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Is changing res water in dwc really necessary?

Discussion in 'Hydroponics / Aeroponics' started by BadlyDrawnBoy, Jul 24, 2017.

  1.  
    BadlyDrawnBoy

    BadlyDrawnBoy Member

    Theoretically, if you're keeping the water clean and roots healthy, couldn't you just keep adding fresh water to the res? ...along with nutes and (hydroguard) ... maintaining desired ph and ppm.

    For how much the plants drink later in their lifespan, it seems to me the water would be completely, newly cycled every week or multiple times a week anyway, just by adding so much fresh water to top off the res.

    This is my first grow, and I'm just theorizing and planning for the best and easiest path. The plants seem so happy in the water they're in, and the water has no smell and the roots look fantastic. Seems I could just keep topping off and adding nutes to maintain the ppm range I'm going for.

    Has anyone had success doing it this way?
     
  2.  
    FennarioMike

    FennarioMike Well-Known Member

    Eventually you should. I have run a full 4 week veg cycle without changing the nutes. I actually compared 4 buckets with Hydroguard and 4 with UC Roots and let the rez temps stay in the high 80's - low 70's and didn't change the rez once. I topped them with RO or fresh nutes depending on their uptake. They all grew great. I'll always do it this way from now on.

    But that's about the duration that I myself would go before a full changeout. The plants aren't going to take up all the nutes together at the same time. It might take up one faster than another, or one not so much at all. Eventually your rez can become completely chemically unbalanced and nutes getting locked out even though your pH and PPM look ok. Eventually you want to flush out that spent shit and start over.
     
  3.  
    BadlyDrawnBoy

    BadlyDrawnBoy Member

    That makes sense. My plants are only a bit over 3 weeks, so they aren't taking in much nutrition yet. I've changed the res once and twice on the other, but probably could have just gone the whole first month without a full res change. The ppms are only slowly dropping, so I haven't felt like i needed to add more nutes yet. But I understand about the plant using some nutrition more than others and eventually the res will have too much of something and a lot less of another. Makes sense.

    I see posts where people say their dwc is empty when they check on it because the plants drank so much. That is mainly what got me questioning the necessity for full res change, since if the plant takes all the water in a few days, there wouldn't be any water left to change out anyway, and what you add to it would be a fresh res change. But in early veg stages, that's not happening yet obviously.
     
  4.  
    FennarioMike

    FennarioMike Well-Known Member

    Yeah I can't speak to that that so much. I veg in 5 gallon buckets but move them to a big RDWC system for flowering. In peak mine probably drink about 6 or 7 gallons a week each. So much easier changing 1 rez than multiple buckets...
     
  5.  
    BadlyDrawnBoy

    BadlyDrawnBoy Member

    I'm just looking to get a modest yield, probably won't be doing anything more than single pot hydro or soil. I'd like to try soil next, just to compare. Seems it may be a bit cheaper overall doing soil. Loving the way the hydro is working though, seeing the white roots expanding into open water and the plant growing happy above. But I'm the type who prefers a set it and leave it type approach, so soil is probably forthcoming. Nice for a first grow to be more involved with the plant and tending to it, I do enjoy it.
     
  6.  
    Airwalker16

    Airwalker16 Well-Known Member

    Only time I do it is going from veg to flower. you're correct in saying they drink so freaking much that you need to replace so often there's almost No reason to switch.
     
  7.  
    BadlyDrawnBoy

    BadlyDrawnBoy Member

    How long do you veg for? I was planning on beginning flower when they're a bit less than a foot. I'd like to keep them on the smaller size. One is 6 inches already now
     
    Airwalker16 likes this.
  8.  
    PetFlora

    PetFlora Well-Known Member

    Depends on ho many plants your rez is feeding and how big they are
     
    Airwalker16 likes this.
  9.  
    BlueBlazer00

    BlueBlazer00 Member

    Depending on how big your grow space is , i veg d mine for about 6 weeks before i switched to flower to fill a 4x4 grow space . :clap:
     
  10.  
    BionicΩChronic

    BionicΩChronic Well-Known Member

    I do a rez change bout every 4 weeks. And when switching to flower. I run 3 in a 18gal tote with copious amounts of great white
     
  11.  
    JSB99

    JSB99 Well-Known Member

    Lots of variables
    • How much water in your system? Larger volumes of water will last longer
    • Water temps - higher temps can create root root and slime
    • Exposure to light - light will encourage microbes to grow, creating algae and slime
    I'm going to have around 80-gallons in my 4 plant RDWC. I'm going to see how the water's doing when I flip them. I'd like to go the whole grow without flushing, but I might flush when I flip.

    More water has a lot of benefits
    • Stays fresh longer
    • More pH/nutrient buffer
    • Helps keep water temps down
     
  12.  
    Twerkle

    Twerkle Well-Known Member

    Not changing your water weekly or every 5 days in DWC is like buying a Ferrari and never going over 5mph!
     
    JSB99 likes this.
  13.  
    JSB99

    JSB99 Well-Known Member

    I'm actually going to flush every other week. I've got a lot of water (50 - 60 gallons) and only 4 plants. I'll play it by ear.
     
  14.  
    Twerkle

    Twerkle Well-Known Member

    Trust me i know the pain of changing i got 120gallon rez of RO so i use between 300 to 400 gallons of prefiltered water a week. but water is cheap and why decrease your yield to penny pinch.

    the reason we grow dwc is because we get to submerge the plant in the perfect mixture of nutes at all times. if you are not changing regularly or if you are only topping of with new nutes and water you have no idea of the contents of the rez anymore. at that point might as well do soil.
     
    JSB99 likes this.

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