How do you recognize a low-oxygenation crisis with DWC pot grows


Most growers I know say when the root ball turns brown, gets slimy and smells rotten you probably have had a “low-oxygen” crisis with your DWC grow. Well, that is a no brainer… what you see and smell is what it is… it’s death and decay for sure and that will stink-up your whole house too.

Question: Does anyone here have a better way to ID this common low-O2 crisis before the slime and stink happens or do most of you just wait, watch and hope there will be enough O2 to prevent suffocation death and root rot fungal colonization to eat the dead mess in the tub?

The damage caused by oxygen deprivation/suffocation is seen in the roots before it seen in the stem and leaves.


You might need a better airstone that circulates more oxygen for the roots :slight_smile:


Thanks, would “a better air stone” or even more air stones and a bigger electric air pump squeeze more than 20% oxygen out of the air and give me more O2?

My question was: Does anyone here have a better way to ID this common low-O2 crisis before the slime and stink happens or do most of you just wait, watch and hope there will be enough O2 to prevent suffocation death and root rot fungal colonization to eat the dead mess in the tub?


Most of the time you wont know its there until you notice the smell or browinijg of roots, and I know my apologies for not answering the whole thing right away trying to get ready for work.

Yes adding another airstone and better quality electric air pump. To squeeze out a little more oxygen for the roots should help @JH231, also if I dont get the whole question answered ASAP give me a few extra moments to get you fully answered and helped :slight_smile: and yes it would give you more oxygen


Also res buckets should be black with no light penetration to prevent algae as,well as res temps at 67-70 degrees


You can tell before the slime and browning of the roots, you just need to be someone who checks their reservoir frequently. As the root mass grows, the air stone can get “strangled” by the roots, and aeration becomes a problem. Because remember, the bubbles don’t actually aerate the water, it’s only once they pop at the surface when they are actually aerating. So if you can see that the bubbles have diminished then you should start to take action to prevent and slime or root rot.

I recommend starting off with good air stones, and air pumps that can handle the needed output of air for each bucket. I ended up buying 2 industrial sized air pumps, and I absolutely love them! Also, having something like Hydroguard is crucial for keeping your reservoir clean and healthy.



Are you saying that If I get a bigger air pump, double the pump air volume and get better air stones, I can double the oxygen going into the water from 20% O2 to 40% O2?

And this will double the DO in the water from 100% Saturation to 200% Super Saturation too?


Is this all there is to it predicting and circumventing a low-oxygen crisis, preventing root death, root rot, and fungal outbreaks? Do your industrial air pumps make a lot of noise?


It doesn’t increase oxygen what it does is ensure it is there resist stones getting plugged up and make us feel better temp control and frequent changes with good flush practices keeps res free of Bacteria. That or adding bene’s if you are using organics darker roots and some slime is to be expected light leaks are another big culprit but minor discoloration and sludge can literally just be due to a product line.
A sterile grow can be done using no organic nutrients and regular daily administration of h2o2 as well as light tite res and frequent system cleaning
I tend to use enzymes to keep my res clean and reduce prevent slime they digest dead root matter and organics which may be in res.


Larger pumps tend to make more noise yes but not much more than an exhaust fan or Ballast fan and can be secured to cinder block or hung with bungies to reduce vibration noise


My industrial air pump, 16 outlet sites, isn’t much louder than the vent fan I use for my HID light. I also play music for the girls, so you really don’t notice it with the radio on. If it’s dead silent, then yea, you’ll notice the humming. @Donaldj is right on point with everything too, organic nutes can/will turn roots brown, but that’s normal. Otherwise, brown is a bad sign!



I am disappointed to hear that, “it doesn’t increase the oxygen…”
When the oxygen level is low in the water, low enough to suffocate the roots, it seems logical to me that increasing the dissolved oxygen in the water ASAP is vitally necessary for plant survival and if the bennies are aerobic organisms it is also vital for them too, else everything suffocates, dies and rots presenting ideal conditions for fungal colonization… Is this right or not?
Personally, I would feel much better knowing vs. guessing or hoping the DO is maintained continuously within the “safe range.” More pro active than reactive… good ideas to reduce electric motor noise and vibration, thanks.


I found this about DO and it’s dependence on water temperature, it seems you have to put the roots in a bad temperature range to get a higher oxygen level.


h2o2 increases oxygen and when I say it doesn’t increase oxygen what I mean to say is that water will only hold so much oxygen and the importance of a bigger pump is in essence to resist roots clogging. These are tried tested and proven methods of growing root rot is far less common in hydro than it is in soil it is taken more seriously in hydro since it is clearly visible and many have several plants in one system so spread is possible.
Many people get root rot in soil and chase other issues instead only finding it was root rot in the end also root rot in soil is typically halted by dry periods and microbes in soil which feed off decay.
If you are so greatly concerned you should look into fogponics may save you some stress but honestly I have little worry about root rot I keep my temps cool monitor and change nutes regular any signs of issues forming I flush res and change nutes


OK, I’m getting the picture.
I hear you saying that hydrogen peroxide is used to increase dissolved oxygen in the water when the plants are suffocating because of low oxygen. The water only holds a limited amount of dissolved oxygen, that is predictable with the DO Charts and air. When the water is too warm there is not enough oxygen for the plants and benny colonies and they suffocate. Then the fungal colonies thrive and the battle trying to kill the fungi is on.
Chilled water increases dissolved oxygen a little. That is the basic concept and sales pitch the water chiller salesmen use… chilled water is necessary if you want to increase the DO so buy a water chiller.
Or, If you have a low oxygen problem, use H2O2 to increase the dissolved oxygen in the water.
And, if you must kill microorganisms in the water, Clorox is cheap and will do the deed as will ozone gas.

Cutting to the chase now, in your opinion, what is the optimal safe DO Saturation necessary to keep plants and bennies alive, healthy and thriving for several months?


I believe we’ve had this conversation before you me @MacGyverStoner I don’t track DO since I change water as recommended and control temps without a chiller. If you intend to try and run res with same water entire grow you are looking more at aquaponics @Dumme would have best info for you on those systems of growing.
I am as many are here hobby growers and work on KISS policy I don’t need to know DO levels since what I do works just fine for me maybe others will have better information for you?


Thanks for the site.