Suggest you do the test once or twice more to confirm the pH differential between tap & ageing remains around the .5 level.
What's the pH in your tank ?. Is it around the 8.0 level ?
You should be ok without ageing with just a .5 difference, assuming that your wcs are in the area of say 50% or so, or even larger. The blend of the two (tank & tap) will not occasion more than a minor differential.