Hi,
my 2 cents on this is that you can use 304 for yr wfc.
Its cheaper and it works for me a little bit better.
My best Tube is a 304 one.
The reason can be that the 304 contains more nickel/chromium and those metals are better for electrolysis.
But again, these are just my thoughts on this.
Type Analysis of Stainless Type 304
Carbon 0.08% max. Silicon 1.00% max.
Manganese 2.00% max. Chromium 18.00-20.00%
Phosphorus 0.045% max. Nickel 8.00-10.50%
Sulfur 0.030% max.
Type Analysis of Stainless Type 316:
Carbon 0.08% max. Silicon 1.00% max.
Manganese 2.00% max. Chromium 16.00-18.00%
Phosphorus 0.045% max. Nickel 10.00-14.00%
Sulfur 0.030% max. Molybdenum 2.00-3.00%
http://www.bosunsupplies.com/StainlessInfo2.cfmbr
Steve