I started out with troughs and rafts because I didn't know there was any other way. I went to the Friendles class in Oct 2009.
I came home and built 2 rafts on the ground immediately and hooked them up to 3 250 gal tanks with young tilapia. I built the trough much like Chris Smith's. I used 1/2in plywood for the sides and a 2x4 along the top. I bought the black pool liner at Home depot and made a liner. I used treated wood. I put through the bulkhead fittings for water to go in and out. I put a small fountain pump into trough 2 and pumped the water back to the fish. I set up a sweetwater blower and put air stones in the tanks. One trough was 4 ft by 48 ft and one was 4 ft by 25 foot. I was a cheapo and put 1 and 1/2 inch styrofoam on the top. Would not do that again. I bored the holes with a hole saw. I use my own coconut fiber for the material in the pot. I grew lettuce, Ung choy, taro, celery, tomatoes, and some other plants like water cress. It was and still is wonderful. But it will kill your back. I have since pu up 4 more troughs but they are waste high and work wonderful. Never do it on the ground. I have since started using gravel beds also and love them for I can now grow cucumbers which I am adddicted to. When I get home from work tomorrow I will put up some pictures of my troughs and gravel beds. On the photo page you can see that I have two tanks growing roses one is a raft and one is gravel. I love both ways.
Mahalo for starting this discussion I hope many others will join in. We need to see the different ways and have some detail of how to do things. My plants are down in the water and they do not collect things on their roots for the most part
I have a small experimental "raft that is a standard plastic bin, around 11 inches deep, with the polystyrene raft suspended slightly above the water to allow a water - air interface. 3 inch pots are 50% in the water 50% out, and contain perlite or gravel to hold the plant into place. I do not use wicks. All seem fine, but the only hasstle thus far has been using a slightly thin polystyrene that bigger plants such as kale can warp over time. Otherwise I like what I have done and have been getting good results. One thing I may consider is to do is to add a air line in, not for permanent aeration but to switch a small pump on periodically to flush settled solids out.
TCLynx, are you still using this method or have you improved this great idea. I'm in the process of making raft boards over a 3ftx6ft "fill & drain bed". Are those yogart containers? I'm also trying to figure out the best size of netty pots to start with. It would be nice see some info for the right size pot to use for each plant, not just for seedlings..
Yes those are yogurt cups with holes poked in the bottom.
I really have not done a DWC raft type bed effectively yet. I keep putting pond plants in those beds and never seem to get around to making rafts and at the old house the well water kept the pH too high so the plants all seemed to do better in media rather than raft or nft anyway.
Now that I'm on the new farm and am collecting rain water so the pH can settle lower, perhaps I'll get a functioning raft set up going but I have not done it yet.
For most commercial production of salad and herbs it seems the 2" net or slit pots seem to be the way to go but you need to make the holes for them like 1 7/8" I think is what I've heard. I wouldn't know what the "best" size net pots are for anything. I grow most things in media beds and towers currently. I wouldn't be transplanting seedlings from one size to another, it's best to place the seedlings directly into the size net pot they will grow out in I think.
Lots of aeration for the "raft" beds also seems to be a key to thriving plants in DWC. The pond plants don't seem to require that so much.
I've set up my system with the 2" pots and have only grown lettuce in them so far. I used some expanded shale for the media: I found that screening out the larger stones so everything is 1/2" or smaller works really well. When I'm done with the plant, I just break off the roots, shake off the shale, and can reuse it right away to replant. 100% recyclable!
I was worried about aerating my DWC, but (so far) have found it not to be necessary. I'm not sure why but I have 3 theories - have no idea if they are accurate or not!:
1) Because I'm draining my media beds right into the raft bed. The volume ratio of my media to raft is 1:2 (media bed is 1/2 the size of the raft). I think there's enough air getting added to the water during the flood/drain process. Some day I may actually invest in a DO sensor so I can see what it is!
2) The water coming out of the media bed has no solids so there is nothing getting stuck on to the roots.
3) My water temp up here in the great north is cold, even in a greenhouse. Yesterday it was 73, which is a bit on the warm side.
I also keep 2 small koi in the raft to control the mosquitoes. I have to keep them small or they start nipping at the lettuce and duckweed.
Also, I don't transplant the seedlings once they are in the pot. I tried it and it damages the roots and slows them down a bit. I did a side-by-side comparison between planting directly in the net pot vs. transplanting and I would loose about a week of growth. I just plant a bunch of extra pots for each of my rafts and discard the ones that don't germinate. I've had no problems with moving full pots from one raft to another, but it's rare I need to move them around.
Here's the details on my setup: http://www.youtube.com/playlist?list=PL2402DC95ADAFA04E&feature...
So far, I'm happy with the raft for doing the quick crops like lettuce....and still believe that the media is best for the vine-type plants. Just my 2-cents worth!
Thanks Alot.. this info helps