The present study was conducted as a 2 × 2 factorial treatment arrangement in a Latin square design using 4 continuous culture fermenters. Treatments were control pH (CpH; ranging 6.3 to 6.9) or low pH (LpH; 5.8 to 6.4) factorialized with solids passage rates (k_p) set to be either low (Lk_p; 2.5%/h) or high (Hk_p; 5.0%/h); total buffer k_p was constant at 7.0%/h. Fermenters were fed once daily (40 g DM; a 50:50 concentrate:forage diet). Periods lasted 10 d, with 3 d of sample collection. Effluent samples were collected once every 24 h for 3 d and pooled. Fermenter contents were sampled at 0, 4, 8 and 12 h post-feeding on d 6. We hypothesized that lowering pH would limit methanogen ability to grow in culture, and increasing k_p would challenge methanogens to increase growth rate for survival. Further, the combination of these treatments would decrease daily methane production per total archaeal 16s copy outflow and decrease methanogen concentration in culture. DNA was extracted using repeated bead beating protocols and amplified for total bacteria and total archaeal PCR-DGGE using respective universal 16S rRNA gene primers with GC clamps. Banding analysis clearly demonstrated clustering of effluent versus fermenter samples for bacteria and archaea. However, there were no clear banding patterns for treatment combinations or for times post-feeding. Total archaeal 16S rRNA gene copies were quantified using 787f and 1059r primers using qPCR. There was no significant (P > 0.10) interaction for treatment by time, and no difference in total archaeal 16S rRNA (copies/mL) between treatments: CpH, Lk_p: 1.13 × 10⁵, CpH, Hk_p: 5.85 × 10⁴, LpH, Lk_p: 6.84 × 10⁴ and LpH, Hk_p: 4.67 × 10⁴. Daily methane production per 16s copy was not significantly different (P > 0.10) between treatments: CpH, Lk_p: 1.12, CpH, Hk_p: 0.11 LpH, Lk_p: 0.67 and LpH, Hk_p: 0.43 nmol CH₄/archaeal 16s copy. Rumen microbes are resilient to small daily disturbances in pH or slight increases in k_p, but there is a lack of clear relationship between methanogen concentration and methane production. The poor methane/copy relationship of these treatments indicates a need to move methane mitigation research beyond inhibition toward potential influencers on methanogen metabolism and growth.