How many bubbles for a DWC?

Whats the rule of thumb here? I mean I get the more bubbles the better but for multiple resivoirs or a few big ones can you just use a 20W Air Pump or does each and every plant need its own air pump? If anyone has pictures of their pumps on/bubbles going that would be nice so I can see and compare it to mine. Thx 4 any tips.

The bigger the pump the more outlets it will have. A 20w air pump should have 6-8 outlets on it meaning you can run 8 different airstones. Each plant does not need it's own pump, however it is better to use more then one pump for your system just in case one of them stops working (which it will). For example, a 12 bucket re-circulating DWC could either use three different 4 outlet pumps and have a line run to each bucket, or a 4 outlet and an 8 outlet. That way if and when one of them goes out, your plants will still be getting the oxygen they need.

Ok, that sounds good but does it need to be bubbling like crazy or is it just important that there are bubbles in there? My current set-up is two 30-gallon resivoirs that are filled with 20 gallons and the roots are starting to touch the water. I've got my 20w air pump hooked up with a line going into each rez that supplies bubbles to 3 of the 4 sides. Is this enough or do I need more? I'll take another pic to show the amount closer up, but I won't have it up until tomorrow.

one is just fine
but the more the better
i like to see some much that it looks like a sprayer is in there

Too many bubbles can actually damage the root systems. You want the water moving but not violently. How many outlets does that 20w pump have? It should have enough airflow to where you could run another line to each res and get an airstone on the side where there isn't any bubbles. You will still be fine as there will be plenty of dissolved oxygen in the water with what you have going now but a little more wouldn't hurt anything.

If you're trying to maximize the area that is covered by the bubbles and buying a bigger air pump is not an option - a simple and cheap cure is a gang valve. it basically splits the outlets of any size air pump. I couldn't say how much air it will spit out - but i'm sure it woudl be fine.

Mr. Na$ty said:

Too many bubbles can actually damage the root systems. You want the water moving but not violently. How many outlets does that 20w pump have? It should have enough airflow to where you could run another line to each res and get an airstone on the side where there isn't any bubbles. You will still be fine as there will be plenty of dissolved oxygen in the water with what you have going now but a little more wouldn't hurt anything.

Click to expand...

Wrong and wrong. Krusty buckets have been using over 20lpm ---per plant--- for over 10 years, 10lpm if you add waterfalls and rdwc. Less air than that is less than ideal. Your pump shouldn't actually be used for more than one or two plants if you are trying to go for ideal and really big trees.

And yes one big quality pump or regenerative blower is better than a bunch of small ones in my opinion and reliable enough you probably wouldn't even need a backup if you spend the money on the good ones.

The small ones can't drive the same pressures at the same depths.

OregonMeds said:

Wrong and wrong. Krusty buckets have been using over 20lpm ---per plant--- for over 10 years, 10lpm if you add waterfalls and rdwc. Less air than that is less than ideal. Your pump shouldn't actually be used for more than one or two plants if you are trying to go for ideal and really big trees.

And yes one big quality pump or regenerative blower is better than a bunch of small ones in my opinion and reliable enough you probably wouldn't even need a backup if you spend the money on the good ones.

The small ones can't drive the same pressures at the same depths.

Click to expand...

I use one of these, and I get spectacular results $64.95

DUAL DIAPHRAGM AIR PUMP
Four Valve High Output Air Pump

The General Hydroponics Dual Diaphragm air pump is extremely quiet and the only air pump in the world manufactured exclusively for hydroponics systems. This high output pump has four adjustable ¼” outputs that can be teed off to power up to twelve air driven hydroponics growing systems such as the WaterFarm. In addition, growers who use our Dual Diaphragm air pump can use it to reliably oxygenate their reservoir with air stones.
AC POWERED MODEL
With standard 3-prong AC power cord
AC 120V, 0.2 amps
3 psi, 320 gph (20 l/min)

CLOSETGROWTH said:

I use one of these, and I get spectacular results $64.95

DUAL DIAPHRAGM AIR PUMP
Four Valve High Output Air Pump

The General Hydroponics Dual Diaphragm air pump is extremely quiet and the only air pump in the world manufactured exclusively for hydroponics systems. This high output pump has four adjustable ¼” outputs that can be teed off to power up to twelve air driven hydroponics growing systems such as the WaterFarm. In addition, growers who use our Dual Diaphragm air pump can use it to reliably oxygenate their reservoir with air stones.
AC POWERED MODEL
With standard 3-prong AC power cord
AC 120V, 0.2 amps
3 psi, 320 gph (20 l/min)

Click to expand...

