Rafts for DWC

[Michelle Silva]

As suggested, I'm adding blog post below to "forum"..still need to learn how best to use this site.Thks.

 

Can anyone advise what the difference is between using Dow blue boards and the white 2" styrofoam at Home Depot. Do the dow blue boards need to be painted? I don't know if I would ever try to be "Certified Organic" but I would want to do what is safest.. Does it make a difference? Thanks.

[TCLynx]

Hum, those look suspiciously like the pound together floor pads. Just because there is a picture of it there, doesn't mean it is a product they sell, it might just be a picture of an instillation where much of the other stuff in the picture is stuff they sell.

As to using wood suspended over the raft tanks. Well yes it would be a trade off. The water would have some better aeration because the foam isn't sitting directly on the surface but you would loose that surface area as part of the bio-filter. So it would all depend on the design of the system if that would work. If there is a separate bio filter on the system, then loosing the underside of the raft as surface area might not be that big a deal but if it is a bare minimum system like the friendlies mini system, then you need that surface area since there is no additional bio-filter to depend on. But by suspending the plant support surface you avoid a little of the worry about the foam leaching and degrading.

But will the plants be able to reach the water when they are little, well that would depend on how high above the water the boards are suspended. Heck, in a 2" floating raft a seedling might not reach the water depending on how it's placed in the net pot. I would probably use a wick for situations where the bottom of the net pot doesn't touch the water or if starting seeds in media directly in the net pots. Others might top water the seedlings daily until their roots reach the water.

[ericjf7]

It is my hope to come up with more information as to type of material, manufacturer, and a place to buy this raft material in sheet or roll form, without the holes precut, which means the spacing and size of the holes would be up to the individual.

With regard to planting out your seedlings, it would depend a lot on the method and medium you are using to start the seeds. Many videos show the net pots being dropped into hopes in the rafts, with whatever loose medium there is being rinsed off to keep as much as possible out of the beds. If the starters are in trays with soil, perlite or such, again they show most of that medium being washed off the roots, and in some cases simply dangling the roots through the holes, in which case it would be good to have different sizes and spacing for different stages of growth, or use something inventive for spacers, initial propping etc.. This is where some of the more experienced growers would have more details.

[Michelle Silva]

TCLynx, yeah, they do look like those things! It wouldn't work for me to not have the biofilter, although I don't know how FA set up , mmine is pretty bare minimun already..so need those biofilters.
ericjf7,on larger scale it is much more economical to start with seed ..Also, FA plants their seeds directly in 2" net pots ,that method seems it would take up an enormous amount of space for a commerical set up, doesn't make sense to me. Also, plan to keep seedlings off system till they need the nutirents.

ericjf7 said:

It is my hope to come up with more information as to type of material, manufacturer, and a place to buy this raft material in sheet or roll form, without the holes precut, which means the spacing and size of the holes would be up to the individual.

With regard to planting out your seedlings, it would depend a lot on the method and medium you are using to start the seeds. Many videos show the net pots being dropped into hopes in the rafts, with whatever loose medium there is being rinsed off to keep as much as possible out of the beds. If the starters are in trays with soil, perlite or such, again they show most of that medium being washed off the roots, and in some cases simply dangling the roots through the holes, in which case it would be good to have different sizes and spacing for different stages of growth, or use something inventive for spacers, initial propping etc.. This is where some of the more experienced growers would have more details.

[Greener]

I think I'm going to stick to some sort of solid board (probably that FDA approved, UV-resistant white HDPE board) and suspend it at a fixed height in the trough on vertical PVC pipes (with holes cut in to prevent stagnant water in the pipes), and simply cut a wide overflow standpipe to just ~0.5-1" below the bottom of the board, so the water level in the raft stays fixed just below the board. I'll use net pots filled with a small amount of hydroton to wick water up to the surface. Eventually the roots will reach the water and start dangling down (above the giant prawn I'll be growing below!).

Anyone see problems with this idea?

I'd be tempted to use something like this to start seeds directly in the system, though it wouldn't be the best use of raft area. Less effort later though, no transplanting.

[ericjf7]

Response from Dow, Thanks Eric

Thank you for contacting The Dow Chemical Company.

Our STYROFOAM(TM) brand XPS product are not UV stable. The product will yellow after exposure to the sun and will be begin to powder over time. Our products are building materials and insulation, and Dow has not done any testing for it's suitability for your application.

Sincerely,

Michael, on behalf of,
The Dow Customer Information Group
1-866-583-2583
8AM - 5PM EST M-F
www.dowbuildingmaterials.com

[Giorgio]

Now...They do make marine foam specifically for water situations that is very safe for humans and animals

[Two Jay]

How many holes per 4' x 8' raft, realizing that the end pieces may be much smaller, for starting lettuces, leafy veggies etc then how many for growing them to harvest? I know I seen some good pics or a YouTube video somewhere but can't seem to find it. Thanks.

