Confused about the roll of oxygen.

Role that is. I have been doing exhaustive research into Hydro / DWC / Bio-Buckets / Ebb n Flo / Aquaponics / Aeroponics / Aquaculture but I can't pin down the oxygen needs of a plant. Some methods like DWC have the roots submerged in oxygenated water while aeroponics emphasizes the reverse method.

Obviously they all require oxygen in the water but some methods just rely on dissolved oxygen in the water either by air pump or waterfall while others seem to emphasize "excessive" aeration of water.

I have read that obtaining 100% oxygen saturation in water is VERY easy with either an airstone or waterfall especially in the relatively small reservoirs that DWC / hydro setups utilizes. I have seen a bio-bucket setup that has a 500 gallon resovoir that only uses the 2 12" waterfalls of returning water to the reservoir to oxygenate the water.

That being said:

I have seen plants grow wonderfully using ONLY dissolved oxygen in the water via waterfall - are all of the extra bubbles necessary?

Are some DWC guys essentially running a semi-aeroponic setup? I see a lot of guys with multiple airstones / pumps for a 5 gallon bucket. The water has easily reached 100% oxygen saturation - by adding excessive bubbles are they essentially creating an aeroponic setup without misters by having the roots swimming in bubbles?

Does a true DWC setup rely solely on dissolved oxygen in the water? If that is the case, wouldn't a small 5 gallon air pump and airstone be more than adequate to maintain 100% oxygen saturation in the water and hence a "true" DWC setup?

I hope that all made sense. Please ask questions if I am un-clear or confusing.

as far as I understand the roots need to breathe basically. the more oxygen the better as far as Im concerned but you can get by with one 6in stone in a 5g pail if need be. I feel the more air the more nutes and water the roots can process and it helps to keep a balanced solution in the tank. I also feel it helps to prevent any kinds of bad stuff from forming in the res. I am not by any means stating that this is fact but how I tend to interpit the whole Idea. it also helps prevent your roots from drowning do to lack of oxygen, at what percentage of air this actually happens I have no idea maybe someone else will chime in and give us the scientific reasoning. I do wonder myself as I feel I had a little overkill going on by running 8 10in stones off two pumps in my 14g tote. but the growth was preatty amazing. I even did what they call an airbath every couple of days thats when you just drain the tank for about ten minutes and then just refill it with the same solution. at one point I had 2in of growth in one day after an air bath.

polishfalcon420 said:

as far as I understand the roots need to breathe basically. the more oxygen the better as far as Im concerned but you can get by with one 6in stone in a 5g pail if need be. I feel the more air the more nutes and water the roots can process and it helps to keep a balanced solution in the tank. I also feel it helps to prevent any kinds of bad stuff from forming in the res. I am not by any means stating that this is fact but how I tend to interpit the whole Idea. it also helps prevent your roots from drowning do to lack of oxygen, at what percentage of air this actually happens I have no idea maybe someone else will chime in and give us the scientific reasoning. I do wonder myself as I feel I had a little overkill going on by running 8 10in stones off two pumps in my 14g tote. but the growth was preatty amazing. I even did what they call an airbath every couple of days thats when you just drain the tank for about ten minutes and then just refill it with the same solution. at one point I had 2in of growth in one day after an air bath.

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I guess that is my question.

Is a 6" stone adequate for "true" DWC reservoir? From what I have read the answer is yes, because that one stone will provide and maintain 100% oxygen saturation in the water / nute solution as long as it is making bubbles.

8 - 10" stones in a small tote seems to mimic aeroponics more than a "true" DWC application. I say this because the water is certainly saturated with oxygen, but at the same time the roots are no longer swimming in oxygenated water - they are swimming in an air / water medium that mimics aeroponic growing more than DWC. It appears to me to be a "simple" way to get the roots in a HEAVILY oxygenated environment (aeroponics) without having to deal with draining / clogged misters which can sometimes be problematic.

?

I was hoping to spark a good exchange of ideas. Guess not.

tnrtinr said:

I was hoping to spark a good exchange of ideas. Guess not.

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Can't speak on aeroponics, but in DWC, you want as many bubbles and as much oxygen in the water as you can get.

Simple as that - in all honesty, your post seems to be making things more complex than they need to be.

Whatever system you choose, good luck to you.

6 CO2 + 12 H2O + light → C6H12O6 + 6 O2 + 6 H2O
carbon dioxide + water + light energy → glucose + oxygen + water

jesus of Cannabis said:

6 CO2 + 12 H2O + light → C6H12O6 + 6 O2 + 6 H2O
carbon dioxide + water + light energy → glucose + oxygen + water

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But photosynthesis is above ground; I believe the OP is referring to what happens in the root area.

Bob Smith said:

Can't speak on aeroponics, but in DWC, you want as many bubbles and as much oxygen in the water as you can get.

Simple as that - in all honesty, your post seems to be making things more complex than they need to be.

Whatever system you choose, good luck to you.

