DIY 'Under Current' RDWC style hydro; low cost, high output!

Discussion in 'DIY Farms' started by ttystikk, Mar 27, 2012.

  1. ttystikk

    ttystikk Well-Known Farmer

    I looked carefully at the UC and at several other designs- and then built my own. Things I liked about the UC- and incorporated; continuous recirculation of water, 'epi-center' concept, large water capacity, relatively small parts count, both in terms of total parts needed and number of different parts required; this simplifies keeping an inventory of spares. I did not like the lack of a 'tail' bucket, where water from several rows combines before being sent back to the epi-center; I find this to be the best place to add nutes and the like as it has a chance to mix and dilute both here and in the head bucket before it ever sees any roots. Also, a tail bucket tends to accumulate the crud or debris in the system, making it easy to spot and remove. Lastly, this is where I place my pump, with the filter still in place, with a line from it to the epi-center.

    For a 24 site system made of 5 gallon buckets, I've successfully used pumps as small as 250gph and as big as 650. Ironically, the smaller ones seem to work better.

    I used 1" bulkheads from n-g-w, as the ones from C.A.P. are made from poor molds and leak. I used 1" flexible tubing to connect everything, and it has the advantage of being much more flexible than PVC piping, and much easier to adjust, set up, take down, move or alter.

    Parts list and approximate costs for 24 site system:
    26 5 gallon buckets- free, I just asked around at local restaurants! Only take ones that had food in them, not nasty chemicals, or buy for about $6.00 each; get green or black- or buy some paint to block light...
    1 250gph submersible pump, $30.00 or so
    54 1" n-g-w bulkheads, I paid about $3.00 each in bulk
    50' 1" i.d. tubing, $1.65 a foot
    8 1" 90 elbows- shortens overall length of system to fit in light footprint, $2.50 ea.
    2 1" tees, plumbed just upstream of tailbucket, so rows drain more slowly into tailbucket than headbucket can fill them, this helps maintain water levels, $2.75 ea.
    100' airline tubing, $15.00
    1 Eco plus 7 200 litres/min air pump, $120.00 or so
    24 Eco plus medium airstones, $2.00 each in bulk
    Misc air fittings, $25.00 or so
    1 Float valve for top off, $20.00 swamp cooler part

    Ballpark cost is well under $500.00 for a 24 site system that will fit nicely in an 8x8 space. If you want it to cover more area, just buy more 1" tubing and airline tubing.

    Costs not listed include instrumentation of your choice- Blu Lab's Guardian comes highly recommended but it's pricey- and cooling; 1/2hp chiller will be more than adequate, and you could get by with 1/3hp if you choose to insulate the buckets with foil covered bubblewrap. I run a big chiller to cool not just my RDWC, but also my rooms, so I just dropped a 15' length of 3/8" i.d. copper tubing ($25.00) all coiled up to fit in the headbucket, ran some hoses to my cold water and return manifolds and bam!- cool running water, oxygenated, nicely mixed in each bucket due to the bubbling effect of the airstones. Operating capacity will be about 100 gallons of water.

    This design can of course be modified endlessly, to accomodate bigger buckets, more or fewer buckets, various center-to-center measurements, different shapes, and it's nowhere near as much of a c*ck-s*cker to tear down, move, adjust or alter. Word to the wise; if you decide to run more buckets, I wouldn't try running more than 8 sites in a row, and I would definitely use a smaller water pump (250gph) rather than the big one you'll be tempted to try, otherwise water levels will vary too much from one end of the row to the other.
    winta and lex0415 like this.
  2. Shane20

    Shane20 Active Farmer

    Nice work Ttystikk! You have any pics of your system empty or with girls? Thanks!
  3. ttystikk

    ttystikk Well-Known Farmer

    No pics yet, having trouble with getting them from my phone to the site.

    That said, I think the description above is pretty complete. If you're dying to know what it looks like, grab a few 1" bulkheads, install a pair in a 5 gallon bucket and cram some 1" tubing onto the bulkhead... it's really that simple.

    My point here was to show how easy it can be to build your own RDWC system, customized to your style, on the cheap with materials commonly available.

    24 sites for $500 is a pretty good deal, even the guy's used undercurrent was twice that.
  4. organicness

    organicness Active Farmer

    What kind of yields do you see from each bucket on average?
  5. ttystikk

    ttystikk Well-Known Farmer

    This is a big can of worms question. I have gotten as much as 8.5 oz dried cured from a single plant that came from this system, but I've been dialing things in and have still to get a really solid harvest, due to factors the system can't be blamed for.

    For one, I've been running nute strength way too low for the high levels of humidity, light and CO2 enrichment, so that screwed things up.

    For another, I have yet to get small enough plants to run all 24 sites at once; currently, I run 12 at a time in a checkerboard pattern.

    The buckets are really too close together in their current configuration, but one of these runs, I'll stick in a batch of 24 preadolescents and go all pedo with it, lol...

    I've been running salad grows the last few runs and of course that plays havoc with yields cuz everything you do is a compromise between conflicting needs of different strains. I've got a monoculture run coming up in a lil bit so we'll see how that affects things.

    Finally, I'm still working out how best to train their shape and time their progression through the veg stages so they arrive at the RDWC in best form to take off. SCRoG is a part of this, and I'm working out the details.
  6. ttystikk

    ttystikk Well-Known Farmer

    Here's what I can say about the RDWC's performance, however; it circulates water evenly and well and the 1" bulkheads flow plenty of water, provided you don't let roots grow into the tubing between buckets. I run airstones in each bucket, which encourages roots to drop down from the netpot into the water but still splash-waters the roots until they get there. For 24 sites, I run the Ecoplus Commercial Air 7, 200 liters per minute. Very effective. For 12 sites, an Ecoplus Air 5 is fine.

