Having trouble with a new 2x2 DWC setup

Discussion in 'Hydroponic Growing' started by AzGrowerrrr, Feb 28, 2021.

  1. Hello all!

    This is my first grow in almost 20 years but it just became legal in my state(Arizona) so here we go.

    I have been having some trouble getting my plants going. I am adding lots of details to try to figure this out so bear with me. Before I get into that, here is my setup:

    -I am using Vision Seeds White Widow and Sweet Seeds Sweet Skunk F1. Both femisized.

    -I bought the Spider farmer 2x2(53” tall) tent setup with a fan and sf1000d light from Amazon.

    -I repurposed a humidity controller from cheesemaking and have it plugged into a humidifier. This keeps the humidity between 50-60%.

    -I put together a dwc rig with a big air pump and 3” net pots. I fill it with 7 gallons which puts it about 1/2” below the bottom of the net pots. I am growing 2 plants in this.

    - General Hydroponics Flora series nutrients
    -PH and TDS pens in addition to a ph drop kit

    To start, I soaked some rockwool in ph adjusted(6) water and then tucked a seed in each cube. I put these in a Tupperware covered in plastic wrap to make a humidity dome. I put these in the tent under the light. They sprouted and had a small root sticking out after 4 days.

    I filled up the reservoir with tap water and the first week of nutrients ph adjusted to 6 following this schedule:


    I had initially kept the tent inside the house as it was too cold to start in the I heated garage where it would eventually live. After a few days, the weather warmed up so I moved it to the garage. The light adds enough heat to keep the air temp in the 55-80F range even though it gets colder than that in the garage. I have not measured reservoir temp.

    I saw some yellowing on the seedlings so I started looking into problems. First off, I had a 3” hole I was using to add nutrients So the reservoir had a massive light leak. This may have led to the ph rising up to almost 7.5. The water is also very hard here so the ppm with these nutrients was 600. After a week I was seeing very little growth so I changed the reservoir and cut the tap water with 3 gallons of distilled water. I thought maybe I needed more nutrients so I upped it to the next level using the sheet above.

    This did not help. The next week I switched to a mixture of distilled and spring water. I went back to the week 1 level of nutrients and the ph has stayed right around 6 and the ppm is 390. The plants are still barely growing and look pretty yellow. The big one is about 2” tall and the smaller one is an inch. I am about 3.5 weeks from germination.

    I am going to switch to 100% distilled with cal mag and hydroguard today. I am thinking of going to 1/2 of the amounts listed for nutrients for week 1.

    Any ideas? Too much light? Reservoir water too cold? Should I add a top feeding bubbler to help them get going? I am grasping at straws and feeling frustrated. I have some more seeds and rapid rooters if it makes more sense to just start over. Any thoughts or ideas would be greatly appreciated! Thanks in advance!

    Here are some pics:

  2. Have any roots reached the water yet? I would feed until they do. I would also try to get your temps up also 55° is cold for a seedling
  3. Yes they have. They have been in the water for about 2 weeks. I am thinking root rot at this point
  4. There are a lot things that could be going wrong.

    Tap water might have to much gunk in it.
    My tap water dwc try failed because of that, so I now use a cheap RO filter system.
    A 50 gallon per day system can be had for around $50.
    The tap water was producing symptoms similar to yours.

    Your tent is likely to prove to be too short without extreme plant manipulation.
    My 9 ft tall tent is sometimes too short for autos.

    The 100 watts for 4 sq ft is on the verge of not being enough light.
    30 watts per sq ft is the usual recommendation, but 25 can work.

    I've experimented with pot size.
    My 4 inch pot trial had plants tipping over, so I went back to 6 inch pots.

    Water level distance below netpots is a non-issue.
    I've tried everything between 1 inch below and 1 inch above, and can't tell any difference.

    But the most damaging thing is probably too much food and/or light.
    You won't be too far off in hydro if you have ppm = 100*Week# as the seedlings gain size.

    Using the 500 ppm scale, I start seedlings at about 30 ppm, then increase a little each day.

    Bear in mind that in the time between sprouting and getting roots into the reservoir a lot can go wrong.

    Light leaks shouldn't be an issue at this age.

    2 hydro plants in a 2 ft x 2 ft tent will produce an uncontrollable jungle.
    I've reduced the number of autos from 2 to 1 in some 2 x 4 tents because of jungles.

    I'm using GH flora nutes in hydro right now, and if I used 1/4 tsp micro + 1/4 tsp gro + 1/4 tsp bloom + 1 tsp CalMag in 1 gallon of water, it would produce ppm = 530 on the 500 scale, which would fry my plants to a crisp if given within the first couple of weeks.

