Floating raft bed alternatives

[Juniper Rivers]

Hello friends,

 

I am trying to find an alternative to polystyrene floating raft beds and am curious if anybody on here can point me in the right direction.  I remember seeing a youtube video months ago where some people were using raft beds that appeared to be made out of plastic and fit together almost like a puzzle in an interlocking fashion.  These seem ideal and I would love to find some for a closer inspection.   Any information or help would be greatly appreciated.  Thanks!

[TCLynx]

Well they do use paraffin in food.  I don't know that the wax will hold up long term against sun but it might take care of the edges and bottom for a period of time.  However, I won't guarantee that some of the microbes in our systems won't eat wax.

 

I would definitely recommend testing this on a small scale before assuming it will work and doing much large scale planning based in it.  I'm not sure how well the wax will stick to the foam.  Should be really easy to get a chunk of paraffin from the grocery (in with the canning supplies usually) and a small sample of the foam you plan to use and add some plant holes so you can see how well it coats the different surfaces.  Use a double boiler to melt the wax without scorching/burning.  Paint it on and let it cool then see how it works.

 

You may have got the idea from people who have used wax to waterproof concrete.  It is an idea that works but it is incredibly tedious to melt the wax and then have to heat it in with a torch or heat gun to get it to absorb into the concrete.

[Claudio J Tracchia]

How about using fiberglass boar, some people have concern of the resin bleaching with time, not being prove yet. two or three layers of 5/16 cloth will be strong like plywood

[Nate Storey]

In my experience, the wax will simply break off the board and cause problems for you later.  It won't flex with the blue board, so unless you can keep the boards perfect, it won't probably work that well.  That and I anticipate it will be a pain in the butt applying it to the blueboard.  Aleece mentioned sealing concrete with it- it works because concrete is somewhat porous and will accept melted wax.  I think it will be a problem with polystyrene.  I have a raft design that I've been working on- I'll show some pictures soon.  It is based on bottles but is way more stable and allows adjustment of raft height via adjustable air siphons.  I'll try to remember to get pictures up as soon as the prototype has been tested and confirmed to work.  I think it might end up being cheaper than blueboard.

[AJ Grottke]

Great, thanks for the info TC and Nate.  That raft prototype ya got going there sounds interesting, update as you progress.

[Nate Storey]

Will do.  I'll post designs when I'm done with it, so that other folks can replicate it.

[rosaanniey]

Sounds good to me. Sorry to say that i do not know much about this, but it seems to be deserve some attention.

 

[Ron]

   Ive been thinking about this and a rail on each side with you sliding the tray down as it grows and new trays placed at the one end.Ill admit im new at this but as long as water is circulated and there is a upper level drain.to keep the level of the water at a certain height? Im trying to figure out what i want to use.Im for a system that has no gravel or medium to deal with.

 

[TCLynx]

If you have no gravel or media to deal with, you will then need to deal with some other sort of filtration.  Remember that by lifting the rafts off the surface of the water you are removing almost half of the surface area that the bacteria would otherwise colonize and if you are lifting the raft off in order to save on aeration, you will really want to make sure you don't have lots of solids ending up in the DWC beds since they would rob oxygen and create anaerobic zones.  So by avoiding gravel you will likely need to add some sort of solids removal and extra bio-filtration that will require more regular maintenance.

[Vlad Jovanovic]

I thought about fabricating some rails with rollers (plastic rods, tubing and some flatstock) out of PTFE  to screw onto the top of the top-rail of my DWC troughs. They'd have to have a tiny 'toe-kick' to keep the rafts from potentially veering off course and a bottom guard (thin plastic) to keep the water from evaporating out into the air (mostly to keep the air-space that the first couple inches of roots would be exposed to nice and humid).

I may actually try this on one trough if I get the time (and some extra money) to fabricate the rails/rollers this winter. Not so much an attempt at avoiding polystyrene for now, but one of passive aeration to the root zone. I figure if I can create an inch or two of air space between the bottom of the rafts and the top of the water, I should hopefully be able to do without all those air stones, air pumps and electricity. Keeping this air space has worked real well in some small test systems, but my big troughs are almost 38 feet long, and I don't have the balls to try it just yet. Anyways...

With such a set-up, you'd no longer be tied to a material that had to float...the rafts would still be mobile...and you wouldn't need all the electricity, diffusers and pumps...

[Chris Carr]

Without investing in rails and rollers, how important is it that the system is a first in last out assembly line? Would it not be an easier test to have your harvesting 'station' mobile assuming you only harvest a few rafts at a time? Again this isn't ideal by any means but easier to implement temporarily and cheaply with some static rails and a cart. Later if you wanted to have the assembly line going and can invest in smooth enough rails/rollers that you can shove the whole trough down, then so be it. If it doesn't work out, rip out the temp rails and drop them back onto the surface :)

[Ron]

  Ok, Chris if you want to do it the easy way! So now its how to hold up trays and ive already been reading many opinions on having the rafts in the water,just touching or with the roots half in and half out?Im trying to learn.

  Im just for something more solid and long and lasting than foam.The small beads that come off could end up being a pain also.

 

[TCLynx]

The truth is, if you are not doing 4' by 8' rafts, smaller rafts can easily be lifted out and carried to a harvesting/planting station in the shade so having them float along is not Mandatory though is does make certain things easier (organization of keeping track of what should be harvested next and so on.)

Of course boards of wood or other heavy material that can support full size plants across a wide DWC bed may be harder to lift and carry, especially if you are trying to pick it up from just one side of the bed rather than lifting it out at the end where you can have people on both sides without having to walk along and drip on all the other plants.

But for a small scale (backyard or trial system) you really don't need the assembly line thing going on if super efficiency isn't that big a deal.

The biggest reason to do the assembly line is so that you can delegate (talking larger farm operations) the planting/harvesting activities to workers.  If the instructions are too complex involving figuring out which rafts are meant to be harvested and where to place the newly planted rafts, don't expect your labor to do it without you being right there to supervise (and at that point you might as well be doing it yourself.)

It can be really difficult to find good farm help and I tell you the volunteers are sometimes the worst.  They want to be there but they tend to want to do what they want to do and only when they want to do it and only how they feel like doing it so sometimes they are more trouble than they are worth but it seems rude to tell them to stop helping and go away since they are volunteers.  At least with paid workers, if they don't do what you want them to do and how you want it done, don't keep paying them to come back.

Sorry, that got really off topic didn't it?  But basically the whole point of the rafts is to make the labor easier.  If you are going with heavy wood boards full of plants, you probably will need a cart to move them around even if you are doing the actual work of harvesting and planting in a more comfortable place.  (as noted most actual rafts don't have a planting location at one end and harvest at the other, they usually carry the rafts to a comfortable workstation to do those activities.)  Be sure to design your place so the pathways to those workstations are clear and big enough to carry the rafts or roll your cart with the boards.

That might be the biggest issue with not working out of the ends of the troughs.  In high value greenhouse space you might want to make the pathways narrower between troughs.  You still want pathways so you can spray and inspect plants and do what tending has to be done during the growing cycle but the pathways between troughs just need to be big enough for walking with the sprayer.  If you have to be able to wheel a 4' wide board on a cart through the pathways, you need wider walkways at least every other trough and that can eat up high value space if you are doing greenhouse production.  Outdoors under the sun it may not matter nearly so much.