What's happening to my seedlings in RDWC

Hi all, new to growing so please be patient.
I have a 2x4 grow tent with a Mars Hydro TLS 2000 LED light with a 4 inch in line fan with carbon filter.
I’m running a two bucket RDWC and my reservoir resides outside my tent.
I have the lights running 16 hours on/8 hours off.
Running a humidifier to get the humidity in the 40 - 50% range during the day and 40% at night. Tent temperature sits around 24 C during the day and drops to 21 C at night.
I have the PH sitting around 6 and the EC .3, PPM 140.
The girls are about 1.5 weeks since I put them in rockwool. Since the girls are a White Widow Autoflower, I didn’t play around and just put the rockwool in hydro so I didn’t disturb the roots.
I think I initially fed them too much (running with the Green Planet 2 part fuel) as one seedling’s first set of leaves started drooping and turning a light green with yellow patches. I decrease the amount by half of the recommended 1st week feeding schedule. They’re doing much better now but the one girl is still looking a little yellow.
My question, should I just ride this out or should I be increasing the PPM. PPM seems to be staying constant with the PH increasing slightly each day.

This is the one I’m seeing issues with. The other lady is looking great.

Any advise is greatly appreciated!!


I’d recommend covering your Rockwool cubes, second do you have this hanging down past the net?

Meant to say roots - do you have roots hanging down from the baskets yet?

Check ph in all tubs and ppm. May be a water flow issue.

I have white plastic bags I’ve cut out to cover the rockwool. I left them off to let the rockwool to dry out a little as I’ve hear the girls don’t like wet feet… seemed to work as they’ve seemed to be taking off today. I’ve just put the covers back on.
I haven’t checked to see if there’s roots past the bucket yet. My water level is just touching the base of the bucket plus I’m top feeding.
I’ve dropped my ph to 5.8 and will let it sit for now. The PPM seems to be sitting at 141 and EC at 301.
So far things aren’t looking too bad except for the yellowing I’m seeing on the first and second set of leaves on the one lady. The other lady is smaller because she came up a couple days later than the first one but is looking great with no yellowing.

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I’ll double check that but I highly doubt that I have a water flow issue since I’m running 2" piping between my buckets.

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Ok then check pump filter.

And I only mention these because I have had the issues and these are simple solutions sometimes overlooked.

Checked this morning and I do see some roots past the bucket. I’m noticing the second lady is starting to turn a little lighter so adding a small amount of ProCal (less than 1/2 the recommended dosage). Going to see how the ladies react.

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If roots are to water you can stop top feeding.

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I checked the flow coming out of the waterfall setup I have and everything is flowing great. My PPMs are very low and keeping the PH in the 6.0 range.

Sounds good. Ph is good also.

Oh the ppm I usually have is 250 at that stage when roots finally hit.

And best to have an air grab below bottom of net pot. An inch or 2

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Can you share a picture of whole setup. I’m curious

I turned off the top feed yesterday morning and put the rest of the flow to the “waterfall” which is a 1/2 inch elbow coming into the top side of the bucket. More for waterflow. I’m adding a little ProCal to the mix to increase the PPM a little. I’m adding 10ml at a time into 15 gallons.

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If you’re seeing roots you should have some nutes in the bucket :grin::v:

Sure, got the idea off the guys from PA Hydroponics on YouTube. He’s running 3" tubing between the buckets but the cost of 3" bulkheads is unreal. I ended up using a 2" shower drain and used PVC to connect them together. Rubber tape all the connections so you have a little flex and no chance of water leaks.
Here’s what I have.

2 - 7 gallon buckets connected together with 2" show drain and ABS.

The reservoir sits outside the tent. Placed a tote under the res just incase any leaks happen. There’s a 4 inch air stone in each bucket including the res. There’s also a bottom fed water pump in the res. I have a valve to switch between feed from the tent to a drain hose for changing the water.

Here I have an 8 port manifold for top feeding each bucket. I’m running 3 lines to each bucket. I have two valves, one to the manifold and the other to a 1/2 inch line going to an elbow inside the bucket for water flow. Currently I have the line to the manifold turned off so all the water is going to the 1/2" elbow in each bucket. You can see the humidifier in the background.

This shows the elbow inside one of the buckets in the tent.


I’ve increased my ppms today to 225 and have my ph at 5.8 currently.
Not sure what you mean about an “air grab”. Do you mean the space between the bucket and the top of the water? I took out about 2 liters so the water is just below the bucket.

Water level 1 to 2 inch below bottom of net basket.
Meant to say air gap lol

Your system looks great. Nice job !!

Current culture 3 inch bulkheads are about $12 each.

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Thank you very much for all the advise! I’ll drop the water and watch them go.
I really should have done more research when looking at bulkheads. Amazon was $50 or more per bulkhead. Went to home depot and found the 2" shower drain for $4 a connector. First run so will see if I run into issues.

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The ladies have been doing great in my books. The roots are growing like crazy and I’m seeing new growth daily. My ppm is around 240 and the ph slowly increases, currently at 6.4. I’ve learned to not flip out if the leaves droop a little, they seem to bounce back. Seeing a change each day sure makes this rewarding. Still learning how to interpret ppm/ec and ph but slowly getting it.


The rockwhool is staying too wet…
Lower water level and as soon as roots hit the water , turn off the top feed…

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