I've used both the blue and pink stuff at Home Depot and Lowes. They both work fine. 1" thick.
Thamks Jeff I was using the white and another Aqua Frend said it would leach out chems that were harmful to bacteria.
The white isn't usually a dense as the other stuff and won't hold up as well.
I have some that is I purchased from an existing commercial aquaponics farm that is 2 inches that is a dense (like the Pink stuff at Home Depot) but she told me that to make sure that you paint the top side with 2 or 3 coats of latex paint to keep it from breaking down.
I haven't noticed any breakdown indoors or out with no paint. Matter of fact I just saw a show on Modern Marvels about Styrofoam and they said it doesn't break down. That's why they use it for building road bases now.
Clark, I would save the 2" stuff for insulation if it's big enough. I'm not sure your net pots would reach down far enough through it either.
I used the white stuff while it did not break down...But it did seem to absorb water... when I used it in my raft beds it was kind of light going in but when I went to take it out 6 months later it was seriously heavy....No issues other then that...
I didn't notice any absorbsion problems with the pink or blue stuff probably because it's more dense.