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What is the optimal design width for Deep Water Raft Construction? My concerns are ability to reach the plants; cost of construction; water issues.

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I have the net pots touching the water by about 1/4" .  I wouldn't worry about having a "pitched bottom, seems like the water current moves everything along pretty well.

Hi Juim,

How many sq ft are your troughs?

I find that if you have access to both sides a 4 ft wide bed is a good distance if you need to reach the center but with me (6ft tall) I can go to 5 ft wide and still reach the center. this is for a raised bed top being about 20 inches off the ground to lean against, also the shorter person will have issues reaching the center over 4ft wide.  and if you only have one side access you may only get a 3 ft bed. 

Keep in mind that most large hydroponic systems are 30 feet by 100 ft. they don't bother getting to  the center much. the crop moves from one end the the other. this way there is less risk to the working from leaning over a pool of water, tools falling causing repair needs to the liner for the tools being dropped.  and lest walkways equals more product. 

I would suggest putting together a simple frame. to represent the top out line of a bed. using 1x1, 2x2, or 2x4's to screw it together. you could even used scraps. the idea is to have a picture frame looking thing. set this on blocks or screw a few legs (nothing fancy) just something to hold it up at the level of where you would want the top of the bed to me. try different widths, lengths and layouts. this gives a great tool to walk around feel how the layout works and even see if there will be any issues. I would suggest leave them set up for a day or so to allow you to walk in and out a few times and see how you like the lay out. Don't forget about the pluming. sometimes the better bed layout make to pluming a mess. 

i hope this give you a few ideas how to figure out what grow bed widths work best for you. and that is what is great about Aquaponics there is now right way there is only what works best for your system. 

Great idea about a mock layout. Could be as simple as corner stakes and string lines at the proposed height. Since I'm going with masonry on my raft beds and fish tanks I can't afford expensive redos. 

yes i tried to stakes and string. It dose work but longer to setup and move when trying different layouts.   you can always use pvc and just not glue together. 

Also i fond that having a 3 inch high clearance under the bottom bed is great for your toes. you can lean farther when your feet are under the bed then next to it.

Mark Hall said:

Great idea about a mock layout. Could be as simple as corner stakes and string lines at the proposed height. Since I'm going with masonry on my raft beds and fish tanks I can't afford expensive redos. 

@ Ned: 

My test "suspended rafts" are 2' x 4' and work well.

@ Mark: 

The air gap is around 1" as the "raft" is 1/2" thick and the net pots are just into the water column.  Water wicks up into the cinders well enough to germinate seeds.  When the seeds are tiny, I pour a handful of fill sand into the cinders before adding seeds and cover them with a little more sand, works great...

Figuring out how things fit together is the key to being efficient.

When I bought a new house years ago I realized the patio was  not going to work.  I built a red brick patio over the ridiculously small 8' x 8' existing patio. After the 10' x 12' RB patio was in, I found that I still walked in the grass to get around the table .  Not big enough...  I then put the garden hose across the yard next to the patio and every time I stepped over the hose I kicked it out a little further.  I ended up at 16' from the house and it's now 36' square with additional details along the house for walks etc.  The patio worked out to be about 50' long in total along the house.  That is still the best patio I've ever had.  IMHO 16' is minimum distance width from a house.  

I am a big fan of mock ups.  I will use PVC pipe sections to figure out my planned DWC grow beds before I build them.  I'm planning to build along the outside of the lot about 3' wide all along the back and side fence/wall to create more than 200 square feet of GB.  It will all run as one tank with just one pipe to the filter and only a folded 90 degree angle in the pond liner.  That water pipe will run inside the DWC tank.  In the winter, during the warm daylight hours; I'll run the water up through 1/2" black irrigation pipe to solar heat the water keeping the roots and fish happier  The radial filters will be at the head of the deep water channel and the water will just flow back into the in-ground fish pond over a spill way.  I'm planning to grow things in media pots (cinders) and in the previously mentioned fixed height suspended rafts.  There will be sections for duck weed production, fry grow out and I'm planning to throw some crayfish in there to see how they do too.  I was at Dave Story's home in Tucson a few weeks back (thanks Dave) and he gave me a hand full of AP grown Merlot grapes that were just awesome!  That made me think outside my paradigm and I now realize I need to expand my 50 Sq. feet of GB to something really productive.  Grapes grow well here in the desert as so do most fruit trees and bushes.  This design will allow for lots of grow space without reducing my yard to a useless food production facility while providing most of the fruits and veggies I use.   I'm also planning to add in a section of wicking beds (side yard) that are plumbed directly into the system for tuber type plants, fruit trees, bushes, and in-ground crops like carrots and scallions that do better in dirt but will still benefit from the sweet AP water. 

