Raft Material

[15mules]

Ok, I have used the search option and have not found anything specifically addressing this issue, I know most backyard type AP systems are using media beds, but I thought I would add in what I have found out about raft material and certainly invite anyone with any additional information to feel free to add it to this discussion,.

From my research I have found it is generally agreed on that the Owens Corning "Pink" insulation board contains harmful chemicals and should not be used as raft material. I also found that there was a short time they changed their process and it was ok, but now for whatever reason (financial I suspect, as their product is cheaper than the Dow "Blue Board") they have changed back to their original process and it is still not recommended.

Dow "Blue Board" is one of the raft materials recommended by many, as being suitable for raft use, as the chemical makeup and manufacturing process have proven through use, to not be harmful to the fish. This sounds simple until you visit the Dow website and see they have well over 20 (or more) variances of their "Blue" insulation board. The question now is "Which one do I get???" Well, I have found there are basically two types, by trade name that are suitable, in my opinion. #1 the best and most expensive is Dow "Square Edge". Square Edge is the trade name and it only comes with square edges and is rated at 25psi. This board is thought to be more durable, because of the high psi rating from everyone I have talked to. The #2 choice is Dow "Utility Fit", it is rated at 15 psi. Be careful here as the Utility Fit comes in square edge, stepped edge, and also lap edge. You will want to specify the square edge configuration. But that is not all!! There is more options!! It also comes in what is called "Score board". The insulation is scored length wise on 16" centers for ease of breaking in the construction use, which means it would easily break while you were using it also, which would not be good. So you do not want score board. These are the only two Dow products I know of with the right makeup and configuration for raft material, as recommended by others actually using it, some for over 5 years, with no harmful effects, and good durablility.

Plain closed cell 'White' insulation (the stuff that looks like it is made up from million of little balls pressed together) This stuff is really cheap to buy and can be used, however every time you handle it the little balls rub of so it is kinda messy and probably would not have a long life?? But it is cheap. It also may be difficult to find in 2" thickness at your local supplier, most home improvement stores generally carry it in 1".

Most any of the insulation material listed above is not UV resistant, so you may consider painting the tops of the rafts with a FISH safe, UV resistant paint to protect it from the sun? I will also mention as this has been argued many times over. If you call Dow or any of these companies, (read carefully here) "They will not recommend their product for this use, rafts for AP that is) Please understand it is made for the construction industry as insulation, all of their testing has been for this use. The company would be held financially liable if they recommended their product for ANY other use than this. AP is not their target market for this product, they have not tested for this market and they will not recommend it for this, but that is not to say it is not safe and suitable. Years of use in AP use has proven it to be a good product to use.

At present July, 2013 ballpark pricing for these materials are as follows

- Owens Pink insulation 4'x8'x2" sheets about $28 to $32 per sheet
- Dow "Square Edge" 4'x8'x2" sheets about $38 to $42 per sheet
- Dow "Utility Fit" 4'x8'x2" sheets about $34 to $36 per sheet
- White Styrofoam I do not have an estimate on this but it is cheap probably less than $20 per sheet

Just as a side note, as I do not have much info on it. There is a company that makes pre-formed (already has the holes for net pots and everything) rafts, but my understanding is they are relatively expensive to ship because of the bulk?? You are also limited on plant spacing as they are pre-drilled (the plain insulation board allows you to make spacing whatever you want)

I have also found it is generally recommended the 2" board is the choice for good, floatation, durablity, etc. this seems to be the preferred thickness, by most.

Hope this is of help to some one it is information I would have like to have had a month ago. I have both Dow "square edge" and Dow "utility fit" ordered and as soon as I get a chance to do some testing next month, I will let you know what I think of the comparison of the two.

Please note: I do not sell or personally endorse any of these products or companies, just sharing what information I have.
Thanks for listening

[eddiemigue]

Thanks for sharing.

[Oliver]

The assumption in using rafts is that 1) they need to float, 2) they need to be rigid and 3) that it is the same material that does both one and two.

If you remove the box around those ideas and find something that floats and is safe, and something that is rigid that doesn't need to float, attach them together and now you have a safe floating raft that has a rigid top for drilling holes and plant support. The floating material could be bubble wrap, if it is safe. The top could be fiberglass reinforced sheeting that is used in showers.

