What's new
By:
GrowWeedEasy.com
You're browsing as a guest. Sign up to join the conversation, share your grows, and get help from thousands of fellow growers — it's free and takes less than a minute.

DWC - Help needed please!

A

axilotl

New member
Hi all,




this is my first grow and I'm having serious issues. Advice is very welcome.

DWC in 2 single buckets.




Equipment:

Tent: Secret Jardin Hydro Shoot 120 (120x120x200 cm)

Bucket: Oxypot Single DWC (max 19L)

Seeds: White Widow x Big Bud 100% (feminized) (NON autoflowering)

Water: RO (30 ppm)

pH + EC Meter: Bluelab combo meter (Calibration confirmed)

Light: Mars Hydro SP 250 (Height above plants seen in setup picture below)

Ventilation: PK 125 EC-TC (max 680 m3/h)

Light Schedule: 18/6

Nutrients: General Hydroponics Tripart

Supplement: General Hydroponics Calcium Magnesium (added beginning 3rd week)

Additional Equipment: Small fan blowing lightly towards plants







Week 1 and Week 2:

Water in Bucket: 13.5L (which is about 2 cm below bottom of netpot) (= 3.6 gal)

FloraMicro (Soft Water): 14mL (= 2.8tsp)

FloraGro: 14mL

FloraBloom: 14mL

Resulting ppm: 550ppm (1.1 EC)

pH: 5.5 to 6.5 (adjustments were made)

Temperature tent AND water: between 22 C to 25 C (71F - 77F)

Water changed after Week 1, 2nd week parameters same as above.

Issues:
  • Very slow growth
  • Plant not growing in height
  • Brown, rust like spots on leaves (not just tips)
  • Leaves curling
  • Leaves with spots dying
Week 3 (which ended today):

I thought maybe I gave too many nutrients, so I reduced those. Also thought they are lacking CalMag so added CalMag and tried to follow this:

Recirculating-Nutrient-Schedule-custom.jpg




Water in Bucket: same as above

Calcium Magnesium Supplement: 10mL (=2tsp)

FloraMicro (Soft Water): 5mL (= 1tsp)

FloraGro: 5mL

FloraBloom: 5mL

Resulting ppm: 300ppm (0.6 EC)

pH: 5.5 to 6.5 (adjustments were made)

Temperature tent AND water: between 22 C to 25 C (71F - 77F)

Additionally: Yesterday (second last day of week 3) I saw a fungus gnat on a leaf, so added yellow sticky traps, and sprayed leaves with Neem Oil

Did not find anything on the yellow traps, roots looked clean visually.


Setup:












End of Week 3 Roots:
  • No slime or smell




Close up - Problems:













Known Issue:
  • High water reservoir temperature
Troubleshooting performed:
  • Added 0.5L frozen bottles inside, however temperature barely dropped 2 degrees Celsius for a short while
    • Cannot afford Water Chiller
    • Purchased fridge, but haven't managed to make copper coils
  • Since growth is slow, I am not yet going into flowering light schedule!



Please Assist:


Please provide feedback. This is my first grow and I have no clue what's going on.
  1. Do I even need CalMag supplement when using TriPart FloraMicro specifically for soft water ?
  2. Are ppm's way too low now?
  3. Were ppm's too high in first 2 weeks?
  4. Is the lamp height acceptable ?
  5. Could the water temperature alone be causing the leaf problems and slow growth ?
  6. Suggestions ? Can this be saved?
Thanks!!
 
RO water needs cal mag from the beginning just fyi. Also ppm seems low. This mainly matters because RO water is hard to keep ph stable. My guess is ph flux but i would also add hydroguard as it allows for higher temps. I would defoliate too. those big fan leaves are blocking lower leaves and bud sites not allowing them to grow. Also, you want to keep plant short in veg cause it will stretch in flower so the plant height is not an issue. Roots look good so i dont think its root issue. Plant looks fine size wise for its age. Other than the calcium deficiency id say it looks fine. Make sure you are allowing res water to flux past 6.0 so it can uptake calcium
 
Howdy axilotl, I grow in DWC 10 gal. totes (a.k.a. Bubble phonics style). I use the GH MaxiGrow and MaxiBloom with some of the GH supplements. I use just plain tap water from the city. The water was very 'hard; as the majority was from water wells, now this year, the supply has most of it coming from a reservoir (lake) and I am going to start using the Cali Magic supplement as well.
As far as Your set up goes, move the fan as far away from the plants as possible and do not point it directly at the plants to prevent 'wind burn' (drying) of the leaves. I use ice bottles to keep the temperature down (between 62° F and 70° F), I have the reservoirs wrapped with bubble wrap (large bubbles seem to work best) to help keep the cool in and the heat out. Depending on the size of the plant canopy (more shade = less heat) I can keep the temperature down for up to 3 to 4 hours
Good luck with Your grow.
 
