pot more instead of straight down looking for water. I suppose that they could also be sort of filtering out some of the nutrient?
The roots do look like they are recovering well and the addition of the airstones was a positive move.
Overfeeding can cause nutrient lockout and slow things down even more, so i believe that + recovering from rot are your main issues here.
do your cleaning/water changes, dial the food back, and give them a few days and i think youll be ok.

Makes sense. When I culled the two males I pulled all the hydroton out of the root mass and I was amazed with the amount of roots that had grown in the hydroton. Usually in my DWC grows the roots just snake through the hydroton and into the water, these formed a super dense mat of roots within the hydroton.

I've now got the plants in 5 gal buckets with 2 air stones each and MC @400ppm. I picked up some 30% peroxide and mixed it @ 3ml/gal in the temporary DWC buckets. I drained,scrubbed and sterilized the hell out of the RDWC system and have it running with 8 ml/gal peroxide in fresh tap water for a few days.

I'll update this thread with some pics in a few days, thanks for the help!

etownpaul said:

Makes sense. When I culled the two males I pulled all the hydroton out of the root mass and I was amazed with the amount of roots that had grown in the hydroton. Usually in my DWC grows the roots just snake through the hydroton and into the water, these formed a super dense mat of roots within the hydroton.

I've now got the plants in 5 gal buckets with 2 air stones each and MC @400ppm. I picked up some 30% peroxide and mixed it @ 3ml/gal in the temporary DWC buckets. I drained,scrubbed and sterilized the hell out of the RDWC system and have it running with 8 ml/gal peroxide in fresh tap water for a few days.

I'll update this thread with some pics in a few days, thanks for the help!

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This is why I always suggest aero cloning, letting the root get quite long, then finish them through a hole in a net pot with.a piece snipped out for extra room, fed down to the stem an inch away from the bottom and filled with hydroton. You're always off to the races that way.

Airwalker16 said:

This is why I always suggest aero cloning, letting the root get quite long, then finish them through a hole in a net pot with.a piece snipped out for extra room, fed down to the stem an inch away from the bottom and filled with hydroton. You're always off to the races that way.

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Exactly this!
I did my first seedlings straight into the big netpots and struggled. After that, I started growing everything out in the cloner or a bubble bucket until the roots had a good bit of length sticking out of the netpots when transplanted. Been amazing since.

Those roots look bad,sorry.Not sure on the bleach thing but ive used enzyme komplete to cure this before.Net pot right at water level foam will work its way through the net pot and overflow out.Good luck.

Well things haven't really progressed much. I've got the clear slime/snot on the plant with the longer roots and the other plant's roots seem to have not grown much at all. I've cut off all the yellow/dead leaves that both plants had and most of the new greenery looks decent but not great.

I added some beneficial bacteria ( 15g Dr. Mary Jane dry powder) to my rez ( 400ppm MC, PH 5.9) after treating with H2O2 for a few days to kill off anything in the rez. I moved the plants to my basement for those few days in a simple DWC setup ( 3ml/gal H2O2, 300 ppm MC, PH 5.8 )and they perked up a bit. I ran 10ml/gal 30% H2O2 through my rdwc system to sterilize it while the plants were gone. I'm guessing now my problems are stemming from the roots themselves being infected with bad bacteria/algae.

I'll never run rockwool cubes in the rdwc system again, just straight aero rooted plants in hydroton like others have suggested. I'm wondering if rockwool and hydroton are holding too much moisture and causing my problems. Beginning to think I might have to cut my losses and cut these plants for clones and re start the system.

What do you guys think?

Are those brass fittings on the pex ?Are they safe for the synthetic nutes?

myke said:

Are those brass fittings on the pex ?Are they safe for the synthetic nutes?

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I think you solved my problem.

I looked up symptoms of copper toxicity and stunted growth is right at the top.
There is a fair amount of brass in my system, I honestly didn't even think twice about it. I'll swap it all out to plastic and change my rez water and hope for the best.

