There is plenty of concrete evidence already given. Go to
www.yumekoi.com for more info and facts, or
www.keirinponds.com
As for the FIR, the new Navy ship hulls are based on that very thing, to reduce buildup of deposits on the hulls.
The shower itself can be made of several things. Stainless steel ones can be bought from Carl at Keirin or made at a local stainless steel metal shop. The dimensions are right on Momotaro's web site. Plastic crates are ugly, but work.