Re-examining an age old DWC question: "Can you have too much air in DWC?"

[SmokinLabrador]

I am looking at updating and expanding my RDWC setup, and one of the key factors I have been considering is how much air pump & stone is needed per plant. The conventional wisdom was that the amount of air needed was only enough to reach the max Dissolved Oxygen level for the temp of your water. Tests have shown that this can be accomplished with minimal pump and air stone requirements. However, in my research regarding the subject, I have found several people that have suggested that reaching Max DO level is only one function of the air pump/stone in a DWC setup, and a minor one at that. These people have proposed that the roots are only absorbing something along the lines of 1% of their Oxygen via the water, and that a much larger amount of Oxygen is being absorbed via direct contact between the roots and the bubbles put off by the air stone. If this is true, it would make a solid case for using as large (and efficient) of an air pump and stone as possible, in order to increase the amount of bubbles and decrease their size, thereby maximizing the surface area of bubble from which the roots can draw their Oxygen.

Along these lines of thought, I would like to re-examine if there is such a thing as "Too Much" air in a DWC based setup. It seems much has evolved in even the past 6 months, much less the several years since most of the posts I can find on the subject. I would really like to hear the thoughts of those who are running "larger" pumps and stones, and what their experience has been in regards to the benefits of doing so. To give an example, I currently run 2 Whisper "60 gallon" pumps (whatever those work out to in volume, Tetra doesn't give the spec but they aren't much), and a 60 liter per minute pump, with 3 18" bubble curtain style airstones per plant (they are in totes), and one of the same airstones in my res. I am looking to move to 5 gallon buckets, and run a single 9" FlexAir diffuser per bucket. These diffusers max out at 5 cfm of air, which would require a pump in the range of 141 liters per minute PER BUCKET to max out the diffusers. This is obviously a huge increase, and I'd like to find out if such an increase would pay dividends. I would love to run a side by side with one of these setups vs a normal airstone and pump, but I lack the space, funds, or time.

So, what say you all? Is anyone here pushing the upper limits of air supply to your roots, and is it paying off for you?

 

[HSA]

SmokinLabrador: Pushing the limits of air supply would be Aeroponics but to quote one of our hydro instructors at school, "Your plants need a lot more oxygen than they do water for their processes and they get it from the air." When I grow in dirt I use a lot of Perlite to aeriate the soil and in DWC I have two big fat round air stones in each tub and my plants are always happy. In hydro that's called 'super charging' your plants and when they're bigger and growing more vigorously you'll know it's working. You might want to RTFB
1. Read: SeeMoreBud’s book, “MARIJUANA BUDS FOR LESS- GROW 8 OZ. OF BUDS FOR LESS THAN $100.”
2. Read: Jorge Cervantes’s book, “MARIJUANA HORTICULTURE THE INDOOR/OUTDOOR MEDICAL GROWER’S BIBLE.”
3. Read: Ed Rosenthal’s, “MARIJUANA GROWER’S HANDBOOK.”
4. You’ll also want to read: Mc Carthy’s book, “GROWING MARIJUANA.”
5. You should also subscribe to, “HIGH TIMES,” magazine. Each issue is chocked full of useful information. .” All these resources are very well written, well illustrated and packed with information that will answer most of your questions before you know to ask them. And I want to add a new book to the list, a 6[SUP]th[/SUP] one: “THE CANNABIS GROW BIBLE- SECOND EDITION,” written by Greg Green. It’s a match to, if not better than, the ones listed above. You might want to concentrate on Cervantes's, Rosenthal's and Green's books and "High Times" to start since they do the best coverage of hydro. Doing your homework and consulting these resources will save you and your plants a lot of anxiety and stress before you plant. These forums are great but often they can’t get the information you need to you in a timely fashion. I hope this helps. HSA

 

[VoidObject]

Along the lines of airstones

More isn't necessarily better.. there's been DO tests done that say the improved percentage is slim and sometimes actually negative. When the DO level in the water is increased you're going to have less 'bubbles' which is effectively aeroponic.