Just some suggestions,

Oliver

[15mules]

Oliver,
Thanks for the input, a very interesting idea. Use two products for two different jobs??? I will have to think on that some. The cost of the raft material is a considerable cost at the moment as there are not a lot of proven materials for this to choose from. I should add that is readily available to everyone.

I think we also have to add in a few more criteria, durability (we do not want to have to replace them very often, unless we had a very cheap source of used materiel, such as packing material etc. from some industrial or commercial source?? There is an idea.
I think the second criteria is the ability to clean the rafts of algae etc. as eventually they will need to be cleaned, but I guess that really goes back to durability, when the chosen material is used as rafts.
I think the third thing we have to deal with, or ask ourselves is. Why am I doing AP to start with, and how much time do I have to build rafts?? If it is a hobby or experiment, then we can take all the time we need to try different things, as we are more concerned about the travel rather than the destination. If we are more concerned with the plants and food production, then I think it makes more sense to use something proven and get to producing sooner. Neither is right or wrong, just two different paths to a similar place.

Lets also keep in mind the 2" material also holds your plant root system (the top portion) out of the water a bit allowing it to get some oxygen before it reaches the water. The water must actually wick up to the pot. We may have rotting problems if our rafts are thin and submerge the entire pot in the water.

[davidstcldfl]

Plain closed cell 'White' insulation (the stuff that looks like it is made up from million of little balls pressed together) This stuff is really cheap to buy and can be used, however every time you handle it the little balls rub of so it is kinda messy and probably would not have a long life??

I use this type of foam. It can be made denser/stronger. It has a pound rating. They take a cu ft of it and weigh it, that's what the rating is based on. The cheap stuff is 'one pound'. It also can be 2, 2 1/2 and 3 pounds.

I wouldn't consider using the 1 pound...at least a 2 pound. The 2 1/2 and 3 pound is very strong. In my opinion...the 2 1/2 pd is as strong as the Dow. The 2 1/2 costs about the same as Dow
When I order it, I ask for 'virgin' foam...no fire retardants or bug poisons.


Lets also keep in mind the 2" material also holds your plant root system (the top portion) out of the water a bit allowing it to get some oxygen before it reaches the water. The water must actually wick up to the pot. We may have rotting problems if our rafts are thin and submerge the entire pot in the water.
In my rafts, the bottom of the net /slit pots actually just touch the surface of the water. The pot's bottom is flush with the bottom of the raft.
By the the time I'm placing the plant into the pots, the roots are staring to come out of the horti-cubes ( mineral wool cubes). With the bottom of the pot touching the water, you know the roots are also.

I use thinner rafts for new plants and move them to thicker ones as they grow. The thicker ones also have their holes further apart. This way, I'm getting the most use out of the valuable raft bed space and saving costs on the raft material.
When using 1" or 1 1/2 " rafts, I just use a smaller hole saw, so that the bottom of the slit/net pot is just touching the water.


I've never really experienced any 'rotting issues', but if your looking for added oxygen....
I've been wanting to try this. It's on the 'list'...just haven't gotten there... ;)
The hydro guys use a raft type set up called the Kratky method....


The 'raft' isn't touching the water. It's normally sitting on the edge of the raft bed.
The 'raft' would just have to be stiff enough to support the weight of the plants.

Since the roots of the new plants wouldn't reach the water, I'd use a string from a mop, as a wick for each net pot. It works...I've done it with NFT tubes before. Cotton mop strings rot in about a month, but by then, the roots are into the water.

oDYeffYcVkY

http://www.youtube.com/watch?v=oDYeffYc ... t2vXc3AkMs (http://www.youtube.com/watch?v=oDYeffYcVkY&feature=c4-overview&playnext=1&list=TLnt2vXc3AkMs)

http://www.ctahr.hawaii.edu/hawaii/down ... ettuce.pdf (http://www.ctahr.hawaii.edu/hawaii/downloads/Three_Non-circulating_Hydroponic_Methods_for_Growing_lettuce .pdf)

[davidstcldfl]

Here's another way to 'raft'...

We started this bed for our tomatoes. It's 2 feet wide and 1 foot deep. We have a lattice above it, at about 10 feet. You can see some of the strings hanging down.

We are using rafts, but, we are using 6 inch pond pots filled with a mix of coir, a pinch of worm castings, bat guano, and azomite.
The bottom of the pots are just touching the water. So a few roots are getting air through the dirt in the pot....and the rest are getting 02 in the water.

