DWC - diagnosing low oxygen crisis – How da-do-dat?

JohnM · Feb 25, 2017

Most growers make the low O2 DX after the root are sick, die, decay and the fungus presents. Then they go into the “crisis mode.” I have easy access to a DO meter anytime so that meter test results should provide a heads-up of any low oxygen problem at the onset, before the roots die and the fungi outbreak comes.
What DO concentration and DO Saturation indicated “low oxygen?”
I understand that most hobbyist do not have DO meters nor do they want a meter and actually have no logical way to test DO… most hobbyist totally rely on the DO Chart values and water temp and just wait watch and hope they won’t have low oxygen problems.

gaiusmarius · Feb 25, 2017

i think most dwc growers will go over kill with air pumps and water chillers to keep that water super oxygenated. i don't do dwc, so am only theorizing.

idrobud · Feb 25, 2017

Hi Guys!!!

English is not my language so I try to explain.

Mesuring DO concentration is Easy. Know when the DO level is good is not Easy.
Many variables for That:
1 Temps
2 Shape of the container
3 Co2 in the water
4 Distance between the diffuser and the water surface.
5 Size of the bubble spread
6 water movement

I'm an hydroponics system producer in my country and if for many thing less is more I think blow a lot of air in the solution is a good idea.

Low oxygen in the solution - slow grow
If you blow a lot of air in your DWC or RDWC system you can get almost a aeroponic effect with a low water level!!!

sorry for my english!!

Douglas.Curtis · Feb 25, 2017

15 year DWC here...
Airstones are more efficient than open lines. (multiple university and other studies verify this)
When the amount of water raises the pH of the solution, you have too much air. CO2 from the air is creating carbolic acid(edit: I've been told it's the opposite, the air is blowing the CO2 out of the water, which raises the pH). Back off a little and you'll have plenty of DO for veg and flower.

Simple and effective.

JohnM · Feb 27, 2017

Douglas.Curtis said:
15 year DWC here...
Airstones are more efficient than open lines. (multiple university and other studies verify this)
When the amount of water raises the pH of the solution, you have too much air. CO2 from the air is creating carbolic acid. Back off a little and you'll have plenty of DO for veg and flower.

Simple and effective.

Just wondering Doug... what does plenty of DO mean to you? Can you be more scientific like in your mind, what is the "safe DO Saturation range" for any DWC pot grow; 10% DO Sat, 45% DO Sat, 75% DO Sat, 100% DO Sat.

If the DO is not tested and confirmed, how in the world would you know if your winning or losing in the DO game?
I do realize the vast majority of the hobby growers guess, hope and pray there's enough DO, but it seems that no one actually knows what "enough DO" means. I have seen on forums that the general mindset among hobbyist DWC pot growers is that air is the same as oxygen and if you blow plenty air bubbles in the water then you will have plenty DO?
Do you think this general assumption is right or wrong?

Douglas.Curtis · Feb 27, 2017

JohnM said:
Just wondering Doug... what does plenty of DO mean to you? Can you be more scientific like in your mind, what is the "safe DO Saturation range" for any DWC pot grow; 10% DO Sat, 45% DO Sat, 75% DO Sat, 100% DO Sat.

Plenty of DO means the plant will have sufficient DO for rapid growth, without causing pH changes in the solution. DWC is set up during veg, the needs of cannabis for DO increases through flower. What works in veg can fail miserably mid-flower.

The other set up method is to use 3-4watts of pump power per 10 gallons of nutrient solution.

These methods have been proven with cannabis for decades, long before I ever started growing. They've served me well for 15 years now. :tiphat:

chris harris · Feb 27, 2017

Recommended amount of air for DWC, has been 1 ltr/min per gal. Too much air can cause friction resulting in raising your water temp. Never heard of too much air. The most productive hydro, aeroponics, and the use of foggers, attribute there success to the massive amounts of oxygen avail to the roots.

Douglas.Curtis · Feb 27, 2017

chris harris said:
Recommended amount of air for DWC, has been 1 ltr/min per gal. Too much air can cause friction resulting in raising your water temp.

The real reason is the temp of the air being pumped through raises the temp. Friction in the pumps maybe... not the water.

chris harris said:
Never heard of too much air.

Only when it contains CO2, like room air or in a sealed room. Once too much CO2 is being pumped through your pH will begin to rise, through the formation of carbolic acid. (edit: Again, this is wrong. It's the removal of the CO2 and carbolic acid which raises the pH)

chris harris said:
The most productive hydro, aeroponics, and the use of foggers, attribute their success to the massive amounts of oxygen avail to the roots.

These are "Roots-Out" systems, where they're not 100% submerged in nutrient solution. Apples to Oranges.

cravin morehead · Feb 27, 2017

in BigTokes sticky about basic water chemistry it is stated : Measure oxygen and make sure it stays in the aerobic range, which is typically above 6 mg/l oxygen.
hope that helps you out

cm

chris harris · Feb 27, 2017

Here's a link so no one thinks it's drivel"
http://www.simplyhydro.com/too_much_oxygen.htm
Written by Erik Biksa, well respected.
I got more, just don't have time to play right now.