And air pumps

I agree more/better pumps is going to produce better roots because of more than DO levels. Water level is for nutrient uptake mostly, changed depending on root growth in optimal conditions.

 

[SmokinLabrador]

SmokinLabrador: Pushing the limits of air supply would be Aeroponics but to quote one of our hydro instructors at school, "Your plants need a lot more oxygen than they do water for their processes and they get it from the air." When I grow in dirt I use a lot of Perlite to aeriate the soil and in DWC I have two big fat round air stones in each tub and my plants are always happy. In hydro that's called 'super charging' your plants and when they're bigger and growing more vigorously you'll know it's working. You might want to RTFB
1. Read: SeeMoreBud’s book, “MARIJUANA BUDS FOR LESS- GROW 8 OZ. OF BUDS FOR LESS THAN $100.”
2. Read: Jorge Cervantes’s book, “MARIJUANA HORTICULTURE THE INDOOR/OUTDOOR MEDICAL GROWER’S BIBLE.”
3. Read: Ed Rosenthal’s, “MARIJUANA GROWER’S HANDBOOK.”
4. You’ll also want to read: Mc Carthy’s book, “GROWING MARIJUANA.”
5. You should also subscribe to, “HIGH TIMES,” magazine. Each issue is chocked full of useful information. .” All these resources are very well written, well illustrated and packed with information that will answer most of your questions before you know to ask them. And I want to add a new book to the list, a 6[SUP]th[/SUP] one: “THE CANNABIS GROW BIBLE- SECOND EDITION,” written by Greg Green. It’s a match to, if not better than, the ones listed above. You might want to concentrate on Cervantes's, Rosenthal's and Green's books and "High Times" to start since they do the best coverage of hydro. Doing your homework and consulting these resources will save you and your plants a lot of anxiety and stress before you plant. These forums are great but often they can’t get the information you need to you in a timely fashion. I hope this helps. HSA

Somedays I wonder if you are a person or a bot programmed with those same links as the answer to pretty much any question.

 

[BigBuddahCheese]

Somedays I wonder if you are a person or a bot programmed with those same links as the answer to pretty much any question.

I was thinking the same thing. Apparently he read the books, enjoyed them and then can't remember anything from them?

 

[SmokinLabrador]

Along the lines of airstones

More isn't necessarily better.. there's been DO tests done that say the improved percentage is slim and sometimes actually negative. When the DO level in the water is increased you're going to have less 'bubbles' which is effectively aeroponic.

And air pumps

I agree more/better pumps is going to produce better roots because of more than DO levels. Water level is for nutrient uptake mostly, changed depending on root growth in optimal conditions.

The two go hand in hand though. Without more/more efficient airstones, there is no point to a bigger air pump. Without a bigger air pump, you can't push the more/more efficient airstones to their limit, in turn making them pointless. But with BOTH... I think some serious improvements can happen.

Remember, we are pretty much taking DO and tossing it out the window as relevant, since even the least aggressive air pump/stone combo will reach max DO in a DWC environment. I do agree that we are talking about walking a fine line between Hydroponics and Aeroponics, since you would be talking about SO MUCH of the roots being exposed to air (via a ton of smaller sized bubbles) at any given time. However, I don't think this is necessarily a bad thing

 

[mike91sr]

I agree that more airflow is going to be better as long as you dont create a turbulent rootzone to the point of physical damage; and that DO has less to do with it than everyone seems to think. But as far as restrictive airstones, here's my outlook on it: I hooked up my 110lpm pump to 8x6" airstones, then one at a time closed them off. Even when I turned off the second to last stone, leaving 110lpm into just one bucket, I saw an increase in the airflow of that bucket. That tells me that a $1 airstone can flow more than 55lpm(without counting obvious flow reduction from restriction, distance, backpressure, etc). Considering the amount of people I see using a smaller air pump than me for setups with equal or greater water volume, I think that most setups would benefit from a bigger air pump long before bigger/better airstones.

