Slow/stunted growth. First dwc

Hi, so this is my first dwc grow and post. I'm having problems and after multiple googles and thread searches i cannot find the answer to the lack of growth im experiencing.

Let me start by giving you an equipment list.

1.5×1.5×2.3m secret jardin
600w MH + air cooled hood
490m3 inline fan + filter
3600lph air pump with adjustable flow
50L drums/6inch net pots
Humidifier
GH flora series
Ph / ec readers
Jack Flash fem from sensi sb

I'm 3 weeks now from germination all 5 were very quick and successful.
I put into root riot cubes under t5s and let them grow a bit and get some roots before moving over to the big pots under MH
No nutes used.. water ph'd
After 3 weeks growth has been ridiculously slow. No plant is over 4 inch.. the larger one has extremely short internodal spacing going into its 6/7 set of leaves..
The others havent even got to that stage yet.
Started using nutes the other day as leaves were yellowing bottom up.
Seemed to perk up but no growth spurt..
Ph has been maintained at 5.5-6.3 max
Res temps between 18 and 21 degrees c.
ppm is 350.. only used quarter nute strength
Lights kept at a distance 24/36inch even though aircooled.. hoping they stretch a little
And temps rh have been around 25.. and 50%
No light leaks.. tents not great but the room its in is.
Im puzzled to know what the problem is.
Im not using ro water.. im in a hard water area and bought hardwater nutes..
I was using a cal/mag foliar spray at lights out before adding res nutes.

Whats peoples thoughts on this.. cheers

Your water is probably too warm and it's giving you problems. Single site buckets are a pain in the Ass. Connect them all together and use waterfalls to aerate. Lose the air pump, line, and stones.
Really helps to have it down to a solid steady 66-68*F.
My best guess though, is that you're not starting from a clean slate of RO.
But honestly, they look fine. Just slow going. Let's see the roots?

The light is too high. Spectrum is preventing stretch. Could be a few degrees warmer. I agree with above; air stones are going to cause problems. Is nutrient strength sufficient?

P s., move that fan to the outside of your tent bro. There's no reason to have it right there. Lol. As long as you're ducting is fairly new and has no holes.

I'm going to suspect water temp as well with likely some root issues get it down to 70F if you can, preferably 68. Humidity could be a bit higher and there is some heat stress so back the light off, that's way to much for them at this stage . Stop using cal-mag foliar if you have hard water (no need). What ppm is your source water at? I don't see signs of a lockout yet but its obviously not feeding much and when that gets corrected its possible you will see deficiencies caused by a nutrient lockout depending how hard you water actually is. Lets see a pic of the roots

ttystikk said:

The light is too high. Spectrum is preventing stretch. Could be a few degrees warmer. I agree with above; air stones are going to cause problems. Is nutrient strength sufficient?

Click to expand...

How are air stones going to cause problems?

Thanks for the replies..

It's been 10+ years since my last soil grow.. so this is trial and error with the jack flash.. I have some NL5xHaze seeds germinating to fish out a couple of good mothers. As apparently flowering nl5 from rooted clones is the way forward.

I have the fan inside attached to a filter and using it to push the air through into the roofspace. Plus was hoping to reduce noise.

The res temps are 68-70F
That's roughly 18-21c
Altho there really isn't much root porn in the pics! They spiral down 2ft to the bottom of the barrel.
So perhaps RO water is really needed.
The water out the tap untreated is 270ppm

My readings are 350ppm.. 700ec on the stick I use

(I've read I could use an aquarium conditioner for metals and chloramines in the water??,, thoughts?)

As for the leaf curling.. temps breached 30 degrees one day. due to an error setting a timer on the fan.. so that is my fault. The leaves weren't curling before.. that's a new ailment.

I'm unsure if nute strength is correct.. I thought I'd start of slow as recommended from what I've read.
And I also, am unsure how airstones will cause problems..
A link to these waterfalls set ups would be great.. as I've never heard of them..
Cheers guys

270ppm out of the tap is high.

I would recommend doing 3/4 RO 1/4 Tap and bump the nutes up a bit. Stop the cal-mag foliar unless you see a deficiency. More often than not you create problems by throwing extra stuff at them.

Yes seachem prime will break down chloramines. i think a cap/50 gal. I use it in mine because i use tap water with chloramines and i prefer to keep bacteria alive. If your using lots use seachem safe

Looks like you need to lower your water level in the bucket to 1 inch or so below the net basket

Axion42 said:

Looks like you need to lower your water level in the bucket to 1 inch or so below the net basket

Click to expand...

wow i didn't even notice that... good call!!!!

I got about 50 DWC grows under my belt using RO water only in RubberMaid tubs.

I'd switch to RO and your ppm is too low for plants at that stage of growth. Should be at least 500ppm of nutes so 500 plus your 270 tap water is 770 or thereabouts. With RO you don't have to think about crap like chloramine, alkalinity and all sorts of minerals in the tap water screwing up your plants.

Airstones work great. Setting up waterfalls probably works OK but I aim for simplicity and adding pumps to move water adds more complexity for screwups.

I take it you are venting into your attic? DON'T!!! Every liter of water you are giving to your plants ends up in your attic. Serious mold problems will result and if it's an unheated attic it'll freeze up there during the winter and make it rain in your house come springtime. Ask me how I know.

You can snip off the long, stringy roots and that will make the portions above branch out more. As said above keep water level an inch below the bottom of the pots. Spray from popping bubbles will keep everything plenty wet under the lid.

The tubs have two long grooves in bottom that 12" airstones lay in nicely and I've had as many as 16 plants in one tub and a s few as one doing DWC ScroG.


