RDWC without air pumps?

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George2324

Well-Known Member
I've seen some people mention that circulation alone is enough to aerate the water:

I'm just wondering at what point can I get away with no air pumps?

If I have a 300l RDWC system and a 4000 lph pump circulating the water that makes the water do a complete rotation 13.3 times an hour or every 4.5 minutes.

The air bubbles popping in my system are causing way to much noise in the rooms below so I'm trying to design a system that can work without the air pump. The water does splash into the control bucket causing a lot of aeration too if that helps.

I currently only have a rotation every 30 minutes as I didn't make the connecting pipe between buckets large enough. I'm gonna upgrade them to 2 inch pipe and the pump to 4000 lph if that's enough for aeration

Anyone got any experience with doing this?
 
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George2324

Well-Known Member
newguy123 said:
I'm sure it will work.
Plant don't absolutely need the air pumps, its just better.

Also, the powerful air pumps are damn noisy but the weaker ones are not. You could get this one for 15$. I have 1 of them for each of my 2 dwc and they do the job. There are more powerful silent ones too.
https://www.amazon.com/dp/B01EBXI7PG/ref=psdc_2975471011_t2_B002JPEVMC
Click to expand...
I'd need like 30 of those pumps tho for the DWC system I've just setup so I'd rather go with a system that recirculates so fast it stays oxygenated without any air pumps at all.

I've seen posts by some people saying they do it and call it high flow RDWC but I can't find any mention of the flow, pipe size or circulations per minute so left me unable to figure it out

I'm considering a 16000 lph pump which would get me around 14500 lph due to lift to create oxygenation...

400l water volume which is 36.25 rotations and hour.
And a rotation every 1 minute 35 seconds.
I wonder if this is enough for maximum oxygenation
 
projectinfo

projectinfo

Well-Known Member
Keeping your water at the right temp is more important than how much dirty air you throw into it.

Colder water holds more dissolved oxygen.

You over power your pump and heat up your res. It doesnt matted how much dirty air or sloshing you do to it haha

Simply running your water will be more than enough oxygen.

You can even put it on a cycle timer if it gets your water too warm. Minute on minute off. Type of thing try some times out befor getting a Chiller
 
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George2324

Well-Known Member
I already have a chiller and water temp kept at 18c water pump is not submerged so heat not an issue. Just trying to establish what flow rate would oxygenate the water enough
 
projectinfo

projectinfo

Well-Known Member
George2324 said:
I already have a chiller and water temp kept at 18c water pump is not submerged so heat not an issue. Just trying to establish what flow rate would oxygenate the water enough
Click to expand...

As long as your water drops back into your tank your doing enough.

Like a waterfall

Or a runoff hose from a flood table. Know what I mean?
 
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George2324

Well-Known Member
If it drops into my tank and takes a whole hour to circulate around and come back though that oxygen is going to deminish before it gets to the last pot.

So I'm trying to find out how fast I need it to circulate as I don't know how fast my 2 inch bulkheads will allow water to drain to next bucket before overflowing. I might not be able to do 14500 lph as it may overflow my buckets so if i need 14500 lph I'll have to update my bulkheads to larger diameter
 
gr865

gr865

Well-Known Member
Have you considered passive oxygenation? I switched from using an air pump and stones due to the heat created by the air passing through the solution and pH fluctuations.
I do not run RDWC, but I do run a drip in coco and I recirculate from a lower 16 gallon rez to a 14 gallon upper main rez. This rez has a stand pipe that drains back to the lower rez via gravity.
Both rez's taken just before lower rez cycles to the upper rez.
20180215_101751.jpg
The 1/2 inch line in the middle is the line from the lower rez for pumping into the upper rez. The 3/4 inch line on the left is the feed line to the plants (red line pointing down is the anti syphon line). The 3/4 inch line to the right is the recirculation line down to the lower rez.
20180225_114205.jpg
The 1/2 inch line from the standpipe in the upper rez to the lower rez is cut short just inside the rim of the lower rez to create a splashing action in the lower rez, similar to the way a waterfall oxygenates the waters below.
20180224_102456 (2).jpg

For my DTW system this provides fully oxygenated solution. The recirculation runs from the time the lights go out until around 45 minutes prior to lights on. This gives me time to do the pHing adjustments as needed. It also recirculates in between the 3 water cycles for 15 minutes to keep the upper rez full and provide some extra O2 to the system.
One thing I have found over the yrs is that if I add nute solution in the AM after lights out and recirculate for the approx 12 hrs prior to lights on the solution stabilizes. Doing this prior to the evening pH adjustment the solution retains its pH, throughout the drip cycle, with very little fluctuation.
I am not sure this would work with your system but it is very successful for me.
Good luck Bud,

