Thanks Tom, like I said I have had no issues with leaks or cracks(knock on wood). I don't use anything but clear(opaque) plastic for these as you can see, and the sump is pretty heavy duty plastic, the fuge would bow if not sandwiched between the wall and the sump, the ATO only bows when filled to the max(only normally do this when on vacation, other times it is about 3/4 full. As far as plastic leaching stuff into the water, if you are concerned about the container, you could use EDPM rubber(the stuff used for ponds) to line the container, it is safe to use. More than one way to get the job done on this topic. Good luck and let me know if I can help. I have a link to "compression baffles" I don't know if it is of use to you, works with a glass tank, let me know I can post it or send it to you.
Matt