Roots look perfect and new growth is healthy. I've never grown hydro but I have seen leaves time out like some of your large ones seem to be doing. Like Tersky mentioned, a little defoliation of those affected leaves will benefit the overall health of your plants and promote new growth.
 
Wow thanks, you guys are awesome. I just posted and you already replied. Im gonna follow your advice and defoliate right now.
Also I will go and check for bubble wrap tomorrow. Maybe the ice will do the trick better then. Can there be a negative impact from the ice bottle directly touching the roots? It will definitely touch.
I also saw the scale for Calcium uptake. I'll try to keep the pH above 6. Its really difficult to maintain I find!
I had the fan away at first, but i've put it on very weak, the leaves barely move.
Regarding Hydroguard, it's not sold in Germany. Can't find a good alternative!
As for the brown spots and leaves dying, conclusion = CalMag ?

What are you guys recommending as per dose or ppm ?
How much CalMag?



Update:

So buckets are freshly filled, again as last time Week 3:

300ppm, pH now 6.0 and large fan leaves removed.
Fan moved far away!
 
Last edited:
As mentioned above, looks like a calcium deficiency, you can use either calmag or something like calcium nitrate since you don't appear to have a magnesium deficiency. As for the high water temps, you can either sterilize as mentioned above or use beneficial microbes if you're not going to use a water chiller.
 
I use water straight from the tap at about 180-220 ppm. pH is usually close to 10.0. After adding nutes it doesn't need much pH Down to get it in line. Our water doesn't get chlorinated like some other places do, luckily. You could try straight tap water if isn't too different from mine and see if it stops your micronutrient problems, if only on an experimental basis.
 
Unfortunately my tap water is way too hard. Around 500ppm! Definitely cannot use that as a starting point. I will look into getting an alternative to the Hydroguard.
In DWC, late Veg, how much ppm should I aim for with RO water (30ppm).
 
axilotl, I had tried using the Hydro guard before, but it did not perform like I was expecting. I have found that once ALL of the light leaks (and yes, I cover over the hydro-ton pebbles with aluminum foil!) are covered or sealed and the water temperature is kept below 70° F, the root rot will not be a problem. I have not noticed ant root damage near the ice bottles that I use to cool down the reservoir. One other thing that I forgot to mention, plastic containers need to go thru a 'curing time' before the pH levels can be stabilized. I had pH 'shifting' problems during the first two to three grows before the pH levels became normal (the levels do change as the plants take up the nutrients from the water during normal growth).
 
They should be able to handle 700-800 ppm easily (or 1.4 to 1.6 EC). For me, 800 ppm was about the heaviest feeding they could stand without showing nute burn. It depends a lot on what variety you're growing. I've got a Blueberry in late veg that can't handle more than 600 ppm. The Black Widow I just harvested took 800 ppm just fine and probably could have handled more but Bruce Banner burned past 800. I think sativas are just more nute sensitive.
 
But isn't that the reason for using FloraMicro softwater as opposed to FloraMicro hardwater? In theory I need to still supplement CalMag ?
 
pH instability issues:

So at 8AM, I pH'ed the larger plant back up to 6.1 (from an overnight drop to 4.5)

Now 9 hours later, I checked again, pH dropped to 5.1

During this period, nutrients dropped slightly from 390ppm to 360ppm. Water only dropped around 100mL.

Any ideas whats going on?!
 
It's your plants taking what they need. In mid to late flower, I always have to keep adding pH Up because of their hunger for potassium. Losing potassium from the nute solution causes the pH to drop. pH Up has potassium hydroxide as its active ingredient while pH Down has phosphoric acid. They are safe for hydro because they are also effectively micronutrient supplements. You might want to try feeding a bit heavier.

On a side note, I got Ed Rosenthal's Marijuana Grower's Handbook yesterday. According to Ed, tap water at 220 ppm is on the high side of good. All I need is to add epsom salt to boost Magnesium levels.
 
Just to clarify, low ppm levels are more susceptible to wild pH swings because there isn't as much substance in the water to help buffer the effects of nutrient uptake by your plants.
 
NEW PROBLEMS!​

Hi all,
thanks for all the support. So I extended the Veg a little bit and am now flowering since 1 week. I encountered the problem as shown in the picture below.
I am still following the nutrient schedule from my first post above. 1,1,1,1/2 (ppm around 800). Roots still look good. New growth, no rot signs.

Some of the leaves are getting these brown spots!! It's on both plants. Maybe 6-7 leaves had it.
Sprayed Neem Oil on them, not knowing if its bugs. But I definitely don't see any bugs. Cut off all the affected leaves.
Now 2 days later, after the Neem spraying, I see a few new spots appearing on other leaves.
Only thing new is, I've pruned my crops quite a bit.
Any ideas what these spots are?




 
axilotl, it appears to me that you're coming really close to loving your plants to death...

STOP worrying about every spot or blemish you see.
When I ran GH Flora, it always needed an ec above 2.0 for the girls to thrive in my DWC systems.
I think they are still hungry.
 
You must log in or register to reply here.
Back
Top