    The tailbucket is to me an essential component- and its main difference from an UnderCurrent- because this is where crud tends to accumulate from the rest of the system, greatly simplifying identification and removal. I run the recirculation pump in the tailbucket, with its filter trap in place. In addition, I can pour nutes and stuff into the tailbucket and it immediately dilutes before plants see it, helping to reduce nutrient lockout or root burn scenarios.

    Because the head bucket has four outlets and the tailbucket only has two, the water in the rows stays much more even from one end to the other. I've run pumps from as small as 250gph all the way up to 660gph and they all work fine- the smaller ones even seem to work out better. I put the cooling coil from my chiller in the headbucket as well, so chiller water circulates through it and the water swirling in the headbucket from the pump outlet passes over it constantly. My water temps range from a low of about 60 to 62 to a high of 66 to 68 at the end of the day cycle. I have a pet theory that this temp swing is actually beneficial to the plants... therefore I have no plans to fully insulate the buckets, though I am going to make some oversize lids out of the bubblewrap foil to cover them with. If this drops temps too much, I will just raise the temp setpoint of my chiller, this way I needn't worry about thermostatic switches on each RDWC.

    Roots are white, they don't seem to clog the system even when the bucket is crammed full of roots from a big specimen, again, as long as roots aren't allowed to grow into the connecting tubing. Due to the low temps I don't have to add anything for root zone health, although I add a bit of DM zone at res. changeout time, and bleach and flush between runs for preventative reasons. I am going to try Capulator's beneficials shortly, we'll see what that does for things!

    I'm considering changing the layout of my RDWC, and this will involve me buying more 1" tubing, more airline tubing... and nothing else. Cramming the tubing onto the bulkheads is not a huge chore, and the buckets can move around a bit for minor position adjustments easily since the tubing is flexible.

    I put a plank under the headbucket just to encourage waterflow. I may put two under it, one under each site and leave the tailbucket on the floor so water will flow out more fully at res. changeout time. This isn't critical, I'm just playing with things.

    Constructing the system was straightforward and simple. You'll definitely want one of those brass multistep bits that drills up to a 1 3/8" hole to fit the bulkhead in. The bulkheads all come with little rubber grommets and tighten into place with hand strength, no tools needed. A float valve like that in a swamp cooler will be plenty to keep the system topped off from a reservoir.

    I'm really happy with it- it works like a Porsche and costs like a used Chevy.
  7. organicness

    organicness Active Farmer

    Sounds sweet! Thanks for that writeup.
  8. tconch

    tconch Farmer

    with your 5 gal buckets what veg time & do your buckets completly fill with the roots,do they ball up or stay somewhat loose?also what are you using for lights ? thanks!
  9. ttystikk

    ttystikk Well-Known Farmer

    These are exactly the variables I've been working with- when I'm not battling other issues, of course lol.

    I vegged way too long, and yet no plant has ever choked on its rootball. Yes, the buckets will fill completely with roots much of the time, the rootball takes the shape of the bucket but it never clogs up the waterflow, just slows it down some. The roots like to grow down the tubes, best to keep them clear.

    I use mag. ballasts with 1000W HPS in Magnum xxxL 8" 'Ocho' hoods.

    I'm currently experimenting with smaller and smaller plants going in, though I don't veg in the same system I bloom in. The girls go into the veg zone for a few weeks, then get moved to flower. Both systems are RDWC. Part of the problem is I get taken by surprise by the speed of growth in veg and fall behind!
  10. swisscheese

    swisscheese Guest

    Any updates ttystikk on how your system is doing for you? Any pics yet?
  11. Badmf

    Badmf Farmer

    hell yeah post a pic soon me brains workin it ot.
  12. joehank

    joehank Active Farmer

    ^ What they said..
  13. ttystikk

    ttystikk Well-Known Farmer

    Wellll.... due to a whole damned pile of issues- none of which have anything to do with basic construction of the system- I decided to change my growth media for awhile. Got Homer buckets, drilled 25 holes in the bottom, filled with 50/50 coco/hydroton, put those buckets in the 5 gallon growin sites of the RDWC and I'm now doing a double layer grow; coco for growth and beneficials, and the RWDC underneath to catch the runoff and for a lil extra water for the girls. So far, so good...

    From a mechanical standpoint, this shows how flexible this system is, to be able to handle RDWC or substrate grows without any major reconfiguration.
  14. bigdaftones

    bigdaftones New Farmer

    Pictures would be awesome. :)
  15. ttystikk

    ttystikk Well-Known Farmer

    You raise an excellent point- and while I have some bits disassembled, this is a good time to do it. Give me a day or two, I'll get them up.
  16. SodaLicious

    SodaLicious Active Farmer

    Pictures are worth a thousand words!!!! I live the sounds of your system.
  17. SodaLicious

    SodaLicious Active Farmer


    Any luck with those pictures?
  18. ttystikk

    ttystikk Well-Known Farmer

    Fix one problem, find another. Internet down at the crib, should be back in a few days.
  19. SodaLicious

    SodaLicious Active Farmer


    I know what you mean!!! Fix one find another, sounds like my life.
  20. tilopa

    tilopa New Farmer

    Can you tell me some of the major issues you had with your original system. I'm trying to do the exact same thing and would like to avoid any pitfalls. Thanks.
    ttystikk likes this.