RDWC and Rookie advice

Hello all, I’m doing a basic 2 pot + tank, Return Deep Water Culture (RDWC) to dip my toes in hydroponics. I’m totally new to the whole pot farmer thing but happy to cultivate :slight_smile:

Info on setup: 2-2022 Spider Farmer SF2000 and 6” fan w/ smart controls; VIVOSUN: 4x4x6’ tent, 2’x4’ heat mat with thermostat (question on this later) and 1500w radiant heater; fans, backup heat, humidifier, DH and so on.

Currently on 3rd week of first grow - 6 Auto ChemDawgs from Weed-Seeds. Not going to get into a-lot but I started with 16 seeds, actually germinated about 11 in Jiffy pots and subsequently Broke a couple, killed a couple doing stupid shit and F’d one up so bad it has one leaf with some shoots sticking up… keep in mind, I loved and tried my best with each one. But, I have gotten this far without any support, so I educated myself on the web and went through with a trial and error approach. Since I have learned many things, added lots of environmental controls and went big with the lights.

I want to take another shot at propagation and hopefully grow some sweet medicine with a support group to bounce ideas with.

So imma take the surviving 4 ChemDawgs and add 2x Auto Ak-47 and 2 auto Super Lemon Haze. Imma do one of each in Modified subcool’s soil and other 2 in a DIY RDWC system that I plan on building over the next few days.

(Me rambling) It’s like I have good equipment, seeds, controlled environment and time to tend over them for the full cycle. What I don’t have is fellow cultivators to share with (this is my first forum ever and I hope y’all will help with this new run and RDWC build experiment.

I will add specifics on build and photos later but I gotta bounce now. Thanks


I’m new into rdwc as well starting my second grow now.

You need a good nutrient line, I recommend jacks 321

Hydro is super important to maintain good pH, ppm/EC, and water temps, good air supply as well.

Sounds like you are on the path to getting started.

Do you have any specific questions?

I do, why do you need heat mat and heater? Your lights will probably provide enough heat in the tent.

Using it for germination/seedlings?

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So a few things to do in hydro:

First, rez temp needs to be below 70F. You will almost certainly need a chiller.

Second: how much air going into buckets?

Third: what nutrient line?

Fourth: make sure liquid level in buckets remains 1 1/2 to 2" below net pot.

Fifth: lights are enough for veg but insufficient to properly flower out plants. You will likely need double what you have.

Sixth: what instruments do you have for measuring PH and TDS? Very important.


Thx, I’m going to use General Hydroponics Nutes https://edge.generalhydroponics.com/www/uploads/20210121184307/FloraSeries-Custom-Feed-Charts.pdf

Here’s how it started: I bought a 5 gal DWC system - bucket, pump, net lid and media and set off educating myself with hydroponics and found out water temps and available O2 is critical for success. Single bucket :bucket: n 78F room will not work… So my basement floor and walls stay at 56f why not circulate the fluid and use the surrounding concrete to cool water.

NOTE: once RDWC is built I will let run alone and make adjustments to cool the solution to the best temp possible. I hear that’s around 68f … I think cooler is acceptable but not sure on solution target temp and limitations (any input?)

Nutrient height from pot… what is the optimum level? And is it useful to be able to raise/lower water level throughout growth?

Again: ideal solution temp and limits?

W/RDWC do I dump solution or can I monitor PPM/PH and simply add to solution that is cool and aerated


I set my cooler to 68, so it turns on at 68 and cools to 66 maintains a constant 66-68f of my nutrient solution.

Through the winter I’m on a slab, the chiller turned on a couple/few times a day, I’m imagining it will get more use summer time.

If I remember correctly 70f and above is danger zone

It is best to keep the water level consistent, you may have it a little higher in seedling phase before roots teach water to help the plants get started but once roots are formed you want inch and a half to 3 inches between bottom of net pot and water,

Seedling stage I keep my water close to the net pot bottom about an inch away, the air stones blowing bubbles causes spray to hit the hydroton so I don’t have to do much of anything through seedling stage.

Some hydro growers will top water the plant to help seedlings access water before roots are formed and reaching solution.

So once your plants/system is up and going you will be mixing nutrients outside of the system and adding them in. So you need to know your systems pH and ppm/EC

Then you mix up your new nutrient water to fix/adjust whatever is happening in your system is that makes sense.

If my pH starts drifting low then I will pH my mix water a little high to balance it, if the plants are drinking more water than nutrients and my ppm/EC is going up in my system then I might just add pH water and no nutrients next time.

If my ppm/EC starts getting low I can mix more nutrients to bring it back up.

I hope this helps.


I’ve tried this without a chiller. I don’t think it’s possible to both have enough light AND cool enough nutes without some sort of cooling.

As to the rookie part, @SwamiBrownEye , may I suggest you look at my grow just completed:

and some other thoughts about my setup, start here but the whole thread may be worth reading.

Good luck! Lots of helpful folks here, ask questions get answers!!

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Do you think he would need more than two of those lights?

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400 watts in a 4 X 4 is just about half needed for flower.


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I checked out the PAR maps on this light and is pretty good for a 2 x3 area, so If you had two you would be good for a 4x3 area. So in your tent you left room on the sides for a humidifier and dehumidifier it would be good.

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Absolutely helpful and thanks for the sound advise! Thinking I’ll get things set up, stabilized, add the correct amount of nutes for week 1, EC that mix for a baseline and adjust from there.

Water levels seem pretty straightforward.


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Awesome, that’s totally where I’m at.

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Thx, one sf1000 is good for a 2 x 4 space so thinking 2-sf2000 would be good for 4 by 4’. That’s what I’m finding w/some research on the light.


So. It’s like 245gpm pond pump from harbor freight. Only like $25.


@OldSkunk @Graysin @GreggT @Fieldofdreams @Myfriendis410 @kaptain3d well the flex seal tape didnt stop the drips so it looks like im going to have to cyt off the 2 shutoffs in the photos and repipe them also is anyone familar with the quick connect in the photo on how best to use them . This going to push me back a week


That middle nut unscrews

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Where exactly is the leak?

At the x’s one the ball valves. I called him last night and I think we gotter fixed up.


@Fieldofdreams thanks for the reply the res was leaking at the bulk head union where i connected a screw in connector and same at one of the plant totes. I figured on Sunday ill tear them down but not before disconnecting at opposite side shutoffs of res and plant totes keeping ball valves on both ends connected taking to sink and filling after tightening and seeing if they still leak; if so ill just replace everything from bulk head union to other side of ball valves. If not ill eliminate the elbow after the ball vavle and use quick connectors just after the ball valves.




YESSIR!!! @robert365

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