DWC Buckets and Dissolved Oxygen

[Throwgar]

I was just putting together the plans for a 24 bucket DWC system. I see all of the setups on this site using air stones in each bucket. Since this is a recirculating DWC, and the nute solution will (rather quickly) end up back in the reservoir, could I just focus on oxygenating the res, and skip the air stones in the buckets? Has anyone tried this?

 

[Guest]

Yes you can airate the resivoir and not use airstones in each bucket. Your design can also incorporate a waterfall effect when recirculating, thur airating the nutrient mix even more when entering the buckets. IMO with dwc, the more disolved oxygen in the mix the better.

 

[Raphael]

Yes you can airate the resivoir and not use airstones in each bucket. Your design can also incorporate a waterfall effect when recirculating, thur airating the nutrient mix even more when entering the buckets. IMO with dwc, the more disolved oxygen in the mix the better.

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

Put a mark where your current res temps are and draw a straight line through the 100% saturation mark through the third line to see the different levels of dissolved oxygen at different temps

"
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."


http://www.quickgrowsouth.com/gardening_articles/dissolved_oxygen_levels.html

 

[Two12sKnockin]

you got some good advice from the above posters.

however I want to say I think anyone who is truly serious about dwc will tell you you're a fool to try to do it without stones in each bucket. no offense I just dont know how else to convey the gravity of this issue as I see it - dont take that to heart.

whats the advantage of your question? why would you not aerate each bucket?

dwc is an incredible system but only when it's done right.


it's not very expensive to add very high output air pumps and if you're running 24 buckets I dont get why you couldnt afford commercial pumps.. if its an issue of finances just scale down your op this time so you can get all the proper equips and next time you'll be able to add extra buckets, should you have the need and desire to do so.

good luck

 

[Throwgar]

It's actually an issue of convenience. I've been running DWC for over 10 years, but I've had 4x10 site storage bins, each with a couple of air stones, which makes it more of a bio bucket than anything else.

With the recirculating DWC buckets, it really feels more like a NFT system, with the nutrient solution only leaving the main res for a minute or so. If the res is saturated with DO, wouldn't the stones in each bucket be superfluous if the nute solution is already at max DO?

 

[Raphael]

If the res is saturated with DO, wouldn't the stones in each bucket be superfluous if the nute solution is already at max DO?

As long as the air was able to completely re-saturate all the water before it leaves the reservoir.

The plants will be using up the DO in each bucket, meaning the drain water has much lower DO in it so the res won't be just maintaining the levels of DO, but constantly re-saturating the return line.

I am going to get a DO meter soon so I can see how much a flowering plant uses

cheers

 

[Two12sKnockin]

You're gonna need a 633 gph pump or thereabouts to recirc. I cant really imagine you being able to pull this off, saturating fast enough? seems extremely unrealistic to me, and you have way too much at stake in my very humble opinion to justify taking that kind of risk

I gotta tell you man. convenience? I'll bet 20 bucks right now that you regret this if you go forward with it. and if the stars align and im wrong well you dont need an ID to pick up a western union so just have some chickenhead grab the dub spot for mr paul revere =p

edit: you are right however, RDWC is a DWC/NFT hybrid mas o menos

 

[Raphael]

and if the stars align and im wrong well you dont need an ID to pick up a western union so just have some chickenhead grab the dub spot for mr paul revere =p

lol I think I'm just high but this sentence has had me laughing for 3 minutes trying to figure it out.

"If I'm wrong I'll send you a money transfer via Western Union because you don't need an ID to pick a transfer up (really?) so just have some chickenhead get the money look for a guy on a horse?"

-confused raffy

EDIT: sorry for the offtopic post, I finally got it now

 

[Two12sKnockin]

lol, its one of those deals where if you didnt get it its best to just move on. but to translate:

if you dont need an ID obviously the name is irrelevant.

you seem quite intelligent so i'll leave it at that and lets not get this poor guy's thread too off topic

 

[Throwgar]

Does anyone know how long it takes to reach max saturation (DO)? I was always under the assumption that is was nearly instant, but if not, I can see how the air stones in the buckets would be necessary. Also, along the same lines, how quickly do the root systems uptake oxygen?

I'd need 12 air pumps (48 stones), and I only have 4 at the moment. My bud bunker tapped my funds, so that's why I'm wondering if I could forego the individual bucket's air stones.

You're probably right, why risk it, it can't hurt to have extra DO capacity.

 

[Lightning Bug]

My buckets are the only ones I have seen with a 'waterfall' in each bucket, if you know of others I would appreciate a link.

I ran my first grow in this bucket system with no airstones, no problem. I don't have a DO meter anymore but do have some experience in this field and I am pretty sure my design gets me pretty close to atmospheric oxygen levels (saturation).

I added airstones for later runs but can't say that they made any difference. I mainly added the stones to help with the popping action to make the lids wet and help with early growth before the roots hit the water.

Airstones are cheap insurance in case of system problems (not that I have had any) and more air can't hurt so why not use them, they are not that much of a PITA or expensive IMO.

 

[antimatter]

why would DO be so limited by temperature ? you would think 1800 gph pumps per 5 buckets and regen blowers and aquriam pumps all combined in your res would give you a lot more oxygen.

