Do bubbles give o2 to the roots or just kill pathogens?

[lysol]

I've read that the bubbles add very little to DO ( dissovled o2 ) but it just functions to kill waterborn diseases.

Then I've read that the bubbles are the "engine" providing the o2 for root growth.

Ummm... cognitive dissonance. Which one is correct or are they both true? The former makes sense to me and I guess the roots get most of hte o2 from their air gap between the water and medium? I'm talking DWC obviously.

I want to know exactly how it works, if my plant is overwatered there is no point in spending 100s of $s on pumps when all I have to do is calibrate my air gap, and visa versa, I dont want to screw around experimenting with air gaps if all I need to do is go and out buy a pump....

I am not currently experiencing any issues but I just want to be proactive and understand how my system works.

TIA

 

[Aerohead]

Bubbles give O2 to the roots, get that water roaring with them, you won't regret it...

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........ 1,000,000 bubbles can't be wrong.........

 

[Aerohead]

If it wasn't for the bubbles in the sump, where would you get the O2 from in the air gap?

 

[FreezerBoy]

DO comes from surface turbulence. Waterfalls are the most effective means of aeration. A sheet of water with two turbulent surfaces crashing through a third surface. Bubbles disturb the surface and provide circulation to pull the oxygen down into the tub. They also force stale air out of the gap. I haven't tried it but, seems to me that once oxygen is removed from the tub, it would be the same as drowning a plant in soil. Air and water are no good if they're not fresh.

 

[lysol]

If it wasn't for the bubbles in the sump, where would you get the O2 from in the air gap?

Do you have to aerate an aeroponics rez for the roots to get o2? My thinking was maybe they got o2 from the roots, I guess there really is a lot of mis-info, I've read alot about bubbles only kill pathogens. Which had me confused.

Also before the roots hit the water they must get the o2 from somewhere as well.

I guess what I was overlooking is when some of the root zone is _under_ water is when bubbles become absolutely essential ( not that I dont have them running now to splash water up, just trying to think about this )

Thanks for the replies as always, love picking your guys brains

 

[LJB]

Note that this chart was copied from a koi pond enthusiast's website. Those people are the masters of DO.

 

[LJB]

Do you have to aerate an aeroponics rez for the roots to get o2? My thinking was maybe they got o2 from the roots, I guess there really is a lot of mis-info, I've read alot about bubbles only kill pathogens. Which had me confused.

Also before the roots hit the water they must get the o2 from somewhere as well.

I guess what I was overlooking is when some of the root zone is _under_ water is when bubbles become absolutely essential ( not that I dont have them running now to splash water up, just trying to think about this )

Thanks for the replies as always, love picking your guys brains

You need to aerate the reservoir. One of the points of DWC is to use water to get oxygen to the roots.

And for general info., quoting Norm Meck:

Whenever air is in contact with the water, whether through natural or artificial means, a transfer of oxygen from the air to the water takes place until the water becomes saturated.

[..]

Almost all of the oxygen dissolved into the water from an air bubble occurs when the bubble is being formed. Only a negligible amount occurs during the bubbles transit to the surface of the water. This is why an aeration process that makes many small bubbles is better than one that makes fewer larger ones. The breaking up of larger bubbles into smaller ones also repeats this formation and transfer process.

http://users.vcnet.com/rrenshaw/do.html

 

[*mistress*]

Do you have to aerate an aeroponics rez for the roots to get o2? My thinking was maybe they got o2 from the roots, I guess there really is a lot of mis-info, I've read alot about bubbles only kill pathogens. Which had me confused.

Also before the roots hit the water they must get the o2 from somewhere as well.

