I can not reference the white film on the foam board. You may want to post brand name here so we can avoid in the future, but in most cases 2 inch foam board is used on most commercial farms. Thicker board is self supporting.
I would only use 2" DOW blue board for rafts:
1) lasts a long time and will not fall apart.
2) Rigid enough for a 2'x4' raft
3) Stands up to 2" hole saw well.
4) easily painted white
I'm going with Ned
Styrofoam is not worth the money for this process.
2" blue board is good, it doesn't sink under the weight of the plants.
I would suggest that you consider some suspended rafts too. Make a lip around the inside of your tote and set a panel on it. The height is fixed and can be easily adjusted with shims to figure out what works best. Studies have shown that an air gap is worth working for.
Jim, I was trying to get the rafts suspended. I took a pvc pipe, strung a line through it and put the board on top. I held high enough on the ends but the middle sagged. I am just going to have to spend the money for the better product..
Plus after taking out all my 3/4 inch pipe, I have extra to build a better support support.
The thin styrofoam is not a good plan. I am replacing mine with Dow board. Most of my system has Dow blue board and it holds up great. The thinner foam with silver reflective top is the boards I am replacing. The board gets very soggy with water and who knows what else it absorbs. I emptied the older ones about one year old first and found they were very weighted with water. The ones I had added last were not as bad but definitely on there way to being very weighted. If you have the choice go with the Dow board or you will be replacing the cheaper ones soon than later.
I use a hole saw and I use 2" pots about 5000 of them. I also have some 3" holes that I use Solo Cups in for larger plants. I burnt holes in the bottom of the red solo cups with a soldering iron (time consuming but it works well). I do that to allow for the water to flow thru it. Those are the two sizes that I use. I use floating PVC with plastic netting for mint and watercress.
Interesting about the watercress and mint...could you share some pictures?
Went out this morning and bought some blue board. Now I need to figure best spacing. I posted this in another groups so I will do the cut and paste thing and double post instead of typing everything from scratch.
I am replacing several of my old piece of crap styrofoam rafts with Dow blue boards. I also want to change my hole grid pattern and was wondering what is the consensus for the best spacing for an IBC tote? I am currently using 8 inch spacing which gives me room for 21 pots. That is 6 rows with alternating 4 per row and 3 per row. Before I commit and start drilling/burning, I wanted to see what others use.