GR
 
projectinfo

projectinfo

Well-Known Member
gr865 said:
Have you considered passive oxygenation? I switched from using an air pump and stones due to the heat created by the air passing through the solution and pH fluctuations.
I do not run RDWC, but I do run a drip in coco and I recirculate from a lower 16 gallon rez to a 14 gallon upper main rez. This rez has a stand pipe that drains back to the lower rez via gravity.
Both rez's taken just before lower rez cycles to the upper rez.
View attachment 4096139
The 1/2 inch line in the middle is the line from the lower rez for pumping into the upper rez. The 3/4 inch line on the left is the feed line to the plants (red line pointing down is the anti syphon line). The 3/4 inch line to the right is the recirculation line down to the lower rez.
View attachment 4096146
The 1/2 inch line from the standpipe in the upper rez to the lower rez is cut short just inside the rim of the lower rez to create a splashing action in the lower rez, similar to the way a waterfall oxygenates the waters below.
View attachment 4096152

For my DTW system this provides fully oxygenated solution. The recirculation runs from the time the lights go out until around 45 minutes prior to lights on. This gives me time to do the pHing adjustments as needed. It also recirculates in between the 3 water cycles for 15 minutes to keep the upper rez full and provide some extra O2 to the system.
One thing I have found over the yrs is that if I add nute solution in the AM after lights out and recirculate for the approx 12 hrs prior to lights on the solution stabilizes. Doing this prior to the evening pH adjustment the solution retains its pH, throughout the drip cycle, with very little fluctuation.
I am not sure this would work with your system but it is very successful for me.
Good luck Bud,

GR
Click to expand...
This
 
G

George2324

Well-Known Member
I can't really implement anything like yours when I have 30 DWC buckets I need aeration all through the day as the roots are directly in the solution.

If circulation does the job it would be the easiest solution for me
 
projectinfo

projectinfo

Well-Known Member
Then over power it and go from there man. You can buy a dimmer or a ball valve to dial it back if it's too much
 
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George2324

Well-Known Member
Yeah those are the ones I mentioned above where people talk about it being possible but don't really give the amount of circulations per hour etc needed to know at what point it becomes possible. I'll upgrade my pump to 145000 lph the biggest I can get and see how to goes from there. Might have to just add multiple bulk heads to allow multiple flows of water
 
projectinfo

projectinfo

Well-Known Member
George2324 said:
Yeah those are the ones I mentioned above where people talk about it being possible but don't really give the amount of circulations per hour etc needed to know at what point it becomes possible. I'll upgrade my pump to 145000 lph the biggest I can get and see how to goes from there. Might have to just add multiple bulk heads to allow multiple flows of water
Click to expand...

Make sure to document and post so the next guy with your question can find your conclusion :)
 
gr865

gr865

Well-Known Member
@ George, 145,000 lph is 38,304 gph.
I think you meant 14,500 lph which is 3,839 gph
I am running a ECO 1056 which is 1083 gph. Your pump if is does 3839 is nearly 4 times my pump. With that, you could do a multi outlet manifold and create a shit load of dissolved O2.

Yes keep us posted!
 
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George2324

Well-Known Member
gr865 said:
@ George, 145,000 lph is 38,304 gph.
I think you meant 14,500 lph which is 3,839 gph
I am running a ECO 1056 which is 1083 gph. Your pump if is does 3839 is nearly 4 times my pump. With that, you could do a multi outlet manifold and create a shit load of dissolved O2.

Yes keep us posted!
Click to expand...
Yes I meant 14500 lph.

The system contains around 400-500l of water though so the rotation depends on the total volume.

Do you have any example of a multi outlet manifold?
I don't understand what you mean.

I have a control bucket where the pump dumps water from the return line. I'm hoping the fast current alone creates all the DO
 
gr865

gr865

Well-Known Member
MIne has one point of discharge.
20180224_102456 (2).jpg

You could with the amount of solution you are using, approx 130 gallon, do a manifold to increase your discharge points into your rez. At that rate of return has to produce considerable amount of pressure, so you could maybe use more entry ports off the manifold.
20180228_074456 (2).jpg

Hope this clears this up.

GR
 
Last edited:
G

George2324

Well-Known Member
gr865 said:
MIne has one point of discharge.
View attachment 4097785

You could with the amount of solution you are using, approx 130 gallon, do a manifold to increase your discharge points into your rez. At that rate of return has to produce considerable amount of pressure, so you could maybe use more entry ports off the manifold.
View attachment 4097784

Hope this clears this up.

GR
Click to expand...
Ah right I get you. Do you use air pumps in yours or do you have enough DO from the flow?
 
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