Weren't you the guy who made that DIY peat filter from the neck of a water bottle and a bag of peat? Doesn't the peat lose its ability to soften the water?
If you run peat in a filter, it would loose it's ability over time. I filter the water beforehand and what it comes out as in the end is what it stays out, +/- a 0.? pH point or so as the water off gases and settles.