I use Ilford Rapid Fixer, and mix up a gallon or so at 1 + 4, and then use the working solution as needed. And I re-use it, too. That is, after fixing a roll of film, I dump the working solution from the tank back into the jug of working solution. I replenish, or re-mix, the working solution about once a year. As the working solution gets old, I lengthen the fixing time from about 4 minutes when freshly mixed to about 6 minutes.
FS: Pentax MX, Voigtlander Ultron 40/2.0 SLII in Pentax K-mount, Takumar 100/2.8 and 35/3.5 lenses: See my ads in Classifieds
M3, M2, R2A, IIIc, IVSB2, & T, and assorted LTM & M lenses
Minolta XD11, Pentax ME Super, and assorted MD Rokkor and Takumar lenses, Rolleicord III, Rolleicord Vb, Rolleiflex Automat MX-EVS