Question(s):  I'm thinking I would like to use a redwood frame around the top of the big trench.  I'm planning to use a double layer of wood with the pond liner trapped in between the tightly screwed layers of the frame.  The redwood would basically just sit on top of the block wall with bracing to keep the boards parallel and separated the correct distance (3').  Has anyone tried this method?  Does anyone see a long or short term problem with this method?  Also, what height do you prefer the raft surface above the floor?  Does anyone see a problem with channels deeper than the normal 12"-18"; water is cheaper than fill dirt and easier to shovel...

thanks,

Jim

well jim the more water the more root zone. however not every plant  need such root zone. lettuce you can get away with 6 inches where a citrice that is green year around need at least a foot. but having more allows for the water to freely move under the plants but beware that this may cause stagnant arias. maybe adding in multiple inlets direct the water up into the roots or baffles that force the water up would avoid this. but maybe hard to add or change once plants are growing. Lettuce and short lived plants would nit have this issue only plants that live a year or more.

Jim,

Hey, I've been growing scallions in my rafts really easily,  I have attached a 6' high screen all the way around the perimeter to keep the tops from interferring with the rest of my rafts.  Grow our real quick.

I, too, am a fan of mock ups but I do them on paper...at 6'4" I'm a little sensitive to counter heights, door heights...you get it.  Vertically challenged!



Jim Troyer said:

@ Ned: 

My test "suspended rafts" are 2' x 4' and work well.

@ Mark: 

The air gap is around 1" as the "raft" is 1/2" thick and the net pots are just into the water column.  Water wicks up into the cinders well enough to germinate seeds.  When the seeds are tiny, I pour a handful of fill sand into the cinders before adding seeds and cover them with a little more sand, works great...

Figuring out how things fit together is the key to being efficient.

When I bought a new house years ago I realized the patio was  not going to work.  I built a red brick patio over the ridiculously small 8' x 8' existing patio. After the 10' x 12' RB patio was in, I found that I still walked in the grass to get around the table .  Not big enough...  I then put the garden hose across the yard next to the patio and every time I stepped over the hose I kicked it out a little further.  I ended up at 16' from the house and it's now 36' square with additional details along the house for walks etc.  The patio worked out to be about 50' long in total along the house.  That is still the best patio I've ever had.  IMHO 16' is minimum distance width from a house.  

I am a big fan of mock ups.  I will use PVC pipe sections to figure out my planned DWC grow beds before I build them.  I'm planning to build along the outside of the lot about 3' wide all along the back and side fence/wall to create more than 200 square feet of GB.  It will all run as one tank with just one pipe to the filter and only a folded 90 degree angle in the pond liner.  That water pipe will run inside the DWC tank.  In the winter, during the warm daylight hours; I'll run the water up through 1/2" black irrigation pipe to solar heat the water keeping the roots and fish happier  The radial filters will be at the head of the deep water channel and the water will just flow back into the in-ground fish pond over a spill way.  I'm planning to grow things in media pots (cinders) and in the previously mentioned fixed height suspended rafts.  There will be sections for duck weed production, fry grow out and I'm planning to throw some crayfish in there to see how they do too.  I was at Dave Story's home in Tucson a few weeks back (thanks Dave) and he gave me a hand full of AP grown Merlot grapes that were just awesome!  That made me think outside my paradigm and I now realize I need to expand my 50 Sq. feet of GB to something really productive.  Grapes grow well here in the desert as so do most fruit trees and bushes.  This design will allow for lots of grow space without reducing my yard to a useless food production facility while providing most of the fruits and veggies I use.   I'm also planning to add in a section of wicking beds (side yard) that are plumbed directly into the system for tuber type plants, fruit trees, bushes, and in-ground crops like carrots and scallions that do better in dirt but will still benefit from the sweet AP water. 

Question(s):  I'm thinking I would like to use a redwood frame around the top of the big trench.  I'm planning to use a double layer of wood with the pond liner trapped in between the tightly screwed layers of the frame.  The redwood would basically just sit on top of the block wall with bracing to keep the boards parallel and separated the correct distance (3').  Has anyone tried this method?  Does anyone see a long or short term problem with this method?  Also, what height do you prefer the raft surface above the floor?  Does anyone see a problem with channels deeper than the normal 12"-18"; water is cheaper than fill dirt and easier to shovel...

thanks,

Jim

Hi Ned,

nor sure what 'a large scale' would be. I use a different version of this: I built something like rails out of 25mm PVC pipe, with the Thing on top being a 40mm pipe. My beds are 4m x 1.25m. I slide the insulation boards along, so the biggest ones are closest to where the water comes in in order to receive most nutrients. See images below.

Ned Berndt said:

Has someone used the "suspended shelf" design on a large scale?

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