[David Hart]

Hi James, You may want to read in ...Commercial Systems.
http://aquaponicscommunity.com/forum/topics/commercial-systems?xg_s...
On page 5....look for Chris Smith's posting. He gives some great info on spacing of plants.
Hope this helps... :-)

James Kaiserlian said:

How many holes per 4' x 8' raft, realizing that the end pieces may be much smaller, for starting lettuces, leafy veggies etc then how many for growing them to harvest? I know I seen some good pics or a YouTube video somewhere but can't seem to find it. Thanks.

[Giorgio]

Hey gang....I was wondering about some lexan suspended in the water with pool noodles, will that stuff be safe for fish and plants, you can even paint it and is very tough and hard to break.
I have some leftover and I want to experiment and coat it with food grade epoxy.
anyone out there familiar with this product?
Aloha

[TCLynx]

Well, it depends on how you feel about the possible leaching from different plastics, foams, paints and coatings.
The pool noodles will break down over time and become water logged though painting them might help, ya have to do some research into safe paints that would stand up to the situation.
The lexan would need to be covered to keep sun out of the beds (the bacteria need dark to colonize effectively.)

[TCLynx]

Ok, here I go on a new experiment!

I now have a big raft bed to experiment with. Well it's not plumbed in yet and I notice the used billboard liner leaks a little where small abrasions or pin holes have damaged it but are for the most part too small to really see. Not sure if it will work long term but I'll try testing it out for a bit, I can always turn it into a bed wicking bed for dirt gardening if I decide the raft method doesn't work for me.

So does anyone know exactly what kind of paint is food safe for the rafts?

I'm going to experiment with a few different possibilities for rafts. The bed is about 36 inches wide so I figure a 32 inch wide raft would be appropriate which is conveniently an 8' long board cut in thirds. (the bed is long enough for six 4' long rafts at that width.)

I'm still a big fan of using rayon mop string wicks in net pots to allow for starting seeds directly in net pots and I've also found that a peat pellet dropped onto the wick in a net pot will stay moist enough to keep a seedling going till it's roots reach down to the water. I've found that the peat pellets stay nicely moist using capillary fabric with an end hanging into a trough of water so this is a great way to start lots of seeds in a small shelf space. I'll be testing other seed starting methods on the capillary fabric as I can.

I do like the idea (in my system since I've got plenty of bio filter and solids filter in my grow beds) of suspending the rafts above the water so that I don't need to add lots of extra aeration to the beds. However, my bed construction won't support too much weight on it's edges or allow for easy sliding of anything resting on those edges so I still need to figure some way to FLOAT the plat supports. I might try a square of sealed up PVC pipes to support a board with holes. I also want to sort out some way to float the rectangle seed trays for growing baby salad mix ans such (this sort of use might be the most useful to me.)

Looking for other creative ideas too.

[Michelle Silva]

Hi TCLYnx,
Wow, glad to hear you are experimenting more and trying out the raft system..Also glad to hear you are repurposing billboard liners, that became a contreversial issue between another member and I. Sorry to hear about the pinholes, I had read that could be an issue but didn't have that problem with mine..mine had those pockets on the sides, maybe that is why I didn't have holes. Those also came in really handy, as I slid some long rebar that I had into them and it helped to hold the liner down over the block. What did you make your raft beds out of?
Michelle

TCLynx said:

Ok, here I go on a new experiment!

I now have a big raft bed to experiment with. Well it's not plumbed in yet and I notice the used billboard liner leaks a little where small abrasions or pin holes have damaged it but are for the most part too small to really see. Not sure if it will work long term but I'll try testing it out for a bit, I can always turn it into a bed wicking bed for dirt gardening if I decide the raft method doesn't work for me.

So does anyone know exactly what kind of paint is food safe for the rafts?

I'm going to experiment with a few different possibilities for rafts. The bed is about 36 inches wide so I figure a 32 inch wide raft would be appropriate which is conveniently an 8' long board cut in thirds. (the bed is long enough for six 4' long rafts at that width.)

I'm still a big fan of using rayon mop string wicks in net pots to allow for starting seeds directly in net pots and I've also found that a peat pellet dropped onto the wick in a net pot will stay moist enough to keep a seedling going till it's roots reach down to the water. I've found that the peat pellets stay nicely moist using capillary fabric with an end hanging into a trough of water so this is a great way to start lots of seeds in a small shelf space. I'll be testing other seed starting methods on the capillary fabric as I can.

I do like the idea (in my system since I've got plenty of bio filter and solids filter in my grow beds) of suspending the rafts above the water so that I don't need to add lots of extra aeration to the beds. However, my bed construction won't support too much weight on it's edges or allow for easy sliding of anything resting on those edges so I still need to figure some way to FLOAT the plat supports. I might try a square of sealed up PVC pipes to support a board with holes. I also want to sort out some way to float the rectangle seed trays for growing baby salad mix ans such (this sort of use might be the most useful to me.)

Looking for other creative ideas too.