With RO water I've done many grows without ever changing the water. I just check the ppm and add more as the plants eat it. I use the AN pH Perfect 3-part nutes, Big Bud for a flower booster and a bit of Rhino Skin for silica. Any old CalMag will do and Epsom Salts are cheap. I never check pH and have never ran into pH problems. Before AN went pH Perfect I would check pH and it always went up to 6.3 or so and a few drops of conc. sulfuric acid would knock it back to 5.4 or so. Only topped up with RO every 3 days and that pH movement is good for the plants.

Getting into soil/organic growing these days but will be doing DWC again.

Good luck and good growing!

I've run similar setups like that for the past 3 years. Everything your doing is essentially the same conditions I used. Aside from a bit too much water in your barrel, they look like they were a bit hungry. I always begin to feed them after the second set of leaves pop and adjust to what the plant wants. I believe that you'll have a tent full of flower in no time.

Aqua Man said:

How are air stones going to cause problems?

Click to expand...

They aren't very efficient and in my experience they let to root root issues if water temperature wasn't actively managed. That's why I like my waterfalls so much; water temperature could be as high as 77F/25C and I never, ever had root issues.

ttystikk said:

They aren't very efficient and in my experience they let to root root issues if water temperature wasn't actively managed. That's why I like my waterfalls so much; water temperature could be as high as 77F/25C and I never, ever had root issues.

Click to expand...

Sorry but that makes 0 sense. Waterfall or air stone you can get root rot...neither create or solve the issue if they are supplying enough agitation to create gas exchange. How are they less efficient? i don;t mean marginal or negligible amounts. If you want to debate this we can but you will be sorry. You do know water temp is directly related to the amount of DO right?

First post of this nature... stop blowing smoke up my ass. Save it for the others.

Aqua Man said:

Sorry but that makes 0 sense. Waterfall or air stone you can get root rot...neither create or solve the issue if they are supplying enough agitation to create gas exchange. How are they less efficient? i don;t mean marginal or negligible amounts. If you want to debate this we can but you will be sorry. You do know water temp is directly related to the amount of DO right?

First post of this nature... stop blowing smoke up my ass. Save it for the others.

Click to expand...

LMAO, buddy I wouldn't steer you wrong and ask around; I've been doing this for a lot longer than most.

The reason why it makes such a big difference is because of factors that aren't immediately obvious when comparing waterfalls vs air stones.

First, air stones push hot air into the water and oxygenate by blowing bubbles. This tends to lead to constant inoculation of the water with whatever is floating around and it warms the water over time.

By contrast, waterfalls don't push air and contaminants into the water. In addition, they encourage a bit of natural evaporation which tends to reduce water temperatures.

Second, air stones don't agitate or churn the water column much. Waterfalls do. This is important for ensuring adequate water flow through and around the roots, eliminating stagnant spots and maximizing nutrient delivery.

Finally and most importantly, waterfalls break surface tension and actively discourage any films that might develop on the surface of the water in the tubsite. Air stones don't do this and again, it's a critical feature in terms of disrupting the conditions that encourage pythium, algae etc to grow.

In fact, I've even deliberately poured rotten water- stagnant water that had been sitting with dead roots and had gone bad- directly into my RDWC. Absolutely nothing happened, period.

I respect your questions and I know there's a lot of bullshit out there when talking about growing weed. I've extensively tested a lot of different methods of oxygenating RDWC grows and I wouldn't steer you wrong, brother.

The best part? No grinding air pump to buy, put up with, maintain, repair or worry about. No airlines to trip over, no gooey stones to replace. Waterfalls are simpler, cheaper, far more fault tolerant and robust- and they sound lovely.

ttystikk said:

LMAO, buddy I wouldn't steer you wrong and ask around; I've been doing this for a lot longer than most.

The reason why it makes such a big difference is because of factors that aren't immediately obvious when comparing waterfalls vs air stones.

First, air stones push hot air into the water and oxygenate by blowing bubbles. This tends to lead to constant inoculation of the water with whatever is floating around and it warms the water over time.

By contrast, waterfalls don't push air and contaminants into the water. In addition, they encourage a bit of natural evaporation which tends to reduce water temperatures.

Second, air stones don't agitate or churn the water column much. Waterfalls do. This is important for ensuring adequate water flow through and around the roots, eliminating stagnant spots and maximizing nutrient delivery.

Finally and most importantly, waterfalls break surface tension and actively discourage any films that might develop on the surface of the water in the tubsite. Air stones don't do this and again, it's a critical feature in terms of disrupting the conditions that encourage pythium, algae etc to grow.

In fact, I've even deliberately poured rotten water- stagnant water that had been sitting with dead roots and had gone bad- directly into my RDWC. Absolutely nothing happened, period.

I respect your questions and I know there's a lot of bullshit out there when talking about growing weed. I've extensively tested a lot of different methods of oxygenating RDWC grows and I wouldn't steer you wrong, brother.

The best part? No grinding air pump to buy, put up with, maintain, repair or worry about. No airlines to trip over, no gooey stones to replace. Waterfalls are simpler, cheaper, far more fault tolerant and robust- and they sound lovely.

Click to expand...

Glad to see you back around tty

Axion42 said:

Glad to see you back around tty

Click to expand...

Thanks, man! Hope all's well in your world?

Getting ready to start that waterfall run you helped me out with

Axion42 said:

Getting ready to start that waterfall run you helped me out with

Click to expand...

Hit me up with any questions, brother- better yet, send me a link to your thread!

Thanks very much for the responses!..

Will definitely look up seacham water conditioner..budget now doesn't allow a proper RO filter.. I use stress coat in my fish tank.. not sure if anything else is added tho. So seacham it is.
I'm assuming cal mag will then be needed after usage.

It is vented into the attic yes.. straight out the tiles as the room the tents in, is a dormer.

Ok. So the plan is to up the nutes slightly, and treat the water when I can!
Hopefully give the plants a kick....