Air stones needed for DTW coco resevoir??

Discussion in 'Advanced Marijuana Cultivation' started by TurboTokes, Sep 12, 2017.


    TurboTokes Well-Known Member

    Im slightly confused mainly because I can find little to no info on this topic. Currently I handwater in coco and smart pots, mix up 2 gallons of room temperature well water, add nutrients, and feed.

    I would like to automate feeding 2-4 times a day (system is already built with drip lines and "sprinklers" (they spray a 5" circle gently)

    My question is if the resevoir needs to have air stones to add dissolved oxygen to the nutrient water, or is the exchange of air in water that happens when you feed plenty for the roots? My pots are also fabric pots so I feel no shortage of oxygen is in the root zone, but I distantly remember being told there are various types of 02. I understand more DO is probably a good thing, but I like simplicity and maybe my 68* degree water already has plenty of DO and is all the plants need, making it moot to add another component to the system

    I am using generaly hydropoincs flora series, which is not thick and does not settle (atleast in the 15 gallons I mix and use in a week) so I am not interested in adding another pump to this resevoir simply to stir the nutes, as I dont feel that necessary with this nute line.

    Curious for some opinions!
    OldMedUser likes this.

    SwitchHitter Active Member

    use the smallest water pump you can get for mixing the solution. Can even put the pump on a timer as to not raise your water temp by running the electric motor 24/7. I too have a res, with drip feed DTW coco in 3gal fabric pots. my feeding pump kicks on, blasts some unused water pressure back into the res. No airstone...Unless I am mixing fresh nutrient. Then I toss a stone in the 55gal to stir things for an hour or so(overkill maybe)
    and we treat coco like hydro(it is) and water 5-8 times per day(once to a full 30% runoff. the other times it feeds just a small burst of fresh food)
    OldMedUser likes this.
    Chip Green

    Chip Green Well-Known Member

    This is of high interest to me as well. I'm just now taking on pure coco, in 3 gallon fabric pots. Currently hand feeding, with the GH Maxi duo, to get my "feet wet" in this area. It sometimes amazes me how, I reach a "plateau" in my learning, then suddenly a discussion pops up, with precisely the idea I'm contemplating....
    I am so grateful for the sharing of this valuable experience.
    OldMedUser likes this.

    OldMedUser Well-Known Member

    If your rez is just to keep your pots wet and not recirculating I'd add a small air pump to it. I charge my 5gal jugs of RO water for many hours before using it on my plants. Probably saturated with O2 in half an hour but for the 2¢ a day it cost to run a small air pump why not. :)

    ruwtz Well-Known Member

    No airstones in my coco drip dtw res and no problems. Only time I did have issues was when adding bennies to the res.

    Keep it clean, change often, and keep out the light.
    OldMedUser likes this.
    J Henry

    J Henry Active Member

    OK curious...
    How would you really know if you need more dissolved oxygen or not other than just guessing and guessing again? Of course you would not know by looking at the res water, smelling or tasting it.

    It takes a considerable amount of oxygen (not Nitrogen) to metabolize food to produce the sugars that fuel the cells - Google "Krebs Cycle" and see how aerobic (oxygen loving) plants, animals and microbes process food into energy to grow and thrive at the cellular level, it's a real big deal.

    Air is not oxygen, actually air is always 80% Nitrogen regardless of the volume pumped. All the air you pump and bubble through bubblers is always 4/5 Nitrogen gas. If you really think dissolved oxygen (O2) is a big deal, here’s an option for you.

    You do not have to guess and hope and wait and see if your roots are suffocating, dying and rotting every morning… test your res DO and find out for sure. See if you are winning or losing the DO game before your roots are sick, dying and you catch a dose of the root rot and then the fungi always come quickly to eat the decaying roots as soon as they smell death.

    Bet you will never see vultures sitting on post around a cattle pen containing health stock, have you? But you always see a whole colony of buzzards around close to dead cow in a pasture that died 2 weeks ago, that is stinking, rotting and decaying -- that smell of decay always attracts many buzzards and billions of fungi for the feast. Same deal, decaying cow, decaying DWC cannabis roots... a natural feast for buzzards and fungi respectively.

    Are your roots always getting enough O2 with your super air pump and 3 bubblers running 24/7, humming away or maybe not humming at all, you would never really know for sure until it is way to late and the crisis is discovered and in progress.