    Whenever I encounter problems, I raise lights, add CalMag, and reduce the other food.
    If successful, changes might be noticed in a few days, but not immediately.

    Too little food will produce too-light new growth, but too much food is poison.
    Any too-light growth is easily remedied by more food.
    Too little light will produce some stretch, but too much light is poison.

    Paradoxically too much food can produce elemental lockouts that result in yellowing from the underfeeding of the locked out elements. And many other issues.
  5. Thanks for your advice, I really appreciate it. The tent size and light are what I could afford/fit.

    I will definitely be doing some training and mainlining to make the most efficient use of the space.

    I will be treating the roots for root rot and switching to distilled water tonight. RO water is easy to get here so I will go that route moving forward.

    As far as nutrients, I was planning on 1/2 of what was recommended for the first week but maybe I will try 1/4 of that.
  6. Ok. So I think I’m on the right track.

    I took apart the whole reservoir and scrubbed everything with antibacterial dish soap. I then coated everything with Starsan which should make it sterile. I also soaked the hoses and air stone in starsan.

    I cut the rockwool away and the roots didn’t look too bad. I cleaned then and then poured a hydroguard solution over everything as per the aqua man article.

    I reassembled everything and filled up with distilled water. I added a low amount of the flora nutrients with cal mag and added the correct amount of hydroguard. I mixed everything thoroughly and got a ph of 5.75 and a ppm of 160. I will give it a few days and see how it looks. I will keep treating the roots every day for 4 days like aqua man said to do.

    Wish me luck!
    • Like Like x 1
  7. Well, after another week of zero growth and one of the seedlings’ flowers curling up, I think I might have to start over with new seeds. The only other variable I can think of is the water temp in the reservoir. I’m going to get an aquarium heater to keep the water the correct temp. Kinda bummed that things went so wrong.
  8. #8 ZeroSkill, Mar 7, 2021
    Last edited: Mar 7, 2021
    So questions.
    Is your Tote directly on the floor?
    what is the air temp in the tent during light / dark?
    Your exhaust system, does it run constantly, or only when limits are reached on a controller?
    Are you leaving that hole open all the time in the top of your tote?
    Why is the tote not at least painted so no light gets through?

    What current stage of growth are you in? As far as ppm's and stuff goes, here is a handy chart:
  9. Thanks for your comment, Ive got answers!

    The tote is sitting on the ground but there are 2 layers of tent between it and the ground. I do not have the exhaust fan running at all to preserve the heat inside the tent. It is ranging from 65-80F and stays right around 60%rh. I will measure the temp of the red water tomorrow morning as that is when it should be the coldest.

    The hole on the top that I use to take ph and ppm measurements is covered by a patch of duct tape whenever I am not taking samples of the water so it is sealed and opaque.

    The tote is black and the lid is yellow, both are completely opaque.

    Since my last res change a week ago, I am sitting at 6.15ph and 160ppm. I have been treating the roots with hydroguard as per aqua mans instructions and they no longer have any brown spots.

    Please let me know if you have any other questions.
  10. Hey man! I failed my first dwc attempt too. Went back to soil. Good luck :)
  11. That is not enough insulation if your water temp is that low. Water temp for DWC needs to be around 65-69 f. Water that cold is no good. I have my totes on a wooden platform. As space is limited, get cardboard, at least 2 or maybe 4 layers under the res. Whatever it takes to make the water not that cold.

    I also had to buy a water chiller, as the water, once properly insulated, will take to the average temp of the tent.
    You do not want your tent going over 75. 60% rh right now should be your tent max.


    I edited my first post but will put some info here as well. I am not sure what size your plants are. But 160ppm. not enough nutes. Unless its a small seedling. Just sprouting.
  12. I just put a few pieces of plywood under the tote and checked temp. 75f in the reservoir and 75f ambient temp.

    Temperature is challenging here. For example, it was 40 here this morning and is currently 85. Big swings in the desert. Thanks for your help. I will add more nutrients tonight
  13. Also, do
    What is the ambient temp outside the grow tent? Is that stable? Can i see a pic of your plants?

    the reason most people have trouble with dwc is water temp. the higher the temp, the less nutes/oxygen the roots will uptake. Really, 68 is the sweet spot, just like 5.8 is the sweet spot for ph.
    I purchased an aquarium water chller. Not cheap. At all. But it all depends how industrious you are. Your average temps of the area outside your tent, and how creative you can be for water temp. as close to 68 as you can without as much hassle. I'm a mechanic by trade. Find an old radiator. Shit, look for some overclocking radiators or something you can put fans on if your low on money. Long as it removes heat from the res. its good. I've seen people pump water from the res, into a hose in a bucket, inside a mini fridge. you know, 25 ft or whatever in the bucket, looped around and around. I'm sure you get the idea.

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