"Temperature, pressure, and salinity affect the dissolved oxygen capacity of water. The ratio of the dissolved oxygen content (ppm) to the potential capacity (ppm) gives the percent saturation, which is an indicator of water quality. "

 

[greasehorse]

Anyone tried those 8.5 inch bubblers?

 

[Two12sKnockin]

regarding water temperature importance: to reiterate in layman's terms, colder water is capable of holding more DO. the hotter water, the less DO, which is why at 75 and up people start to get root rot - its a result of oxygen deprivation.

Throwgar, perhaps the reason you think it's inconvenient to run air pumps is because you appear to think you need 2 air pumps per bucket? is that correct? you want 48 pumps for 24 buckets?

Look at commercial air pumps. Most cheap air pumps are about 1-2 liters per minute of output. for less than 100 dollars you can get a commercial grade airpump with 110 liters per minute which has a 12 outlet manifold which you can tee off to achieve 24 outlets, one for each bucket.

I've never used 8.5 inch stones but I've used damn near everything else and the BEST are the disc shaped stones. currently using 4 inch stones. I've used the cheapo 1 inch stones but I dont think their distribution is optimal, however I HAVE gotten 6 bomb zips off a sour d vegged for 11 days and flo'd for 65 off a 1 inch airstone with optimal water temperatures.

all about DO and DO is largely about temps

 

[Raphael]

however I HAVE gotten 6 bomb zips off a sour d vegged for 11 days and flo'd for 65 off a 1 inch airstone with optimal water temperatures.

How much light was on that sour d? 11 days starting when the clone's roots were established?

Nice, +rep

 

[Sir_Nugget]

DO can be there one second and gone the next... i'd consider oxygenating each bucket with a nice waterfall or airstones. keep ur rez at 70 deg and ur plants will reward u

 

[Two12sKnockin]

Raph: 11 days from when roots hit the water. they were NOT recirculating, 6 buckets per thouwie, and with 1 inch airstones that were running off GH dual diaphram air pumps that had been teed off to supply 8 buckets each instead of 4 as per standard.

this was years ago and by my standards today that system is and was inferior. also I would have both vegged and flo'd longer but was restricted by time.

just goes to show you how big a role water temps play as my temps were a solid 67.

 

[Raphael]

Raph: 11 days from when roots hit the water. they were NOT recirculating, 6 buckets per thouwie, and with 1 inch airstones that were running off GH dual diaphram air pumps that had been teed off to supply 8 buckets each instead of 4 as per standard.

this was years ago and by my standards today that system is and was inferior. also I would have both vegged and flo'd longer but was restricted by time.

just goes to show you how big a role water temps play as my temps were a solid 67.

Very nice two12sknockin I am in the process of a similar grow currently at day 12 veg with 8 recirc 5gals under 2 600s. The link will be in my sig, don't want to hijack anymore.

Cheers

 

[antimatter]

I wonder what the ppm of dissolved oxygen is in True High Pressure Aeroponics, if you look at DWC growth vs TAP you can see that DO isn't everything so there must be a threshold of how much the roots need.

 

[Guest]

It's actually an issue of convenience. I've been running DWC for over 10 years, but I've had 4x10 site storage bins, each with a couple of air stones, which makes it more of a bio bucket than anything else.

With the recirculating DWC buckets, it really feels more like a NFT system, with the nutrient solution only leaving the main res for a minute or so. If the res is saturated with DO, wouldn't the stones in each bucket be superfluous if the nute solution is already at max DO?

It's all in how you design the system. Whichever route you take, chances are you will have the same volume of water to work with. For example, a 100 gallon resivoir. There are many ways already mentioned to airate this 100 gallons, and not one is nescesarily better than another. The one that will work the best is the one that suits your needs best. Space, budget, and preference are not always the same for each grower.

How much DO is enough? I am not a scientist, but I prefer to see many tiny bubbles spread across the largest surface area in a given bucket. With good force they are almost rumbling and each tiny air bubble explodes at the top as if it were a fireworks display.

Can you saturate a plant with too much DO? Yes, letting the buckets run dry. So long as there is sufficient water/feed/moisture, I do not think there is a point where the DO is too high in a DWC style set-up. Plants also use oxygen from the water molecules when feeding, so in a sense its availibility is endless. IMO their access to oxygen is limited to their armor.

As you can see I am not a scientist, and use words that help me relate things in my brain. The armor is only as strong as it's weakest link in the chain. The armor in this case consists of many things such as air temprature, water temprature, relative humidity, co2 concentrations, airflow, feed proportions, and the list is almost endless. Each aspect directly corresponds to another, and usually more than one if not all others!

I think of growing as a room full of multi fasceted jewels. Each jewel with amazing clarity and color. These jewels each represent a different aspect of growing. Ie. Temprature, R/H, co2, DO, ect. When they are all aligned in an optimal way, they project an amazing array of colors with infinite beauty. However if one jewel is not alinged to optimise its position, then it throws each other jewel off sending a chain reaction down the line.

Providing appropriate DO and taking advantage of all of it is two different tasks. Same goes for all of the other jewels.

Pudding anyone?