Container question

[Kerry McMahon]

I have not created a AP system yet, still in the design phase.  However, I wanted to put together a small, mostly free/very low cost "test" system to "get my feet wet" in AP.  We have a bunch of old kitty litter containers (the plastic containers that the kitty litter comes in, not cat litter boxes that the cat uses) that we use to store random stuff in.  Would these be considered "food safe" to use for small grow beds?  The containers are labeled as being HDPE (which I understand to be "good"), but I don't know if they were made from recycled material or not (which I understand to be "bad" if they are).

My idea was to use a big, currently unused tub-style laundry basket (Rubbermaid brand I think) as a fish tank for a bunch of minnows and the litter containers as the grow beds (if this works, the minnows would later become food for the catfish in my full-size AP system).  I was thinking of having the litter containers connected together by PVC pipe so that as water was pumped into one, they would all fill up at the same time, then having the siphon drain at the opposite end as where the water entered.  The containers are small, so I could only get 1-3 plants into each (depending on the plant), but was thinking of connecting 6-9 of them together (depending on the GB/FT size ratio math - haven't bother to do the math yet since I don't know if I can even use these buckets or not).

(Pardon my sad little graphic :D )

So, the question is, can I use the kitty litter containers or are they the wrong type of plastic?