I guess what I was overlooking is when some of the root zone is _under_ water is when bubbles become absolutely essential ( not that I dont have them running now to splash water up, just trying to think about this )

Thanks for the replies as always, love picking your guys brains

can supply oxygen to roots by way of the room itself.

if have pots w/ access to room air circulation. holes in containers accomodate permeation of room air into containers.

bubbles are not essential for a deliver system. if using aero, can simply use sprayer and shallow pool for res. the space in between is air, or oxygen.

can even rig a tub/tote/ebb+flow tray to have in-out air from a ~50 cfm fan.

there is a point where saturation occurs, as in everything. cheapest air pump per bucket worked in past imaginary gardens, when ran aero buckets. no air stone/diffuer needed. they just get in way. place air tube in water and leave alone.

 

[FreezerBoy]

The reason you don't need bubbles in aero is the sprayers act as aerators. With DWC airstones serve two functions: as a silencer and to spread the bubbles over a wider area. An undiffused line, blorping in a corner, can leave roots on the far side of a tub too dry.

 

[Me2]

If the roots are immersed in an aeroponic res..its more or less dwc and needs aerating. If its simply a res for aeroponics then it wont need aerating, assuming its not too large and the res turnover rate through the system is reasonable, otherwise it will need some to keep it fresh.
I have around 7 gal of water that can`t be physically aerated, the system runs 1gph, so the only aeration it gets comes from 1gph of replacement water.

 

[lysol]

Gothya. I assume a root that never touches anything but air will still uptake o2, correct? Obivoulsy its better to have the root in an aerated rez tho so it gets nutes in addition to o2, but just saying, could an overwaterd plant in DWC also be corrected by widening the air gap? I ran out and bought more pumps today.

 

[FreezerBoy]

You can't over water a DWC. Water is the delivery system for oxygen. The more water the more oxygen. Some allow no airgap at all. While I've let it drop as low as 6 inches, I don't recommend it. While the upper roots are the airhogs they need to be damp. 6 inches is a long way for a bubble to travel

 

[needearly]

uh 50 gallon res 4x8 aerojet no bubbles needed what do ya think the jets are doing

 

[rrog]

Great thread. Another (possibly) interesting point is that if you're running CO2 in the air this will not reduce the O2 levels in the res. They are independent of each other.

 

[*mistress*]

If the roots are immersed in an aeroponic res..its more or less dwc and needs aerating. If its simply a res for aeroponics then it wont need aerating, assuming its not too large and the res turnover rate through the system is reasonable, otherwise it will need some to keep it fresh.
I have around 7 gal of water that can`t be physically aerated, the system runs 1gph, so the only aeration it gets comes from 1gph of replacement water.

does not need aerating if roots reside @ bottom of aero res. aero tub is air itself. no need to add to actual air roots are in. air is oxygen. that is the whole point of aero: to expose roots to air, and supply water, and/or nutrients as needed.
can simply drill hole in side of tub, if room's air circulation is very good; since oxygen is gas that permeates all gaps, will get into container.
cannot get better air diffuser than air itself.
keep water level just over single pump. all other space is air - that roots fill in.
keep humidity of container @ 100%. the roots will absorb water + nutes via water vapor pressure (rh).

Gothya. I assume a root that never touches anything but air will still uptake o2, correct? Obivoulsy its better to have the root in an aerated rez tho so it gets nutes in addition to o2, but just saying, could an overwaterd plant in DWC also be corrected by widening the air gap? I ran out and bought more pumps today.

yes, roots dont need physical contact w/ a rigid material to uptake oxygen. oxygen is a gas. plants are well adapted to gas exchange w/ the environment.

You can't over water a DWC. Water is the delivery system for oxygen. The more water the more oxygen. Some allow no airgap at all. While I've let it drop as low as 6 inches, I don't recommend it. While the upper roots are the airhogs they need to be damp. 6 inches is a long way for a bubble to travel

seems every gardener will find their own comfort zone @ which they set their res/water level - in any system.
have ran dwc w/ air stone/soaker hose/just hose. also aero bucket w/ no air stone and only pump w/ 1 sprayer, water level just over pump.
can have good or bad results w/ either, each method a little different.
keep ph in range, supply minimal oxygen, and all will be fine. can move on to other areas of garden.