Wow ClosetGrowth, your journal is amazing. I'm about to start my journal right now and I'd be very appreciative if you'd check in on it and give me some pointers. After seeing yours I'm rethinking a few things, I like how you experiment too, I do the same. Next time I get $65 I don't have anything to spend on, I'm buying the Dual Diaphragm straight away!!!

Dude, 70lpm same price, don't even think about that other I'm sure it's fine but that's not the money pump.

http://www.hydrofarm.com/pb_detail.php?itemid=7646

OregonMeds said:

Dude, 70lpm same price, don't even think about that other I'm sure it's fine but that's not the money pump.

http://www.hydrofarm.com/pb_detail.php?itemid=7646

Click to expand...

The one I've got looks like that, but its bigger (I think) and it doesnt have a handle. I'll add pics of it, and yes I have a gang valve with 6 outlets but I only have 2 with air flowing since I only have 2 rezs

Alpha Prime said:

The one I've got looks like that, but its bigger (I think) and it doesnt have a handle. I'll add pics of it, and yes I have a gang valve with 6 outlets but I only have 2 with air flowing since I only have 2 rezs

Click to expand...

There are many pumps that look identical to that, but some are physically larger even though they flow significantly less air/less wattage. You'll have to show the label or at least try to find the wattage. Oh and you really should never only run two outlets off a big sucker like these, use as many stones/soaker hose/whatever as it takes to flow smoothly and with the lest heat build up in the pump so you get some life out of the thing or you can burn it up restricting it.

Using ao ir pumps is old school. just get a good needle wheel pump. Smaller bubbles of a much, much larger number so higher you will have water with a higher DO level than when using air stones or just a pump, plus good water circulation from the pumps out put. Water is drawn in through a venturi valve which pulls in air. The pumps impellor chops the bubbles up into very small bubbles. The small bubbles mean more surface area so a higher percentage of the oxygen is transferred to the water.

For med/big systems get a Alita air pump or similar brand. They aren't cheap but flat out the best for the job. I got the AL-60 running 6 15 ga. tubs with 4 ecoplus med. sized round air stones per tub no problem.

fatman7574 said:

Using ao ir pumps is old school. just get a good needle wheel pump. Smaller bubbles of a much, much larger number so higher you will have water with a higher DO level than when using air stones or just a pump, plus good water circulation from the pumps out put. Water is drawn in through a venturi valve which pulls in air. The pumps impellor chops the bubbles up into very small bubbles. The small bubbles mean more surface area so a higher percentage of the oxygen is transferred to the water.

Click to expand...

I was very interested in this idea the first time you mentioned it, but still haven't had a chance to test it.

Is this theory you are talking about or has this technique been used before? If so link?

I did a lot of research after you said it before and looked up protein skimmers, then read about various methods they use to aerate other than needle wheel pumps and found spray injection. Apparently it allows more water flow, aerates even better than any other method, and with less power thus less heat.

What do you think about that idea?
Spray injection dwc?

And I also looked up the needle wheel pumps and could use your help determining the minimum wattage cheapest (but completely capable) pump just to test this for a single big ass tree. I have a danner 7 I could get a fractionating impeller for I guess, is that equivalent? The flow on the needle wheel pumps is low and I'm aiming for 400gpm at 3' with superior aeration than even a krusty bucket. (20lpm+ through 4 big stones just for one tree) I need more aeration than anything posted before but just for the one test tree.


Or I read about modding the impellers on any pump, not sure I'd want to bother though.

At what point does water become saturated with oxygen and unable to hold more? Likewise, what's the point of diminishing returns re: a plant's ability to utilize oxygen in water? Is it true that roots in a res with just a single airstone are somehow deprived?

