Few things that have come up.
@ Jim, etc... You're right that "fish safe" isn't something that's especially well defined. The USDA and FDA folks haven't put much in the way of regulations out there. Their rule of thumb is that if it's "potable water safe" it's "fish safe". He folks at Langston University and ATTRA are helpful about this stuff.
@ Aquaman. Check out my drawing here. Insulation with net pots through it. The insulation will sag in the middle. I prop it up with bricks set in the media.
I have the liner all laid out on the lawn and washed down but man I hate the vinyl odor and I am stalled as to what to do. Outside of that it would work great. I don't know if that "new plastic" odor will ever go away. I may go back to the white poly as I don't remember smelling anything chemical about those.
Jim, it might set your mind at ease if you can find out what the liner is made of. Then you could google that material for information about its safety related to food or fish.
I think you made the right choice. Potable water safe really ought to the standard, at least for those of us who promote aquaponics. I'd had to discover some cancer that's caused by fish raised in non-safe containers. I'm thinking of trying to move away from PVC with my next system.
Since we've got a good long random thread going, I thought I'd pose the question as to what you think these freezer to fish tank conversion kits are worth? I'm thinking of reducing the price, but don't want to go so low they're not worth making. I'm debating whether to keep focusing on these or to start working up something else.
It's kind-of on-topic, at least with the fish safe issue
Ok as far as PVC does plumbing PVC use in most homes and sold at most stores is safe. The PVC that is not safe is clear flexible plasics like salad shells and food packaging and stuff like that can break down over time. Congress passed a law in the end of the 90s regulating pvc piping and its contents.