Great thread. Another (possibly) interesting point is that if you're running CO2 in the air this will not reduce the O2 levels in the res. They are independent of each other.

water contains oxygen. h2o. this means hydrogen and oxygen are bonded. since water is constantly evaporating, oxygen is constantly being released - keep the root zone w/ access to water. the oxygen atom can attach to (oxidize) media, chemicals, bacteria, etc. also gets to roots (root zone), where is processed up thru plant during photosynthesis. plant's roots have to have enough pressure to draw up+push up water (containing oxygen). as long as external vapor pressure (water, again, in another state [recalling that water can take the form of a liquid, vapor, crystal, solid (ice)]) is less than the internal pressure, the plant will transpire the water, releasing water vapor and oxygen. same oxygen from root zone has been released into surround air.
entire room can be air stone, if enough holes in containers, and enough garden circulation.

hope this helps. enjoy your garden!

 

[NOYB]

My experience with hydro and DO is that large bubbles are what's important if you want to run an air pump. Small bubbles, if the same air flow, are not as good for raising DO as large bubbles. This is really the difference between running the same air pump with and without an airstone. Ditching the airstone also removes line resistance and the total airflow increases which helps.

Surface agitation is what's important here and impact like in a waterfall, or large bubbles disturbing the surface, has the greatest influence on DO levels IME.

If running in a closed room best to keep the air pump, if using one, outside of the flower room otherwise you will most likely find res pH dropping due to the increased CO2 level circulating through your res.

It's more important in hydro systems like DWC to have high res DO levels opposed to something like Ebb & Flow cause most of root aeration occurs with the flood and drain cycles. Res DO is still important but not as much IMO with something like E & F over DWC. The flood and drain cycles themselves 'crashing' back into the res, depending on how you have things set up, increases DO levels a lot.

I just got my first aero cloner and one of the first things I did was install a small open lined air pump into the res to run when the water pump is going.

 

[FreezerBoy]

does not need aerating if roots reside @ bottom of aero res. aero tudoes not need aerating if roots reside @ bottom of aero res. aero tub is air itself.

You still need aerated water. While the aero method aerates without an airstone, aeration is still required.

 

[Me2]

@mistress..won`t quote to save on bandwidth :wink:
If the root chamber hasn`t any standing water in the bottom then it won`t need any extra aeration. The res will still need some to keep it fresh, it could turn funky if not.

 

[*mistress*]

You still need aerated water. While the aero method aerates without an airstone, aeration is still required.

'aeration' is the actual air in the bucket, where in other systems, media would be.

1-cheapo water pump.
1-3" piece of 1/2" vinyl hose. end bend ove and zip tied to increase pressure.
1-18" piece of 1/8" vinyl tubing.
1-5 gallon bucket.
1-5" net pot.
1-cheap sprayer, attached to 1/8" tubing. 1/8" tubing inserted into hole-punched 1/2" hose.
*drilled 2 1/2" holes on either side of bucket, at top. this facilitated air exchange w/ room itself. room became air pump.

@mistress..won`t quote to save on bandwidth :wink:
If the root chamber hasn`t any standing water in the bottom then it won`t need any extra aeration. The res will still need some to keep it fresh, it could turn funky if not.

extra aeration is not necessary, even w/ standing water on bottom of pot/container/res. water just need to be moving. 1 pump can accomplish this.

adding hydrogen peroxide will help in any event.

member pirate runs aero w/ no air stone. may want to check out that member's garden.
if you see definable enhancements w/ an air stone, use one.

hope this helps. enjoy your garden!

 

[Me2]

By virtue of the fact the pump is moving the water in the res,its aerating..standing water isn`t usually moving and i didnt mention bubbles :wink:
Running an aero system that draws just 1gph from a 50 gal res you`d need to add some form of aeration to stop the res from going stagnant. A sprinkler/sprayer type aero running 24/7 would likely have sufficient water turnover not to need anything more.