This will probably sound like a dumb question. I know PolyVinylChloride is okay to put in an aquarium, meaning it won't hurt plants or fish, but at my building supply store, I could get only ABS (pipes/elbows). Is there a difference, i.e. is ABS also okay to put into an aquarium? My little clown loaches, in anticipation of soon occupying their ABS "caves", thak you. Gitte