Lettuce Raft Concerns
 

I'm looking to make a raft system to grow lettuce, but I have worries about using XPS foam and plastic for the bath. Does anyone know of the leaching characteristics of the foam and plastic? Are there alternative, more natural, materials I can use beside foam and plastic. My chemist uncle has made me painfully aware of the negative effects plastic water bottles have and I just don't want the same to be true of my plants.

Well, the only thing I can add to this is that ALL of the commercial operations use some sort of foam and to my knowledge, none of them have been sued over it. I have been researching this alot in all different countries and I have not come across anybody using anything different no matter what type of system (hydropoinics or aquaponics) or applications (home farm or commercial) anywhere I look. In the end if you can find a substitue go for it and let us know how it works, if not you have to be the one to decide if its right for you. Wish I had a better answer for you.

I agree with fintuckyfarms, I haven't seen any commercial operations using water culture systems use anything other than Styrofoam sheets. And just about every part of a hydroponic system is made of some type of plastic (commercially built or home built). Sure some plastics will leach, but the general rule of thumb is to smell the plastic, if you can smell chemicals/solvents it will probably leach. But remember plants will only absorb what they want/need from the water. Just because something is in the water, dosen't mean it will be in the plant tissue/fruit. Remember the story a while back about the tomato farm in Australia that was destroyed. A pesticide was poured into the water supply, killing over 5000 plants ready to harvest. After finding out the plants were poisoned (and they stopped selling the fruit) the government tested the fruit over health concerns, and found no trace of the chemicals in the fruit.

It is up to you if you want to spend the money you can build your system using all food grade plastics. But there are people who feel even that isn't good enough like my mom who read a story somewhere, and now dosen't even want to use Tupperware containers to store leftovers in. However if you choose to spend the money for the food grade plastics, I don't think they even make a food grade Styrofoam. But you might try using cork. Like cork flooring. It's basically a wood flooring, but made from cork. Cork will float, but I'm not sure if it is a closed cell product and may absorbed moisture. However they use it for flooring, and wouldn't want it to absorb anything that may get spilled on it. So it might be a natural material that both floats, and not absorb moisture. You may want to ask some questions about it at places that sell flooring. However I doubt it will be cheep, and depending on the thickness of it, you may even need to double it up to make it thick/rigid enough.

Haha, I'm the same after seeing my uncle's results. I refuse to use syranwrap too as it's horrible for that purpose.

I had the same thought about the plants only using what they need, and that's the reason I've been using a plastic flood/drain rig. So thanks for you both bouncing back a re-assurance on the pre-harvest aspects.

As for the post-harvest side of food, an FYI, plastic IS bad for storage...food grade or not...

I don't think cork would be a good product. I believe it does absorb moisture and would probably act as a mold food...

The only two products I could see being a viable alternative to a foam raft are fiberglass and stainless steel. Obviously would cost a bit more...

Stainless steel is sure to sink, and fiberglass is likely too as well. Unless you designed the system so they are supported by something, and not actually floating. Not sure if there are many different types of cork, but cork is also used to cork wine bottles and other liquids, and from what I've seen there, that cork dosen't seem to absorb those liquids. But I would need to ask some questions from those who make/sell the cork products to know it's property's for sure.

The stainless/fiberglass options wouldn't sink if made properly...they make boats out of the stuff...

Just a thought, A pvc pipe framework (grid stile), then a thin piece of stainless over the top to support the cups.
Andre

Thanks Andre,
That gives me another idea of how to remedy a possible problem relativity easy that I may run into soon.