I have no idea. I always thought a dwc res required little in the way of oxygenation and the hard job for the bubbles was sufficient splashing into the airspace. My only evidence is that since I've been using the high bubble action approach, I have 3 times the bubbles/oxygenation around the roots in the water, but see no difference in the plant's growth or health.

I'm not at all concerned with how much air the water can hold or oversaturating, Absolutely I want oversaturated but it's really about the movement and flow too. As long as the air doesn't blow all the water out of the container or the flow is so great it shreds or kills roots.

Tell us your thoughts on that Fatman. Keepoing in mind my design goal is most aeration possible/least heat. Boiling the roots in cool water. This plan is aimed at 4 of the new 1500w HPS vertical lights per plant and to support a root mass of maybe 25 gallons or even more up to possibly 55 gallons.

OregonMeds said:

I was very interested in this idea the first time you mentioned it, but still haven't had a chance to test it.

Is this theory you are talking about or has this technique been used before? If so link?

I did a lot of research after you said it before and looked up protein skimmers, then read about various methods they use to aerate other than needle wheel pumps and found spray injection. Apparently it allows more water flow, aerates even better than any other method, and with less power thus less heat.

What do you think about that idea?
Spray injection dwc?

And I also looked up the needle wheel pumps and could use your help determining the minimum wattage cheapest (but completely capable) pump just to test this for a single big ass tree. I have a danner 7 I could get a fractionating impeller for I guess, is that equivalent? The flow on the needle wheel pumps is low and I'm aiming for 400gpm at 3' with superior aeration than even a krusty bucket. (20lpm+ through 4 big stones just for one tree) I need more aeration than anything posted before but just for the one test tree.


Or I read about modding the impellers on any pump, not sure I'd want to bother though.

Click to expand...

The spray injection system is really just a version of a Beckett skimmer. There are huge numbers i of DIY sites on making a Beckett skimmer. The injector is made out of PVC pipe fittings with a little modification. Inside the fittings a Beckett fountain sprayer is used.
There are loads of sites with do directions to build Beckett skimmers on reef aquarium forums. You would just need to build the injector portion. They are made for external pumps but could be use with a submersible with just just a few more small fittings to extend the air inlet and the inlet control valve so that it is out side the reservoir above the reservoir water line.

If you already have a submersible pump and you talking just one reservoir with one tree then I would just buy a venturi only to use with th your pump. You would need to control the amount of air going into the venturi with a simple air line valve as use with aquariums. The Beckettfountain heads are quite cheap as they are jus cheap vacumn formed plastic. This link is a bit expensive. Yhttp://www.ponds2go.com/Beckett_Fountain_Heads_7113810_p/bec1420.htm You should be able to get them for $15 to $20 depending on size.

Larger ventturis are used quite often with commercial NTF and aero systems. Venturis are easy to make in larger sizes out of simple acrylic tubing. Just takes a heat source to heat the tubing so as to stretch it into an hourglass shape and a drill to drill a few holes. It is imply made with two tubes. One must be sized just small enough to slip inside of the larger tube. Typically they do not use needle wheels just a standard pump and the venturis, but with the venturis used on the pumps exit side rather than the inlet side. It produces a smaller bubble than air stones but not as small as a needle wheel pump with the venturi on the inlet. The home made ones work better than the store bought ones.

Thanks man, much appreciated.

Venturi on the outlet side? Ok I'm going to have to look into that one. It seems like that wouldn't even work off the top of my head, but I believe you. Must be simple, just seems counter-intiutive given positive pressure on the output side.

Ok, I have more reading to do...

A true venturi is when a choked flow increases the speed of the fluid it goes through a smaller hole). The pressure at this area will in fact be lower than the unchoked area, allowing a vacuum to be created.

Another way to look at it is; Flow = Velocity * Area (F=V*A), area is the area of the pipe at different dimaters. V=F/A As the flow will stay the same (theoretically), if you increase the area of the pipe (Throat) the velocity (speed) will decrease, if you decrease the area of the pipe the velocity will increase. This causes the pressues to differ on each side of the smallest part of the throat and this pressure difference creates the vacumn.