i'm actually experiencing this with my mixes that i've recycled for about 18 months now, and the peat seems to have lost its acidic quality. I have a couple fresh batches of soil that i'm trying out, if my yields go back to normal and pH goes back to normal, i'll be cutting all my old mixes with fresh peat, and just deeming everything else as compost that's in the mix (with drainage being an exception). So soon, i will find out if that's what's really going on. in the mean time, with my mixes that are showing a slight alkaline pH, i'm making a peat extract "tea"... just straight rinsing peat with water and using that water as a source for protons, hoping to acidify my soil with those proton dense waterings. was pH'ing my waterings at ~6.0 with the peat extract... so hoping to see some increase in acidity after this week (did two waterings like this).