[rossb]

I have been using abs for ... well years. On my pond outside the liner is black so I wanted black pipe. When I upgraded this year I used ABS again. The piping that I pulled out had freshwater algae on it...which is a good sign. In fact I have used bits of cut off ABS in my bio-filter for both indoor and outdoor ponds. I have also used the ABS indoors on my tanks with no problems. Just buy the cheap stuff...