Aeroponics, DWC,F&D, are only different methods used, but all share the same goal, to deliver nutrients, and oxygen to the plants.
Are you saying that plants roots, have different requirements for oxygen depending on the media they are growing in?
Too bad you don't provide links.

chris harris · Feb 27, 2017

Here's another one.

https://hydroponics.com/question/how-much-air-is-required-to-aerate-my-nutrient-solution/

delta9nxs · Feb 27, 2017

hey doug, co2 from the air creates carbonic acid in water not carbolic acid. i know it is a minor point but i thought i would toss it in here for accuracy.

it is also a weak acid and as such will tend to pull ph down.

Douglas.Curtis · Feb 27, 2017

delta9nxs said:
hey doug, co2 from the air creates carbonic acid in water not carbolic acid. i know it is a minor point but i thought i would toss it in here for accuracy.

it is also a weak acid and as such will tend to pull ph down.

Well then I've been wrong a lot. I've been letting folks know about it for years. As for it bringing pH down, must not be the cause then.

All I know is the pH goes up, when you add too much room air, and carbonic acid has been blamed for it. Don't care if it's daffy duck's toe jam, pH still goes up.

Douglas.Curtis · Mar 1, 2017

Whoops, missed this earlier...

chris harris said:
Aeroponics, DWC,F&D, are only different methods used, but all share the same goal, to deliver nutrients, and oxygen to the plants.

Yes, and they have fundamental differences in how their root systems are exposed to oxygen. Roots-in systems MUST get their DO from the nutrient solution itself. F&D and any other roots-out hydro system, with intermittent exposure to nutrient solution, have a dry out period where they easily absorb oxygen from the surrounding air.

This is hydro basics. No link required.

chris harris said:
Are you saying that plants roots, have different requirements for oxygen depending on the media they are growing in?
Too bad you don't provide links.

No, I'm saying different systems provide different amounts of oxygen to the root zone, depending on how they're set up and run. Exactly the same as above.

Again, no link required as it's hydro basics. :tiphat:

Douglas.Curtis · Mar 1, 2017

The fundamental problem, with learning hydro cannabis on the net, is the lack of distinction between roots-in and roots-out hydroponic systems. Everyone calls them 'hydro' without realizing the differences in pH (reservoir management), dissolved oxygen levels and root zone temperatures required/allowable.

JohnM · Mar 3, 2017

chris harris said:
Here's a link so no one thinks it's drivel"
http://www.simplyhydro.com/too_much_oxygen.htm
Written by Erik Biksa, well respected.
I got more, just don't have time to play right now.

Aeroponics, DWC,F&D, are only different methods used, but all share the same goal, to deliver nutrients, and oxygen to the plants.
Are you saying that plants roots, have different requirements for oxygen depending on the media they are growing in?
Too bad you don't provide links.

Do you think that if DWC roots are suffocating, dying or sick from lack of oxygen (low Oxygen)… that you can buy an air pump that delivers 2X the volume of air or water you will get 2 X as much DO and fix the low O2 problem?

Or even get a bigger air pump that will deliver 3 X as much air through bubblers and get 3 X more O2 per cubic ft. of gas delivered?

Is the relationship of air to O2 linear?

Any thoughts or ideas about more air or bigger water pump will delivers more O2 and fix the low O2 problem?
I would like to see more of what you have if you don't mind posting it.

JohnM · Mar 12, 2017

chris harris said:
Here's a link so no one thinks it's drivel"
http://www.simplyhydro.com/too_much_oxygen.htm
Written by Erik Biksa, well respected.

"...as far as the root system goes the more oxygen in the water the better. The smaller or finer the air bubble the better,..."

The writer does not define what "more oxygen" means?

This writer is saying that more air bubbles in the water insure more dissolved oxygen in the water? That's what it looks like he's claiming to me.

Did the math: If air contains 21% O2 and you double the volume of air bubbling into the water does this mean your doubling the oxygen, pumping 42% O2 into the water?

Patient comes in ER, presents with chest pain, blue skin, cyanosis, short of breath. ER doctor orders oxygen immediately, nurse brings in large, a very large electric fan and turns it on high, blows air in patients face. Tells patient you will be fine now, you are getting plenty oxygen now just as your doctor has ordered. Patient defecates in his pants and dies laying on the gurney with the electric fan (aerator) on high.

Drivel?

Douglas.Curtis · Dec 26, 2017

Yes, useless drivel.

You're flogging a dead horse. Use 1ltr/minute of air, per gallon of water and be done with it. It's worked for 20+ years... it'll work for you too. :tiphat:

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DWC - diagnosing low oxygen crisis – How da-do-dat?

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