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DWC - Help needed please!

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  • axilotl
    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).

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  • UndergroundFarmer
    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.

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  • BakedMoose
    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.

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  • Tersky
    commented on 's reply
    Ugh i wish i had a good answer for that but found this thread

  • axilotl
    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?


    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 by axilotl; 08-20-2020, 02:32 PM.

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  • crucialbunny
    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.

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  • DW2
    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.

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  • Tersky
    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

    Leave a comment:

  • axilotl
    started a topic DWC - Help needed please!

    DWC - Help needed please!

    Hi all,

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

    DWC in 2 single buckets.


    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.

    • 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:

    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.


    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?


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