Have a quick question for those who can help I have a six bucket 5 gal rdwc with a simlar size control I used 2inch pvc for the water supply and 1/2 pvc for the return my water pump is 397gph and I have approximately 25 gal of water in the system. I can barely see the water moving is that how it should be?? This is my first grow and I really dont know what to expect, water level is the same in all the buckets and I dont have an issue with overflowing the buckets just need to know if my return was to small or am I just worried for no reason????
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return line question
- Thread starter thebbqman
- Start date
noob1988
Member
I do not have any experience with the above situation but have you added nutes yet? Can you see how fast they move threw your system? Or is a few drops of food coloring safe to give you a visual idea? But in the end, if none of your buckets are overflowing and staying the same height.. and your pump is pump close to the GPH you stated, then the water MUST be recirculating. with that said, why did you put 1/2 return line? most setups ive seen people use 2 in. I had to order mine online bc I could not find any near where I lived.
I used 2inch for the main water supply and half for the return linen and yes I did add nutes and they did move to all the buckets, I guess I was expecting a stronger flow in each bucket but, since this is my first grow I dont know is that right or should it flow harder in the buckets????
Miraculous Meds
Well-known member
Check out snypes guide to rdwc. U got ur sizes backwards. Usually small pipe to feed and large pipe for the return so they don't clog with roots. Plus I think u need a bigger pump, probably 1000gph or something the like. If I were to build one of these id actually copy heath robinson's, I think he posted in his tree thread.
Miraculous Meds
Well-known member
Light leaks, high water temps, faster water flow. I think about 1ml bleach in that much water every 4 days would be an option too. Id recommend looking up heaths specs on his water gph.
Miraculous Meds
Well-known member
2" pvc for the water supply, what do u mean hear? Do u have a 2" line connected to the 396gph pump?
Miraculous Meds
Well-known member
Here u go bud this is the shit. Check out the thread titled heaths latest tree grow on this site. u can read the whole thing if u want but I found he describes his system on page 8, and answers his water flow rate on post 108 or so. He says 500 liters per site min but he likes 1000 liters per site, so that's 125 to 250gph per site. So if u went with a 1000gph u would be on the top end and probably have less probs with root rot. Any way that thread is epic and if I were to do rdwc again that's how I would do it. In fact I did his flooded tubes but I added to much bleach and fried my roots. Took off the whole outer part of them, and still broke a gpw.
Miraculous Meds
Well-known member
I don't get it how do u feed, with a line going thru the top of the bucket?
Miraculous Meds
Well-known member
How does it return, Do the 2" lines go thru the wall to a control res?
Don't get hung up on any one person's system. You need to first understand the fundamentals and then either buy an UnderCurrent system or custom design your own. As someone mentioned you got the flows inverted, the drainage should have a much bigger return (the bigger the better, 3" or 4"), and you need a serious pump and DON"T use a submersible. Get a quality inline. Yeah they're spendy but required.
Miraculous Meds
Well-known member
Did u look at his pic. I cant figure out how this is plumbed?
I think that you are confused about some terms. From your pictures, it appears that the 1/2" line goes to the pump outlet port in the control bucket. That makes it the pressure, or supply, line.
The 1/2" supply line is teed into the 2" pvc at the point furthest from the stud wall. The flow is then divided both ways, and the 2" pvc connects each bucket, through the wall, and back to the control bucket. This is the return line.
The pump isn't capable of giving you any serious water movement. 397gph is 6.6 gallons per minute. This flow is split into two by the tee, so each side is getting 3.3 gallons per minute at peak pump efficiency. The flow velocity through the 2" pvc is about 8" per second, but when the pipe opens up into the next bucket it will slow down to the point that a complete exchange of water will take 72 seconds. Pretty slow.
I've never used one of these systems, but my understanding of the UnderCurrent theory is to move the water pretty quickly and help with oxygenation as well as all of the benefits that conventional RDWC gives.
The 1/2" supply line is teed into the 2" pvc at the point furthest from the stud wall. The flow is then divided both ways, and the 2" pvc connects each bucket, through the wall, and back to the control bucket. This is the return line.
The pump isn't capable of giving you any serious water movement. 397gph is 6.6 gallons per minute. This flow is split into two by the tee, so each side is getting 3.3 gallons per minute at peak pump efficiency. The flow velocity through the 2" pvc is about 8" per second, but when the pipe opens up into the next bucket it will slow down to the point that a complete exchange of water will take 72 seconds. Pretty slow.
I've never used one of these systems, but my understanding of the UnderCurrent theory is to move the water pretty quickly and help with oxygenation as well as all of the benefits that conventional RDWC gives.
Miraculous Meds
Well-known member
Ok now I see ur control res pic. So ur pump feeds the control res which flows thru the 2" lines into the plant buckets, back to the pump. Ive never seen it set up that way That is no where near enough pump for this system. I would set it up with a 1000gph top feeding each bucket, and use the 2" lines to return to the control res. If u do it this way then u can ditch that air pump which does nothing for DO, compared to the fast flow top feed rdwc style im talking about. that's whats causing ur root rot, u don't have enough water movement, creating DO.
You are right doesn't make sense, sorry bbq.
However you design it, you should have rapid water exchange in each container and some type of aeration. Aeration (dissolved oxygen DO) can come through air stones or by agitation. Streams and rivers that drop and/or have rock/obsticales along with the speed are determing factors when deriving DO in such waterways.
If you truly want to know proper sizing. flows etc. there are a few concepts you need to learn about. Here's what you will need to research:
Streeter-Phelps equation - what it means and how to use it
DO=DOs - [(kd*Lo/kr-kd)(e^(-kd*t) - e^(-kr*t)) + Do*e^(-kr*t)]
There's a lot behind it but by understanding this equation you will have taken in a lot more info to get to that point.
Streeter-Phelps equation - what it means and how to use it
DO=DOs - [(kd*Lo/kr-kd)(e^(-kd*t) - e^(-kr*t)) + Do*e^(-kr*t)]
There's a lot behind it but by understanding this equation you will have taken in a lot more info to get to that point.