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What is the point of having more bubbles than what is necessary to saturate the water with oxygen?

something else to consider is...

The saturation point of dissolved oxygen is inversely related to the temperature of the water. Colder res temps = Increased levels of dissolved oxygen.

"
Most growers are familiar with the need to have some form of aeration in their nutrient solution - whether they be in a recirculating or a media based system. In NFT systems, this is often accomplished with the use of an air pump or by allowing the nutrient to fall back into the reservoir thus introducing oxygen. However, the effect of temperature of the solution on the dissolved oxygen levels and on root respiration rates also needs to be taken into account. As the temperature of your nutrient solution increases, the ability of that solution to 'hold' dissolved oxygen decreases. For example, the oxygen content of a fully aerated solution at 10C (50 F) is about 13ppm, but as the solution warms up to 20 C (68 F) the ability of the liquid to 'hold' oxygen drops to 9 - 10ppm, by the time the solution has reached 30 C (86 F), then it's only 7ppm.
While this may not seem like a huge drop in the amount of dissolved oxygen, we have to remember that as the temperature of the root system warms, the rate of respiration of the root tissue also increases and more oxygen is required by the plant. For example, the respiration rate of the roots will double for each 10C rise in temperature up to 30C (86 F). So the situation can develop where the solution temperature increases from 20 - 30C (68 - 86 F) during the day, with a mature crop, then the requirement for oxygen will double while the oxygen carrying capacity of the solution will drop by over 25%. This means that the dissolved oxygen in solution will be much more rapidly depleted and the plants can suffer from oxygen starvation for a period of time."

found this on another site......

Stgeneziz said:

something else to consider is...

The saturation point of dissolved oxygen is inversely related to the temperature of the water. Colder res temps = Increased levels of dissolved oxygen.

"
Most growers are familiar with the need to have some form of aeration in their nutrient solution - whether they be in a recirculating or a media based system. In NFT systems, this is often accomplished with the use of an air pump or by allowing the nutrient to fall back into the reservoir thus introducing oxygen. However, the effect of temperature of the solution on the dissolved oxygen levels and on root respiration rates also needs to be taken into account. As the temperature of your nutrient solution increases, the ability of that solution to 'hold' dissolved oxygen decreases. For example, the oxygen content of a fully aerated solution at 10C (50 F) is about 13ppm, but as the solution warms up to 20 C (68 F) the ability of the liquid to 'hold' oxygen drops to 9 - 10ppm, by the time the solution has reached 30 C (86 F), then it's only 7ppm.
While this may not seem like a huge drop in the amount of dissolved oxygen, we have to remember that as the temperature of the root system warms, the rate of respiration of the root tissue also increases and more oxygen is required by the plant. For example, the respiration rate of the roots will double for each 10C rise in temperature up to 30C (86 F). So the situation can develop where the solution temperature increases from 20 - 30C (68 - 86 F) during the day, with a mature crop, then the requirement for oxygen will double while the oxygen carrying capacity of the solution will drop by over 25%. This means that the dissolved oxygen in solution will be much more rapidly depleted and the plants can suffer from oxygen starvation for a period of time."

found this on another site......

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I have seen similar information but in a small res system the pump / airstone are able to replace oxygen at the same rate that the plant can absorb it. More bubbles are not going to change that replenishment rate that was more than adequate for a solution with a higher saturation limit.

how do you know if the res is fully saturated? have you seen different results from using different amounts of air-stones in a given volume of water? I've seen positive changes from adding a more adequate air source to my res.(but that could just mean it was off to begin with)

Stgeneziz said:

how do you know if the res is fully saturated? have you seen different results from using different amounts of air-stones in a given volume of water? I've seen positive changes from adding a more adequate air source to my res.(but that could just mean it was off to begin with)

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Assuming that you match or exceed the volume of your pump to the size of container you can easily reach oxygen saturation.

What size pump vs. what size res were you using to begin with and what did you change it to?

at the time, a 16gal res, one dual outlet wal-mart aquarium pump (i think 2800 cc) with one 12" stone, and one 10" stone. I doubled that later on, and had positive results. It was a pretty deep tub, and the extra bubbles were also beneficial to splash the young roots, before I got around to using feeder tubes.(but that also supports what you were saying earlier about aero an wat not) =)

Stgeneziz said:

at the time, a 16gal res, one dual outlet wal-mart aquarium pump (i think 2800 cc) with one 12" stone, and one 10" stone. I doubled that later on, and had positive results. It was a pretty deep tub, and the extra bubbles were also beneficial to splash the young roots, before I got around to using feeder tubes.(but that also supports what you were saying earlier about aero an wat not) =)

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hey brother. good question. no need for extra money on a heavy duty airpump if not needed. now, in all our minds, if you need air bubbles in order for root growth, more bubbles the better. i am no scientist, although i wish i was sometimes growing mj. i wish i could tell you what the minimum amount of bubbles needed in each size res, but i cant. maybe someone here can. good luck. be safe, happy growing