And the micropore diffusers, which have been found on this forum to provide a lower DO, are also more restrictive and thus provide less airflow altogether, which would explain the resulting lower DO. Plus the smaller bubbles have a greater ability to coagulate, reducing the only possible benefit of using them in the first place. Bigger bubbles just means less surface area between water and oxygen, which slows the rate of dissolution but doesnt affect the solubility (DO related) or availability(plant related). Since we can already max out DO very easily, who gives a shit how fast the rate of dissolution is? It's not going to allow more oxygen to be dissolved anyway, and more importantly, nothing more will available to the plant, which is what we should be focused on.

 

[SmokinLabrador]

First off, I recall you posting in the thread that prompted me to make this one, so welcome, and glad to see you here

I agree that more airflow is going to be better as long as you dont create a turbulent rootzone to the point of physical damage; and that DO has less to do with it than everyone seems to think. But as far as restrictive airstones, here's my outlook on it: I hooked up my 110lpm pump to 8x6" airstones, then one at a time closed them off. Even when I turned off the second to last stone, leaving 110lpm into just one bucket, I saw an increase in the airflow of that bucket. That tells me that a $1 airstone can flow more than 55lpm(without counting obvious flow reduction from restriction, distance, backpressure, etc). Considering the amount of people I see using a smaller air pump than me for setups with equal or greater water volume, I think that most setups would benefit from a bigger air pump long before bigger/better airstones.

I absolutely agree with this part. Those cheapie airstones can do a lot more than most people think, and most folks would benefit from running a bigger pump before they would from upgrading the airstone itself. I'm looking to improve both halves of the equation.

And the micropore diffusers, which have been found on this forum to provide a lower DO, are also more restrictive and thus provide less airflow altogether, which would explain the resulting lower DO. Plus the smaller bubbles have a greater ability to coagulate, reducing the only possible benefit of using them in the first place. Bigger bubbles just means less surface area between water and oxygen, which slows the rate of dissolution but doesnt affect the solubility (DO related) or availability(plant related). Since we can already max out DO very easily, who gives a shit how fast the rate of dissolution is? It's not going to allow more oxygen to be dissolved anyway, and more importantly, nothing more will available to the plant, which is what we should be focused on.

The restrictive properties of the micropore diffusers should be able to be overcome by matching with the right size air pump, not only in volume but also in psi. The diffuser I am looking at (actually the same one discussed in the other thread) can flow a large amount of air, but I believe it can also disperse that air a lot more efficiently than a standard fish store air stone:

http://www.aquaticeco.com/subcategories/1874/FlexAir-Disc-Diffuser

I like this diffuser for multiple reasons: Diameter, flow rate, bubble size, etc. I think if nothing else, the spread of the bubbles across 75% of the bucket's diameter will help to provide more direct bubble contact with the roots.

I am a bit confused about this part of your statement:

Plus the smaller bubbles have a greater ability to coagulate, reducing the only possible benefit of using them in the first place.

If you could clarify, I would appreciate it I think you mean that the bubbles will bunch up on the roots, but with so much water movement, I have to believe that won't be an issue. I don't *think* the turbulence will be strong enough to damage the roots either, especially with the smaller (and in turn gentler) bubbles. As for surface area of the bubbles, wouldn't it be a direct factor in how much air the roots can absorb?

Man I love this board. Let's me get my think on

 

[mike91sr]

The restrictive properties of the micropore diffusers should be able to be overcome by matching with the right size air pump, not only in volume but also in psi. The diffuser I am looking at (actually the same one discussed in the other thread) can flow a large amount of air, but I believe it can also disperse that air a lot more efficiently than a standard fish store air stone:

http://www.aquaticeco.com/subcategories/1874/FlexAir-Disc-Diffuser

I like this diffuser for multiple reasons: Diameter, flow rate, bubble size, etc. I think if nothing else, the spread of the bubbles across 75% of the bucket's diameter will help to provide more direct bubble contact with the roots.

The biggest thing I'm thinking of is that, assuming you are able to perfectly match the pump flow and stone flow, it doesnt change the fact that any restriction is going to reduce flow. So regardless of how well they're matched, I feel like switching from a more restrictive disc to a less restrictive blue stone would still increase airflow and with it, oxygen availability. I do agree with you about the dispersion being better, I think the plant would benefit from the improved contact. I like the disc idea, just not the micropore part about it I guess.

