RDWC without air pumps?

Have not used stones in yrs, to much heat and pH fluctuation.

gr865 said:

Have not used stones in yrs, to much heat and pH fluctuation.

Click to expand...

Good to know, so how many rotations do you aim for per hour to avoid air stones?

I run my system from around 6 AM to 8:45 PM, then shut it down, pH my solution and the only time it runs during lights on is to refill the upper rez.
I know you need more D0 running DWC than I do running DTW so if pH fluctuation is not an issue I would run something like hour on 30 min off. You will have to play with the timing for your situation.

GR



Share This Page

​

O, so

I am going to switch to bulk heads specifically designed for E & F

These commonly used bulk head have a built-in aerator at the outflow, which should provide ample aeration

sorry, I don't have a link for you

George2324 said:

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?

Click to expand...

Believe it or not, even though 2” might seem like a nice diameter for an RDWC bulkhead it sometimes will get clogged if you grow big enough monsters. The better you agitate the more and faster root development and it can clog.
Google “ DWC root clog” and you are sure to find at least one account of a DWC system with 2” bulkheads clogging. Many more so in the smaller bulkhead situations but at least a few in the 2” bulkhead class.
Go larger if the side of the container permits. They do go up in price exponentially (the Hayward pvc bulkheads) when you get past the 2” size. The biggest drawback but worth it for piece of mind if you choose RDWC.

Look up “Undercurrent DWC Plumbing Questions” Post #3 on this forum for one account of 2” bulkheads failing.

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...

The key to running the bit pumps is big tubing on a long run. Check what I did with mine and the air from the pump actually can cool the water. People are running the pumps with the manifold on the 6 inch tube that comes with it. run 10-20ft of it.

the big air pumps are compressing which creates heat.
the short tube doesn't allow enough time to cool.
the manifold being close heats up (enough that you cant hold it very long) and then that heat also transfers to the small tubing

@kingtitan, You are correct in you can get some cooling by running longer feed lines, but if you are pushing a large volume of air the heat is reduced a bit but will still effect the temp of the water.
Do you get pH fluctuation running air stones?

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...

If you go here, you will get an idea of specs relating to these retail/commercial kits when you click the specific model. even lists the pump flows and all.
https://cch2o.com/under-current-hydroponic-system-info/

If you want to take a look through my journal maybe that could help out too.

Now here is my thoughts. Running the pumps that fast is going to create a big flow, and much more as you get closer to each in/out of each container. The roots will flow along with this and create the clogging issue which is already a concern. I check my pipes every couple days and move them away or loop them around with my handy plastic stick to keep it away from the main pipes that lead to the pump.

With the high flow you are going to have the issue of which ever buckets you pull from and how much you pull, the water level in those will be low, I am thinking you would need 4" pipes for the flow to work properly or you can try setting up the buckets in "steps" to control levels better and create more gravity feed gph.

I cant comment on running it on circulation alone, I looked at that method prior to building mine because of the same noise fear, but I figured out how to make it quiet. Running just waterfall in your res may work but you will make more noise than any of the air pumps with the amount of splashing you would need to get DO into it, I wouldn't run it warmer than 64F just to keep the DO up. You then also have the problem with DO becoming lower as it gets to the last ones in the circulation line? Better would be to have a water fall in each bucket as well like MEdGrower1 does on youtube
The slower flow works better, and the airstones keep the roots at bay. so far this run I have only had to root training only twice, seems to keep it self contain as they get bigger rather than having really long ones flowing into the other totes.

gr865 said:

@kingtitan, You are correct in you can get some cooling by running longer feed lines, but if you are pushing a large volume of air the heat is reduced a bit but will still effect the temp of the water.
Do you get pH fluctuation running air stones?

Click to expand...

With RO water I was going 5.5-6.9 by the time I check again (16-24hrs)

I ditched using RO and use my tap water with a hot tub/RV water filter to take out the chlorine and what ever else charcoal will get. I use the RO for top off and ill add tap if I need to adjust the PH up.

With tap I set at 5.8 and it will be 5.85 or 5.78 in 24 hours depending on what the plants are doing. some days it only changes by .1

My tap water is 210ppm (up to 250ppm during winter) and the PH is 8.3ish at this time of year. Yeah I got really hard water
Last water change I actually mixed in 20gallons of RO with my tap to bring it to 100ppm and didnt see much difference other than the wider PH swing (instead of .5/24h maybe went to .8/24h)

gr865 said:

@kingtitan, You are correct in you can get some cooling by running longer feed lines, but if you are pushing a large volume of air the heat is reduced a bit but will still effect the temp of the water.

Click to expand...

This is my first run of RDWC. I am using a 70L/min pump. with my first test with air pump and just using it the way it came RDWC was running at 74.3F max. With my bigger tube and 20ft run my temps max 66/67F. Now this isnt a controlled lab test or anything, I was just figuring things out. it could very well be that over 10ft of that line is on cold concrete before even getting to the room where the RDWC is. BUT compressing air creates heat, de-compressing cools it. So buying to big pump and blocking it off some will compress and heat, try to keep it so that the air doesn't have to deal with too much compression.

The sweet spot I found with my 12" Marina Elite stones was about 10.5L/min to each stone (roughly) I didn't see much variation by adding 20/30/40 or 50L/min to each. But I did notice when I opened up other valves which brought them down to under 9L/min

kingtitan said:

This is my first run of RDWC. I am using a 70L/min pump. with my first test with air pump and just using it the way it came RDWC was running at 74.3F max. With my bigger tube and 20ft run my temps max 66/67F. Now this isnt a controlled lab test or anything, I was just figuring things out. it could very well be that over 10ft of that line is on cold concrete before even getting to the room where the RDWC is. BUT compressing air creates heat, de-compressing cools it. So buying to big pump and blocking it off some will compress and heat, try to keep it so that the air doesn't have to deal with too much compression.

