RDWC/Under Current System newbie questions!

FRANMACHINE

FRANMACHINE

Well-Known Member
Hey guys! I'm currently designing the next system I will be using which is the RDWC/Under current system. However, there are questions that I can't seem to answer. Hope you guys can help me out!

I will have the exact same setup as this thumbnail below. 8x 5 gal Buckets and 1x 5 gal control bucket/reservoir.
Under Current System.jpg

1. How do you place nutrients in this system? -- Do I just place it in it's reservoir? (I have 9 buckets of 5 gal which means ill place the total amount of nutrients per L for the 9 buckets directly into my reservoir?

2. How strong of a water pump/air pump should I have in a system like this? Is there a required amt of gallon per minute for this system? Like wise with the air pump?

3. How large of a net pot should you have for this system? Does the size of the net pot matter even though my buckets are 5 gallons? What is the minimum and maximum size?

4. For the pipe line connected to all the buckets, is it wrong to have a 2' pipe line? Is there a difference if I use a 1/2' pipe line and a 2' pipe line? Can the pipe line be too big?

5. Finally, should the net pots be submerged into the water or should it be above the water? How high or how deep should it be?

Help would be greatly appreciated!! Will make a grow journal once my equipment has been gathered.
 
M

Medicationist

Member
1. Yeah just put them in the controlling reservoir. It shouldn't take too long to equalize in the other buckets.
2. Your water pump needs to be under what your return pipes/tubing is rated at. For 3" pipe you can have something like 2500gal pump if I remember right. If you are pumping too much water your pots will overflow. Also, if your feed lines are too big, pressure wont be high enough to reach the buckets farthest from the controller. With air pumps you really should only get what you need. If you have enough water dripping and agitating the surface of the water you can go without an air pump altogether. Make your own waterfall fittings and you wont have an issue. :)
3. I haven't noticed that much of a difference. I have one 8" square pot that fills about 2/3rds of a 27 gal tote, and 2 plants in 3 5/8th inch pots in a 37 gal tote that fills up the whole bucket. Keep in mind the smaller the net pot the more chance it will have to topple over. Build a scrog or trellis that attaches to the lid to prevent this.
4. I don't think the length of pipes really matter too much as long as it has pressure to push all the water through the system. I have some totes connected with a foot long pipe and others with 2' lengths.
5. This is a debated question. Some say an inch below the pot. I use a drip feed for the first couple weeks and have the water an inch below. But then I crank that water level up as high as I can. Really the only difference I can see is if you want to build the fuzzy roots to grow around the net pot.
 
blackforest

blackforest

Well-Known Member
I pretty much built this exact same system and am currently running it. My system is 6 buckets with an epicenter (rez).
I put my nutes into the epicenter directly, since I use GH, I put in the micro first, let it mix, then the bloom, cal mag and hydroguard
I have a 793 gph water pump which recirculates all the water in about 4 minutes, seems adequate for this many buckets. My air pump is 951gph, which does a decent job, I will upgrade this my next run.
Mine are in 6" net pots, I see they have 8" and 10" at the grow store, 6" works just fine for me. They are designed to fit onto a 5 gal bucket so they snap into place.
My system is connected with 2" pvc which is great and unrestrictive. DO NOT go smaller imo, roots will clog up the system and it won't flow. My next system will have 3" or 4" piping
My net pots are 1/2" above the water line. Float valve in the epicenter keeps the water at a constant level.

I saw a friend's undercurrent system and built my own. So far so good as my thread states, good luck!
https://www.rollitup.org/t/rdwc-build-so-far-so-good.852489/page-2#post-11203766
 
FRANMACHINE

FRANMACHINE

Well-Known Member
TWS said:
we'll see ya in the Hempy thread.;)
Click to expand...
haha definitely