    Oxygen, dissolved — CHEMets® Visual Kit
    Catalog No.: K-7512
    Range: 1-12 ppm
    MDL: 1 ppm
    Method: Indigo Carmine
    30 tests

    More root mass and more Benny’s always consume and require and more dissolved oxygen to remain healthy and thriving. That total oxygen consumption must be subtracted from the DO Chart for a more accurate assessment of how much DO you need to keep the roots and Benny’s healthy and prevent low oxygen problems (suffocation).
    ruwtz likes this.

    MJCanada Well-Known Member

    I didn't read through the entire thread, but quoted this person because I believe it to be the right response :D

    When you are watering a medium, not using hydro, dissolved oxygen is essentially meaningless. There is research out there that shows water (regular H2O) cannot hold enough DO for a plant when used in a grow medium. The DO is used up before the plant can use the water, regardless of how much DO you put in prior to watering. The type of medium (coco coir, soil, compost mixtures, etc) doesn't matter.

    In hydro, you need to maintain the DO in the water, which is why you need to constantly be exchanging the water that is exposed to the air(bubbling, cyclone/vortex)... so it can replenish the oxygen that the plants remove through their roots.

    Now... bubbling to mix a nutrient solution into your reservoir prior to spraying your plants is a completely different topic. I would think a cyclone re-circulation system would do that better though??
    J Henry

    J Henry Active Member

    Specifically, what kind of issues did you have when you added Benny's to your res and how quickly was the onset of the problems? Just wondering what problems you had and how you corrected these problems.
    J Henry

    J Henry Active Member

    The scientific research I’ve read indicated that hydroponic grown lettuce thrives in 2 PPM DO. 70F water saturates at 9.2 PPM DO. So lettuce thrives at approximately at 18% DO saturation and change.
    Tomatoes also thrive in low DO environs/DO saturation res water.
    In your opinion what do you consider the optimal “safe” DO range required for DWC cannabis including the total Benny colonization?
    I realize that it is very common that many people consider the DO and DO Sat required for lettuce and cannabis to be the same as cannabis, 1 shoe fits all so to speak.

    MJCanada Well-Known Member

    I haven't looked into DO ranges for hydro grows much. I am a soil grower.

    There are ranges for different types of plants. Usually when referring to environmental conditions for optimal growth you can group based on classification of plant (e.g. perennials have similar optimal growth conditions from micro macro nutrient, to DO...).
    OldMedUser likes this.

    ruwtz Well-Known Member

    Running a living res is a fragile balance between beneficials and unwanted pathogens and there's not too many success stories of doing this well. Airstones do not guarantee success for the aerobic goodies. Adding bacteria/myco/tricoderma etc to the res means they require nutrition, which means providing a food source that competing organisms will also relish. It is a war on the micro level and it is easily lost, sometimes in a matter of hours. Along comes the nasty sludge and possible pH spikes, then your bennies are killed off by adding pH down rendering the whole thing pointless in the first place.

    Algae is phototrophic and will bloom quickly in an unprotected res. I've been there too.

    I see no reason to be adding bennies to reservoirs when they make excellent teas in their own right. Mycorhizzae in particular will not appreciate sitting in water. My only addition is Hydroguard (bacillus) promoting root zone health as it is very stable in the res.

    ps. I have a drip recirc system in veg and I clean the res every week to avoid any problems from those teas washing back into the res. I'm also trialling adding enzymes to the res to reduce this work, although I can't speak for its efficacy just yet.

    Lots of info around on using H2O2 and chlorine for clean res.
    Last edited: Sep 16, 2017
    OldMedUser likes this.
    J Henry

    J Henry Active Member

    Your right, dirt farming is different than hydroponic farming in in many aspects.
    I’ve read in the scientific literature that hydroponic grown lettuce thrives in res water containing 2 PPM DO concentration. If that res water was 70F and if the DO Chart doesn’t lie, 70 F fresh water that is 100% DO saturated and will contain 9.0 PPM DO.

    So… 22% DO saturation is great for lettuce, but lettuce is not marijuana.

    What do you think is the optimal DO saturation required for hydroponic marijuana? If you don’t know for sure, guess.

    rkymtnman Well-Known Member

    show us a pic of what temp and DO sat your reservoir runs at Ms Henry.

    whatever yours is must be good since you are not a hobby grower.

    OldMedUser Well-Known Member

    This whole thread is so much BS.

    Just bubble your nutes and DO will never be a problem.

    Who f'n cares if 2% is enough or 10% is too much.

    Trump is heading us into WW III so none of it matters a bit. :D
    MJCanada likes this.

    boilingoil Well-Known Member

    No stones in my rez in coir DTW. My reservoirs get used up in a week's time and are air tight till I open the vent for feedings.

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