Monday, November 29, 2010

Deep Water Culture

While WindowFarms are a very efficient use of vertical space (the reason for their explosive popularity), they are not the only method of growing plants hydroponically.  There are actually a very large variety of different systems, each of which has it's own benefits and difficulties.  I will not pretend to be any expert on all hydroponic systems, but there are a few that interest me, and I have experience with.  My favorite of the alternatives to a vertical drip system is called Deep Water Culture, or DWC for short.  It is my favorite because it has the simplest construction, and has some of the best results.  Essentially it is just a reservoir; you have to mount net pots to hang into the solution, and aerate the water substantially.  The aeration is necessary for root growth, which uses oxygen, and the more the better (it also has the benefit of preventing anaerobic bacterial growth).  My system is a two gallon bucket (unfortunately plastic, but I am working with what I have laying around, I plan to transfer to ceramic or glass once I have the means).  I have two of the five outlets from my airpump running large airstones that I do my best to keep submerged under the root system (I plan to weigh them down with gravel at some point).  The top is a makeshift lid in which I have cut a to rest the four inch net pot in.   Currently I only have one plant (red cabbage) in my DWC, but it is doing fantastic, definitely the best of all of my plants.
Some pictures:
Approx. twelve inches across, for reference.
 Look at those roots!
 Be careful of the airstones, they like to float, 
it is ideal to keep them under the root system.
I am currently thinking about a way to potentially have the plants float on top of the solution, so that the reservoir does not need to be refilled as often.  And I continually attempt to integrate a DWC system into the reservoir of a vertical drip system.  I hope to actually do this with my Tower Two, which is assembled to support such a system, but I am waiting until after I move the system to attempt it.  But in any alternative system, replacing the reservoir with a larger volume, that has space for at least one net pot, and introducing an airstone into it is a way to utilize the most out of your system.

4 comments:

  1. I hate airstones they clog and float (the small ones also get brittle and shatter easily). after some experimenting with gluing the big airstones to the bottom and other various ideas that didn't work I started to use the t connectors for the air hose with a few washers on it to make sure it stays at the bottom of the bucket. plus the t connectors are easy to clean with a safety pin when they get clogged. I don't like that the washers corrode a little but I don't like having pythium attack my roots more so it's a trade off I except. just some thing to think about.

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  2. Yea they aren't perfect, but I think they are the best I have for the moment. The problem with just putting in a hose is that the air bubbles aren't broken up enough and don't dissolve into the water as readily. I was thinking of possible putting a layer of sand on the bottom, burying a hose under that, making a more natural diffuser, but haven't had the time to fiddle with my DWC. I did like the washer idea, and scavenged a few hex-nuts to weigh down my airstones though, works great! Thanks for the comment!

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  3. oh I was thinking about it and a little paint on the metal parts should keep them from corroding.

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  4. Yea, or possibly some paraffin/ beeswax if a little skeptical about the unknown compounds in the paint. Also, I have been designing some other potential diffusers using remnants from glass bottles on the vertical farms, though I probably won't put it into action until I have a more 'organic' reservoir. i will try and scan in my drawings an post them in the near future.

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