Biggest disk I could find that isnt a micropore: http://www.onlinepetdepot.com/deep-blue-professional-high-performance-stone-inch-disk-p-15885.html

I am a bit confused about this part of your statement:



If you could clarify, I would appreciate it I think you mean that the bubbles will bunch up on the roots, but with so much water movement, I have to believe that won't be an issue. I don't *think* the turbulence will be strong enough to damage the roots either, especially with the smaller (and in turn gentler) bubbles. As for surface area of the bubbles, wouldn't it be a direct factor in how much air the roots can absorb?

Man I love this board. Let's me get my think on

Basically, smaller bubbles are more easily able to combine with each other. I think it may have to do with the amount of surface tension of each bubble, not 100% on that. Even if it happens, its not severe enough to prevent the bubbles from remaining visibly smaller throughout their entire 'lifespan'.

I'm not sure that smaller bubbles are any gentler on roots though, I think it may again just be the amount of dispersion that prevents 'hot-spots' of turbulence like 4 or 6" blue stones. Like a rifle and a shotgun. If you can get the spread, I don't think bubble size would change at what flow rate that damage starts to happen. And I doubt there's any reason a plant needs so much air that a 9" disc(micropore or.... macropore??) starts doing damage.

I think it comes down to testing specifics in a lab. There's plenty of studies and peer-reviewed journals that have shown a substantial benefit to increased oxygen levels(whether it be extra airflow or a purer oxygen source), but its a different amount of change between crops, different rate of diminished returns, and different maximum levels. And since there's very little research on the horticulture of marijuana specifically, we just don't know how much airflow is more than possibly consumable at any given time.

For all we know, anything over 20lpm, properly dispersed, could be totally useless to a plant of an 'average' size, and we're here chasing our tails to upgrade pumps and stones, fighting the heat created by them and dealing with the extra maintenance, setup, etc. There's definitely something to be said about circulation/turbulence in general though, as undercurrents do substantially better than traditional dwc if done properly.

And agreed, this is the kind of stuff I stick around for. I was taking gen chem and organic chem as I was starting to research hydroponics, definitely puttin it all to good use. My professors would be proud

 

[BigBuddahCheese]

I for one always blasted my air stones in dwc 2.5 gallon buckets. With more then enough pump my stones have been shearing my roots for years, always 1/4 to 1/2" root hairs in the bucket a lot of em, but never an issue I thought or think. But.. now I am dropping the pumps all around to just about the effect from a champenge(sp) glass, bubbles popping in surface and just breaking water tension, a lot less then I have been using for years.

I am thinking those roots are sheared I wonder if that hinders the growth, or the plant any way. My crops been awesome just bit longer then normal to hit the right ripeness for me, but I thought it was just the breeders time lines being short. Maybe.. we will see. So far the plant do not seem any worse for getting the oxygen shut down by over 50%.

 

[SmokinLabrador]

I for one always blasted my air stones in dwc 2.5 gallon buckets. With more then enough pump my stones have been shearing my roots for years, always 1/4 to 1/2" root hairs in the bucket a lot of em, but never an issue I thought or think. But.. now I am dropping the pumps all around to just about the effect from a champenge(sp) glass, bubbles popping in surface and just breaking water tension, a lot less then I have been using for years.

I am thinking those roots are sheared I wonder if that hinders the growth, or the plant any way. My crops been awesome just bit longer then normal to hit the right ripeness for me, but I thought it was just the breeders time lines being short. Maybe.. we will see. So far the plant do not seem any worse for getting the oxygen shut down by over 50%.

Good deal, please come back and update with results. How big were your root balls? In 2.5G buckets, I would think they would fill that space fairly quickly.

 

[BigBuddahCheese]

Good deal, please come back and update with results. How big were your root balls? In 2.5G buckets, I would think they would fill that space fairly quickly.

No I have plenty of room, they drink almost half of the water daily so the roots get air that way, kind of works out nice. I found for my plant size 4-5ft is plenty of room for roots/nutes etc.