I took this picture yesterday. Tomato season is pretty much over in central fl...so we now have okra growing here. You can see, they seem to be doing well....

http://i931.photobucket.com/albums/ad157/davidstcldfl/Okrainrafts_zpsebf18be2.png (http://s931.photobucket.com/user/davidstcldfl/media/Okrainrafts_zpsebf18be2.png.html)

[dead_sled]

Here's another way to 'raft'...

We started this bed for our tomatoes. It's 2 feet wide and 1 foot deep. We have a lattice above it, at about 10 feet. You can see some of the strings hanging down.

We are using rafts, but, we are using 6 inch pond pots filled with a mix of coir, a pinch of worm castings, bat guano, and azomite.
The bottom of the pots are just touching the water. So a few roots are getting air through the dirt in the pot....and the rest are getting 02 in the water.

I took this picture yesterday. Tomato season is pretty much over in central fl...so we now have okra growing here. You can see, they seem to be doing well....


What are the "rafts" made of? Is it floating on the water or is it spanning above the water level?

[davidstcldfl]

Hi Dead Sled... :)

In the picture of the okra...the rafts are 2 1/2 pound foam, 2 inches thick ( they might be 1 1/2 thick) They are floating on the water.

To make the holes...I put the bottom of the pot on the raft...then drew a circle around the pot. I used a jig saw, with a scroll blade. The pots fit snug into the holes.
Once the plants start getting big, we support the weight by strings hanging down from the lattice.

For those that like to 're-purpose' items....the lattice is actually sides from baby cribs, that didn't meet the new safety standards. We got them for free.

[dead_sled]

Very cool. Thanks for the clarification.

[davidstcldfl]

Your welcome... :)
The 1st picture on page 2...shows the bed with tomatoes.
New work @ Sahib Aquaponics (http://www.diyaquaponics.com/forum/showthread.php?1333-New-work-Sahib-Aquaponics&p=17320&viewfull=1#post17320)
That was in nov, by spring, they were up and over the lattice.

[15mules]

Thanks for the info on the White Styrofoam. I never really ask if they could get different grades of it as far as PSI. I guess I just thought Styrofoam was Styrofoam? I will have ask about that. In the mean time I have one bundle of Dow 2" Square edge and one bundle of the 2" utility fit ordered. The guy at the lumber store said it may take 4 to 6 weeks to get, I am hoping to have it by the end of the month???

[davidstcldfl]

You might do a search...you may have a styrofoam manufacture in your area.
I've also used White Cap (HD supply) to get some....you may have them in your area too (?)

[15mules]

Yes, I am aware of White Cap, a concrete supply company. They have a lot of stuff. The local lumber store I use is owned by two brothers who live here locally and I have known most of my life. They had a small store then were able to lease the old Walmart building and now have a really nice store. This has kept the Home Depot and Lowes out of town. I do my best to buy locally and help them out when ever I can. I have also found many times if I find something cheaper in a surrounding area, by the time I figure in my diesel and the time lost driving there and back, I am just as well off to pay a bit more and buy it locally.
I hear people all the time complaining that our little stores went out of business when the Walmart came in, and I am constantly telling them it is the peoples fault, not Walmart!! If people would have continued buying from the locally owned stores, Walmart would have left, not our local businesses. I am a firm believer in supporting local business.
Sorry, I guess I got a little of topic, but this is something I truly believe in, we must take personal responsibility for the large corporate stores taking over, our choices as consumers have made it possible.

[davidstcldfl]

Yep, I agree. I use the 'local' harware store too, when I can... :)

The syrofoam ( I use) is made in central FL...about an hour away.
But I order it through white cap...they go get it and bring it to me for a small fee. Like you said...saves my time, fuel, and wear and tear on the truck... ;)

[15mules]

David do you know a trade name for the Styrofoam you use. I know you said it was 2 pound, but if I had a specific trade name or designation I could ask my local guy if he could see if he could get it.

[davidstcldfl]

The type of styrofoam is EPS....Expanded polystyrene.
Remeber to request...virgin...no bug stuff or fire retardent

[15mules]

I got it I will let you know what I find. I looked up what the White Cap store has and all they have listed is the Dow blue board, they are also 125 miles away!!!!!

[davidstcldfl]

they are also 125 miles away!!!!!
You know how that goes...if you didn't bother checking, they'd be 12 amd 1/2 miles away.... :P
I did a quick search ...I typed in... EPS manufactures in AR.
Several results showed up...I saw one site, listed 12 companys. You might find one not too far away... ;)