To Raft or Not To Raft, that is the question

[TCLynx]

So, I've got this nice long DWC bed and I'm contemplating ways to use it.  I'd like to get a topic going here where people can show off their innovative methods of supporting plants for DWC or just simply show and tell how they went about constructing their rafts or support boards and what they think of it.

What materials did you use?
What paint or sealer did you use?
How did you cut the holes?
How did you support the rafts/boards while you pained and let them dry?
What size did you go with and would you change it nest time?

What did you like about what you did and what would you like to do different?

I rather like the idea of supporting the plants some how above the water instead of having the raft on the surface for any situation where the bio-filter surface area is not needed because this may greatly reduce the amount of supplemental aeration that would be needed for the raft bed.  I've found that the few times I have tried small rafts, the plant pots setting down into the water kept things too wet for many plants unless there was a huge amount of supplemental aeration under the raft.

For letting the plants get moisture before their roots hit the water, I like to use wicks and I'll have to get some photos of those up into this discussion once I go find them. Here is an album with photos of the wicks I use http://aquaponicscommunity.com/photo/albums/cups-net-pots-wicks

Please jump in and share.
:) :) :) :)

[Darryl Hinson]

Hey,TC...can you recommend a book or two on raft systems.
I have a 4 ...soon to be 8 barrel gravel bed set up and I think I'd lke to put some herbs in some plastic pipe....I've seen pictures but dont know the perameters......
Where does a guy learn about this stuff.....there are no classes in my area....non at the local college, etc....
Darryl :)

[Raychel A Watkins]

Aloha
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

[Harold Sukhbir]

Hi Raychel. I was wondering if you used any additional aeration in you troughs as was suggested to me by a friend as necessary in preventing root rot?

Raychel A Watkins said:

Aloha
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

[David Hart]

Raychel, thanks for sharing your experiences with the rafts :)

You wrote... I was a cheapo and put 1 and 1/2 inch styrofoam on the top. Would not do that again.

Would you please tells us what happened / why you won't do that again ?
Also were the sheets 1 1/2 thick, or were you using 2 different sizes...some 1/2 inch thick....some 1 inch thick ?

"Thanks Raychel"...I think this will be an important point to clarify, for anyone trying to do rafts

[TCLynx]

Darryl,
Sorry, I don't know a good book on the subject of raft systems. Kinda why I started this thread actually. Most of my education on Aquaponics came from the BYAP Forum and there I usually send new people to read the Basic Info and Useful Info sections and then tell them to pick a couple of the big long member system threads and read them all the way through (keep a note of what page you leave off since some of those threads are too long to get through in one sitting.) However, BYAP is mostly media based growers.

Here there is a wider array of methods being discussed it seems and a heavier emphasis on the fish types commonly used in the USA.

Anyway, Thanks all for sharing some about your rafts. I'd love to get some of the even more outlandish and creative ideas here on the floor so see what people have thought of them.

[Raychel A Watkins]

Aloha
So far I do not have a system with a raft and a gravel bed. It is something I want to try. I do not put areation in my troughs only in the fish tank. My do stays between 3 to 6 ppm depending on the system. I have had rafts with filters and rafts without filters. I think mostly the filters are a waste of material. One should try a filter and see what happens. As I said my roots hand down in the water and do not rot or get clogged. My barrel system is rafts and the lettuce matures before the roots leave the pot. I am using 3 in net pots. The styrofoam was 1 1/2 in thick and when I put big pots in it (3 gall with my taro) it tended to break. If the lettuce got to heavy it would break also. I now am using the coolers I get from work. The have a very thick hard 2 to 2 1/2 inch thick top and sides and they are free and clean just used for shipping and cold. These do not break even with a 3 gallon pot but they are small about 2ft by 2 ft or less. I can say I love both rafts and gravel eequal because of the different plants in each. I will try to get some more pictures up after I get home.
Mahalo for such good discussions

[TCLynx]

Yea, the cooler ideas is a good one. If anyone has a neighbor that gets Omaha Steak delivered or anything like that, they might have extra coolers they could give you. They won't be big but they might be useful.

I have a long narrow foam cooler that I scrounged years ago that I cut down a bit and had been using lined with plastic to grow lettuce in Hydroponics way back when. I still have it and I think I might just float it in the DWC bed and perhaps punch some holes in the bottom (pull some wicks through if it seems to be needed) and perhaps just put media directly in the cooler and use it as the plant container.

I've also just put a bit of capillary matting onto a bit of 3/4" foam (edge hanging off into the water) and set a couple seed trays on the matting. Will see how that works for starting seedlings.

All sorts of things to try :)

[Harold Sukhbir]

Great idea Kobus,suspending, to increase aeration directly to the roots and water.
Kobus Jooste said:

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.

[Brian Maclean]

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.. 

[TCLynx]

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.

Aquaponics System parts

[Rob Torcellini]

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!  

[Brian Maclean]

Thanks Alot.. this info helps