Increased Base Fog

Developer replenishment rate is too high. This is possible with developers other than Chem-Blend brand developer.
Developer temperature is too high.
No starter has been added to fresh developer in the processor.
Fixer level in the processor is low.
Developer has been contaminated by fixer.
Processor's rollers are dirty or worn.
Safelight is improper type for film.
Improper film storage.