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DWC - Help needed please!

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    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?


    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


    • axilotl
      axilotl commented
      Editing a comment
      But isn't that the reason for using FloraMicro softwater as opposed to FloraMicro hardwater? In theory I need to still supplement CalMag ?

    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.
    Smoke weed,.....grow peace!


      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?


        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.


        • Tersky
          Tersky commented
          Editing a comment
          Ugh i wish i had a good answer for that but found this thread

        • DW2
          DW2 commented
          Editing a comment
          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).

        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.
          Coconut Grove
          4x4 tent, Platinum LED P4-XML2, four Patio Pickers. Vegging Liberty Haze, Acapulco Gold, Lavender and Sweet Amnesia Haze.

          3x3 tent, Platinum P300 LED. Flowering two Tangies.

          Flower tent:
          4x4 tent, Platinum LED P4-XML2, four Patio Pickers. Vegging Super Lemon Haze, Durban Poison and two Tangie x Blueberry crosses.

          32"x32" tent with Feit white LED. Vegging four Mother's Finest.

          Coco/Perlite/worm castings/mycorrhizae living soil mix.
          Down-To-Earth dry amendments. Gnarly Barley added weekly. Eisenia fetida.

          On deck: Winter indicas.


            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).


            • DW2
              DW2 commented
              Editing a comment
              My local water supply runs about the same ppm at a pH of 7,25 and no problems with it.

            • UndergroundFarmer
              UndergroundFarmer commented
              Editing a comment
              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.

            • Rj420
              Rj420 commented
              Editing a comment
              I use orca microbes as an alternative to hydroguard

            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?!


            • UndergroundFarmer
              UndergroundFarmer commented
              Editing a comment
              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.

            • UndergroundFarmer
              UndergroundFarmer commented
              Editing a comment
              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.

            • Rj420
              Rj420 commented
              Editing a comment
              I do not put ph down and ph up into the same reservoir. If I put ph down in a reservoir and the ph starts falling I change the reservoir.

            Thanks for the info. I'll be mixing my next batch with approx 700ppm.
            Last edited by axilotl; 08-24-2020, 09:50 PM.


              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?


                It looks a little like either a little water got on leaves and HID was magnified by droplets and burned them or maybe leaf septoria Not 100% confident in the diagnosis so I'd see what others have to say as well.


                  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.
                  5x5 grow space
                  900w of Vero's and F-strips
                  4-17gal totes self-made UC system.


                    Tersky : I think the spots from septoria from the link you provided look lighter. My spots are more brown looking. Its an LED light but I guess the effect your speaking about could be the same. I really think I didn't get water anywhere on the leaves though.

                    gbauto : hahaha, I think you're right. It's the first grow and I somehow don't wanna ruin it. I want to succeed Didn't think an EC that high would be required for DWC: Everywhere I searched they said, as for EC values in DWC; they should be lower than the recommendations on the packaging. When I compare it with the Tripart Chart for flowering. The table in my first post is around 25% lower. Any thoughts?


                    • UndergroundFarmer
                      UndergroundFarmer commented
                      Editing a comment
                      I think those recommendations are for guys growing 40 or so plants in a flood and drain system.

                    • axilotl
                      axilotl commented
                      Editing a comment
                      UndergroundFarmer : Which means I should target in the lower range for DWC?

                    A question regarding general feeding:
                    I change my reservoir weekly and only top up with RO water daily. This is my PPM for the last week. Measurements were always made after topping up to the same water level.

                    Day 1: Freshly made solution 830 ppm
                    Day 2 730 ppm
                    Day 3 620 ppm
                    Day 4 550 ppm
                    Day 5 450 ppm
                    Day 6 (Today) 370 ppm
                    First grow, but it looks like they are feeding well.


                    1) Should I be topping off with nutrient solution ? If so, how strong?


                    • UndergroundFarmer
                      UndergroundFarmer commented
                      Editing a comment
                      I wouldn't just because it's a bit much work adding more nutes then more pH Up/Down just to maintain a certain ppm. As long as they are growing and still taking up nutrients during the week, they will be fine. I only add water and pH adjustments when needed during the week. It's OK and probably beneficial to keep them just a bit hungry. (I learned that raising tropical fish!) You're doing fine and they can get by on 370 ppm until tomorrow.

                    • Rj420
                      Rj420 commented
                      Editing a comment
                      I use 1/4 the amount of nutrients in my top off water as I do in a full res change

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