Medicationist said:
1. Yeah just put them in the controlling reservoir. It shouldn't take too long to equalize in the other buckets.
2. Your water pump needs to be under what your return pipes/tubing is rated at. For 3" pipe you can have something like 2500gal pump if I remember right. If you are pumping too much water your pots will overflow. Also, if your feed lines are too big, pressure wont be high enough to reach the buckets farthest from the controller. With air pumps you really should only get what you need. If you have enough water dripping and agitating the surface of the water you can go without an air pump altogether. Make your own waterfall fittings and you wont have an issue. :)
3. I haven't noticed that much of a difference. I have one 8" square pot that fills about 2/3rds of a 27 gal tote, and 2 plants in 3 5/8th inch pots in a 37 gal tote that fills up the whole bucket. Keep in mind the smaller the net pot the more chance it will have to topple over. Build a scrog or trellis that attaches to the lid to prevent this.
4. I don't think the length of pipes really matter too much as long as it has pressure to push all the water through the system. I have some totes connected with a foot long pipe and others with 2' lengths.
5. This is a debated question. Some say an inch below the pot. I use a drip feed for the first couple weeks and have the water an inch below. But then I crank that water level up as high as I can. Really the only difference I can see is if you want to build the fuzzy roots to grow around the net pot.
Click to expand...
Thanks for your insights!! Will keep these in mind! As for the water level, i heard it's better to be below the net pots cause it's the splash from the bubbles that hits the net pots which is important.

blackforest said:
I pretty much built this exact same system and am currently running it. My system is 6 buckets with an epicenter (rez).
I put my nutes into the epicenter directly, since I use GH, I put in the micro first, let it mix, then the bloom, cal mag and hydroguard
I have a 793 gph water pump which recirculates all the water in about 4 minutes, seems adequate for this many buckets. My air pump is 951gph, which does a decent job, I will upgrade this my next run.
Mine are in 6" net pots, I see they have 8" and 10" at the grow store, 6" works just fine for me. They are designed to fit onto a 5 gal bucket so they snap into place.
My system is connected with 2" pvc which is great and unrestrictive. DO NOT go smaller imo, roots will clog up the system and it won't flow. My next system will have 3" or 4" piping
My net pots are 1/2" above the water line. Float valve in the epicenter keeps the water at a constant level.

I saw a friend's undercurrent system and built my own. So far so good as my thread states, good luck!
https://www.rollitup.org/t/rdwc-build-so-far-so-good.852489/page-2#post-11203766
Click to expand...
Appreciate the info! Gonna use a 6-inch net pot as well! I've seen RDWC systems for sale with 1/2' rubber piping though. Why is this?
 
blackforest

blackforest

Well-Known Member
FRANMACHINE said:
haha definitely


Thanks for your insights!! Will keep these in mind! As for the water level, i heard it's better to be below the net pots cause it's the splash from the bubbles that hits the net pots which is important.


Appreciate the info! Gonna use a 6-inch net pot as well! I've seen RDWC systems for sale with 1/2' rubber piping though. Why is this?
Click to expand...
Well, technically it would be a rdwc because it's recirculating. The system I built and what you are referencing is an undercurrent rdwc system. For an undercurrent to be effective, you need larger diameter pvc to ensure a good flow since the system is basically gravity fed. I've seen the system with the smaller lines before, and it looks good in theory. I just can't vouch for it personally but have thought about building one for veg growth just so I don't have to change out each bucket once a week. I just don't think the smaller diameter lines are an actual 'undercurrent' system. I've also been told that if you have small diameter lines you can potentially suck a lot of water out of the last bucket and it can't fill up fast enough to keep up with the water pump. With these 2" lines, I can pour in a 5 gal bucket into the epicenter in like 2 seconds and it easily disperses into the system instantly. This ensures all buckets are always the same level all the time.
 
M

Medicationist

Member
Smaller tubes have more chance of clogging from roots, slime or nute build up. If water cant recirculate a tote or bucket will overflow which can cause water damage or burn out your pump rather quickly. The only downfall imo with bigger pipes is they are a little harder to work with. But that won't stop me from using 3" again on the new system I'm building next month.

The whole debate about water level varies greatly between growers and relies a lot on the equipment you have getting enough air to the roots. I have one system that can take the water all the way to the top of the net pots. To the point it's touching the main stem. And it is doing way way better than my other system that can't get the water closer than 2" away. Also, the more water you put in there the less pH and nute fluctuations you will have. I say as long as your system supports it raise that water up.
 
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