Yes I have some time to monitor this experiment so I will report back in a bit on my findings but after two days they seem like they are drinking bit more but its been hot here and still they are healthy as always.

The last pic shows how fast my water used to flow with air I pumped in.

 

[sqydro]

i dont use any airstones in DWC the airstones do not give the roots air its the bubbles bursting and the aggitation of the surface area that allows the DO (dissolved oxygen) to saturate the water the more is not the merrier i think 16%+ can become toxic to plants, i use the method of waterfalling water into my plant sites in RDWC and i have done it in single pot DWC as well, im not gonnae say the results were better but certainly more efficent, less equptment, less expense, and the results were absolute astounding. check my sig out ul see what i mean

fast recirculation, fluming, waterfall effect. all ways to run DWC without stones pumps lines and all the shit that comes with it, just summit to think about matey! a full system running off 1 pump

 

[mike91sr]

.....the airstones do not give the roots air its the bubbles bursting and the aggitation of the surface area that allows the DO (dissolved oxygen) to saturate the water.....

I dont know where this myth comes from but it makes absolutely no sense. Ask yourself this: How is the air being pushed through the stone and into water any different than the air freefloating in the atmosphere that would allow the atmospheric oxygen to dissolve into solution, but at the same time prevent easily accessible oxygen already within the solution(bubbles) from dissolving as it contacts thousands of h2o molecules in its path?

How much surface area do you have on top of a 5gal bucket, maybe 1-1.5sq ft? Now think about tens of thousands of bubbles inside the solution, each with a surface area of around .5sq inch, how much more surface area do the bubbles have that could allow more oxygen transfer, let alone the fact that its actively moving through a solution rather than passively coming into contact with the surface?

btw, nice grow

 

[SmokinLabrador]

i dont use any airstones in DWC the airstones do not give the roots air its the bubbles bursting and the aggitation of the surface area that allows the DO (dissolved oxygen) to saturate the water the more is not the merrier i think 16%+ can become toxic to plants, i use the method of waterfalling water into my plant sites in RDWC and i have done it in single pot DWC as well, im not gonnae say the results were better but certainly more efficent, less equptment, less expense, and the results were absolute astounding. check my sig out ul see what i mean

fast recirculation, fluming, waterfall effect. all ways to run DWC without stones pumps lines and all the shit that comes with it, just summit to think about matey! a full system running off 1 pump

Grow looks awesome. No one is saying that the "normal" way (or your waterfall method) doesn't work. I know that some people like myself are always looking for ways to improve things that may already be working. Let's say I pull 10 lbs off a plant. That's fucking nuts! However, next time, I'm looking for ways to pull 10.1 lbs

 

[faller200]

I love reading all this high tech info. If nothing else it makes great entertainment.

 

[BigBuddahCheese]

I love reading all this high tech info. If nothing else it makes great entertainment.

Yup for the ones who don't understand, for the ones who have no issues with DO or plants and love the science of growing and tinkering brought upon doing this hobby enjoy it.

Glad you are so proficient at all aspects of your grow, but I hope I never am because I love the hobby more then trying to sling a quick zip to a punk kid on your street corner.

 

[Corso312]

I just bought a real nice heavy duty bin at home depot today..could not pass it up...if I had more cash I would buy a dozen of them for that price...12$ lid included, it is called a tough box 27 gallon..then bought six- 6" net pots..I am ready to get my feet wet with hydro..so my questions are... how large of an air pump should I use ? and how many air stones/ discs?...

 

[BigBuddahCheese]

I just bought a real nice heavy duty bin at home depot today..could not pass it up...if I had more cash I would buy a dozen of them for that price...12$ lid included, it is called a tough box 27 gallon..then bought six- 6" net pots..I am ready to get my feet wet with hydro..so my questions are... how large of an air pump should I use ? and how many air stones/ discs?...

I would put at least two (2" cylinder) and a decent size pump (60Lph) as that's a lot of gallons for those cheap walmart aquarium POS. That pump should run a few of those at that setup so better too much then not enough.

 

[Natey8080]

So to much air is good then?