Can you run a recirculating reservoir for 2 weeks...?

Discussion in 'Hydroponics / Aeroponics' started by Akira90, Jan 6, 2018.


    Akira90 Member

    i often see 7-10 days and change the reservoir on instructions. If I have a chiller, excessive airation to the point where it’s stirring the ferts and ppm / pH is kept in check with RO water, etc, can a res last 2 weeks with healthy plants?

    If no, can someone explain if the deets oxidize, plants excrete something etc? Trying to learn and understand more and reduce the time so I can spend more time super cropping / training the plants.

    Thanks in advance for your time. :)
    redi jedi

    redi jedi Well-Known Member

    Depends on the volume of water/nutes, how many plants and where they're at in regards to veg or flower. My veg system..50gals with 8 plant sites.. can go 3 weeks without needing any attention. My flower system...90 gals with 8 sites also...will need daily attention by week 5-6.
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    klx Well-Known Member

    The reason people say to dump your res regularly is because your TDS meter only measures the total salts in your res and it is impossible to know what ratio of N, P or K the plant is using. Therefore if you top up your res the NPK ratio will not be as per bottle.

    Having said that, I often go 4 weeks without dumping a res and just topping up with water and nutes. I have not noticed any difference to the plants. Just use a good 2 part synthetic nutrient and keep your res pathogen free with H2O2. Easy as winking.

    Airwalker16 Well-Known Member

    I don’t change mine for the entire run. I just keep topping off until I need to flush. That’s the only time I’ll empty and fill with just pure RO water.
    30 gal system, 8 5 gal sites with a 7 gal Rez, chilled at 66-68* always.
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    Cold$moke Well-Known Member

    Im on almost 4 weeks with no dump in one setup with raw nutrients.

    Depends cause my other system isnt as stable with advanced nutes
    But i have 4 plants from seed in it so i dont know if their nutritional need are the same but 1 plant out of 4 shows heavy mag deficiency
    2 look great and one is in between ..

    My 5 gal bubblrr has been also going with a clone for 3 weeks no change either.

    Just depends on too many variables.

    And i also have made runs with no dump just top off
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    Akira90 Member

    ... sounds like it’s better safe then sorry. How quickly do you think plants show symptoms of deficiency after the res actually goes south?

    zypheruk Well-Known Member

    usually over night in dwc.
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    Lordhooha Well-Known Member

    I wait at least three weeks unless I have something going on with the water or plants which is rare anymore.
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  9. Just as an example, my last grow I only had 2 res changes total. Issue was that during mid flower, she wasn't eating up nitrogen nearly as much and my ppm level was filled with nitrogen (but still a high number like 900ppm). I did not know this was mostly nitrogen, leading to some clawing and less P and K available to the plant. She was still dark green after a light flush and harvest.

    For my current grow I've been at 270ppm for weeks 1-3 then changed res up to 570ppm for week 4-5 and now I'll change it again and start adding more FloraBloom
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    JSB99 Well-Known Member

    With 55-gallons in my rdwc, I do a flush every three to four weeks.
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    Cold$moke Well-Known Member

    Nice im only running 24-30 gals going about 4 weeks strong i havent even checked ph:eyesmoke:
    I figured if they are still looking happy as hell why change it lol
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    JSB99 Well-Known Member

    I hear ya. Everytime I flush, it's a battle trying to balance the new water! I like going a couple days with no nutes after flushing, but my pH swings wildly, until I add nutes, then it balances right out!
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    Airwalker16 Well-Known Member

    flushing water doesn't need to be pH'd. pH levels are for nutrient uptake, not water.
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    JSB99 Well-Known Member

    Thanks man! I was wondering about that a while ago, but then forgot to look it up.

    That'll make things easier! Little details :)
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    Cold$moke Well-Known Member

    I dont think he meant he was trying to ph the water he just meant its not stable till he adds nutes . I think lol

    I always thought if your flush water was ph'ed it would allow for the plant to better metabolize
    The remaining nutrients in the root system and stored in the plant .

    Because of the different nutrient absorption ah different ph levels hence why plants eat best in the 5.8 to 6.3 range
    I figure if the plant gets a lockout at ph7.5 to 8 (my water)
    would it still burn up the remaining nutrients in the root system and stored in the plant?

    When i "flush" i like to run ph water for one week and regular or even better RO water so it really strips the salts out.

    These are only my own methods as i dont have any proof to back it just what i imagine :)
    Last edited: Jan 11, 2018
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    JSB99 Well-Known Member

    He was right. I was trying to balance my fresh water :)

    I kind of do what you do, to strip the salt build-up.
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    Akira90 Member

    Ill try to run mine for a few weeks and see how that goes. Thanks everyone.
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    CharlieBravo Member

    Is it safe to assume that the smaller the amount of water (ex 5gal) the more frequent you need to change reservoir water than for a larger size (ex 15 gal?) Or are other factors more important to determine when to change out the water?

    Cold$moke Well-Known Member

    Your assumiton is and isnt correct

    With a 5 gal you wont have to change out often till the rootball gets big.

    Remember with a 5 gallon bucket your only able to put about 4 gal in.... then when the root ball
    Filles the bucket you can only put 2.5 gal in
    And youll have to top it up almost every day.

    For your 2x2x3 box it would be best to find a container that is big enough fit in side
    And still give you adequate height
    This will be a tough one though

    And i suggest using a light that can be close to the tops of the plants like t5s. I cant imagine putting anything bigger in there

    Hope this helps
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    CharlieBravo Member

    Coldsmoke, yes it does. I'd "like" your response but I don't have that button yet.

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