What are the differences between Seahorse XF Base Medium (without phenol red, p/n 103335-100) and XF DMEM Medium pH 7.4 (p/n 103575-100)?

Both media are of DMEM composition and contain NO phenol red.  However, XF Base Medium (without phenol red) does NOT contain HEPES buffer and requires adjustment of the final pH value to 7.4 after the addition of supplements and/or HEPES, followed by filtration to ensure sterility.  XF DMEM Medium pH 7.4 contains 5 mM HEPES and the pH of the medium is pre-adjusted to 7.4.   This media provides consistent buffer factor, allowing quantitative measure of ECAR and accurate calculation of Proton Efflux Rate (PER).  When used with XF supplements at the recommended concentrations, no pH adjustment is required after supplements are added.   Seahorse XF DMEM medium pH 7.4 is recommended for and compatible with all XF assays.