The sweet spot I found with my 12" Marina Elite stones was about 10.5L/min to each stone (roughly) I didn't see much variation by adding 20/30/40 or 50L/min to each. But I did notice when I opened up other valves which brought them down to under 9L/min

Click to expand...

As I stated in post #8 I do not run RDWC I run DTW so our systems are very different, I don't think we can compare A to A but if both systems work then all the better for us.
My D/O is just right using the passive method, but again I am working with coco in Smart Pots so they get plenty of O2 to the roots.
I have friends that run DWC in some contraption that can do 5 plants but it is not anything like yours, it sprays solution onto the roots and they grow into the base of the unit.
I like my coco, LOL.

GR

gr865 said:

As I stated in post #8 I do not run RDWC I run DTW so our systems are very different, I don't think we can compare A to A but if both systems work then all the better for us.
My D/O is just right using the passive method, but again I am working with coco in Smart Pots so they get plenty of O2 to the roots.
I have friends that run DWC in some contraption that can do 5 plants but it is not anything like yours, it sprays solution onto the roots and they grow into the base of the unit.
I like my coco, LOL.

GR

Click to expand...

Your friend is running Aeroponics

kingtitan said:

Your friend is running Aeroponics

Click to expand...

Well I went up to visit them a few weekends ago, his last grow was three LSD pheno's I had given him. One did not make it, don't know why they were perfect clones, and I smoke some of the other two. Tasted not so good, had no fragrance, and I did not feel the buz at all.
Yes I am sticking with my coco!
GR

I just posted this* to the YT video, but here is a picture of what I've been using. Going to replace it/them with bulk heads designed for trays as they have a built-in aerator

*I do not run RDWC (F & D instead), BUT... several grows back, I replaced my air pump/stones with a second lp pump in my rez. Had to put it on a timer to keep rez temps cool. I have been using basic bulkheads for feed and drain, but it occurred to me that bulkheads designed for F & D/E & F aerate the nutes as it enters each tote, which is the critical time.

PetFlora said:

I just posted this* to the YT video, but here is a picture of what I've been using. Going to replace it/them with bulk heads designed for trays as they have a built-in aerator

*I do not run RDWC (F & D instead), BUT... several grows back, I replaced my air pump/stones with a second lp pump in my rez. Had to put it on a timer to keep rez temps cool. I have been using basic bulkheads for feed and drain, but it occurred to me that bulkheads designed for F & D/E & F aerate the nutes as it enters each tote, which is the critical time.

Click to expand...

I think on the next cycle I will try pulling the air pump and air stones out and getting a second Mag 950 gal/h pump and set is as external with a venturi to pump into the rez + have the sprayers from the recirculating pump. is that what you mean?

EDIT: Actually the Danner Mag 7 comes with a venturi + air fractioner impeller, hmmm..exciting!

That should work, but why wait? Either get another bucket for your rez OR, siphon your rez into another vessel/s (cap the return) do the upgrade then refill

NOW, go back to RO. No way to know what quality minerals are beng used by your municipal water company. I have the same noisy ass air pump. Not only does it run hot, ti's crazy noisy, but more importantly, it pumps a lot of CO into your solution= raising pH

hth

PetFlora said:

That should work, but why wait? Either get another bucket for your rez OR, siphon your rez into another vessel/s (cap the return) do the upgrade then refill

NOW, go back to RO. No way to know what quality minerals are beng used by your municipal water company. I have the same noisy ass air pump. Not only does it run hot, ti's crazy noisy, but more importantly, it pumps a lot of CO into your solution= raising pH

hth

Click to expand...

What is this CO you say gets pumped into the solution?
Just curious!
GR

PetFlora said:

That should work, but why wait? Either get another bucket for your rez OR, siphon your rez into another vessel/s (cap the return) do the upgrade then refill

NOW, go back to RO. No way to know what quality minerals are beng used by your municipal water company. I have the same noisy ass air pump. Not only does it run hot, ti's crazy noisy, but more importantly, it pumps a lot of CO into your solution= raising pH

hth

Click to expand...

I have no worries with the tap here. My city has a very thorough and detailed analysis posted monthly. They have to if they want to keep their claim of being one of the best in NA.

certainly don't miss the RO at all. and my PH has been stable for weeks now. take a look at my logs

kingtitan said:

The key to running the bit pumps is big tubing on a long run. Check what I did with mine and the air from the pump actually can cool the water. People are running the pumps with the manifold on the 6 inch tube that comes with it. run 10-20ft of it.

the big air pumps are compressing which creates heat.
the short tube doesn't allow enough time to cool.
the manifold being close heats up (enough that you cant hold it very long) and then that heat also transfers to the small tubing

Click to expand...

Yes! The air pumps can cool the water (and certainly do) and I'll tell you how they cool my water. The air creates a vertical up/down dynamic of water current which makes the water circulate against the underside of the bin. That bin is not directly on the basement floor but close to it. That creates some heat transfer and couple that with the slight evaporative cooling effect of all those bubbles bursting above the waterline into the aeration zone above the water and under the lid. It more than outweighs the heat transferred from the blower. I know this to be fact because my water is always 6 degrees cooler than the air in the grow room in which the DWC bins reside. The bins are directly under the lamps.