Backyard Aquaponics
A place to discuss aquaponics

I just found this thread and read through it really quickly. Sorry if I am repeating things that have been discussed already.

At my work we use 3D printing for lots of stuff in the medical field. With acetabular hip shells you can print various porosity to get better bony in-growth and fixation rather than using a sintered type bead. So you could definitely print a porous surface. You could grow a tube or baffle that has a very rough or high surface area. You can also print stuff in Stainless Steel and Titanium, which I am pretty sure is safe for the fish in AP systems especially salt water ones.

If you are going to use a printed plastic in your system it would be best to use a USP Class VI or ISO 10993 or obvious Food Grade plastic. We use a polyamide/nylon 12 for custom drill guides used in knee surgery that are derived from CT scans. This type is used in food type containers too. Only warning I've seen for this is it is not safe for holding high proof alcohol.

You are also able to print stuff out of ceramic too.