Thanks for the help, much obliged!

etownpaul said:

I think you solved my problem.

I looked up symptoms of copper toxicity and stunted growth is right at the top.
There is a fair amount of brass in my system, I honestly didn't even think twice about it. I'll swap it all out to plastic and change my rez water and hope for the best.

Thanks for the help, much obliged!

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very interested to see how this turns out.
Totally spaced on that one, I have read things about this happening with brass and copper fittings in hydro. I think its believed to be caused by the metal oxidizing.
good catch @myke

When I ripped out all the brass fittings they were black with oxidation on the inside. The adapter that I had screwed in to the pump inside the rez was completely black inside and out.

The plants have only been in the new improved system for 24 hrs and there is already a few long white roots that are twice as long as the existing nasty roots. I'm going to keep running peroxide every couple days to keep things sterile and see how it goes.

Your able to find plastic pex fittings?I was going to run pex for my feeds but couldn't find plastic fittings.

myke said:

Your able to find plastic pex fittings?I was going to run pex for my feeds but couldn't find plastic fittings.

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Yeah Home Depot carries plastic pex fittings here in Canada.

If you can’t find plastic pex fittings, you could use Uponor pipe and fittings. It’s actually a far better system where you expand the pipe on to the plastic fittings and then the plastic pipe’s memory shrinks it back in place. The only reason I went with pex over uponor is because I like the opaque pex with a white jacket and a black core. Uponor pipe is clear and would need to be painted.

Hi
Seems like your roots get air prunned (dry out when out of the netpot).
You can also see it in some photos, a new fresh white root is trying to reach the water and probably will dry later on.
Is your water level much below the net pot?

Also in the last posts, seems like you getting root rot inside the netpot root mass.
I would keep on hand feeding them from the top, once/twice per day with beneficial bacteria and your regular nute mix.
And raise maybe the waterlevel closer to the end of the net pots if its low

Crowmax said:

Hi
Seems like your roots get air prunned (dry out when out of the netpot).
You can also see it in some photos, a new fresh white root is trying to reach the water and probably will dry later on.
Is your water level much below the net pot?

Also in the last posts, seems like you getting root rot inside the netpot root mass.
I would keep on hand feeding them from the top, once/twice per day with beneficial bacteria and your regular nute mix.
And raise maybe the waterlevel closer to the end of the net pots if its low

Click to expand...

I agree looks like air prunned.

Crowmax said:

Hi
Seems like your roots get air prunned (dry out when out of the netpot).
You can also see it in some photos, a new fresh white root is trying to reach the water and probably will dry later on.
Is your water level much below the net pot?

Also in the last posts, seems like you getting root rot inside the netpot root mass.
I would keep on hand feeding them from the top, once/twice per day with beneficial bacteria and your regular nute mix.
And raise maybe the waterlevel closer to the end of the net pots if its low

Click to expand...

You might be partially right on the air pruning, my water level is around 2.5” below the net pot. The net pot and all the hanging roots have always been wet from the splashing, but perhaps not wet enough. When I did regular DWC I would start the water level 1/2” under the pot and gradually lower it as the roots progressed. I can’t do that with this system since my external res is a set height. In the future I will make sure I have roots that drop into the water before putting plants in this system. I don’t have the time to be hand watering twice a day, hence why I tried to make a more maintenance free system.

I’ve been treating the system with 2.5ml/gal H2O2 every 2 days and dunking the entire net pot up to the stem in the res shortly after doing so to kill off the root rot in the rock wool hydroton layer. All signs of slime and rot are gone now. The existing roots haven’t changed much but there are vigorous new white roots descending from the net pots. The plant with the smaller roots (blue bucket) now has 8-10 long white roots that have hit the water, it’s nice and green and starting to gain steam. The other plant (orange bucket) with more developed roots is struggling, it’s only got 2-3 long white roots and they haven’t yet hit the water. Either way things look far better now that I got rid of the brass.