I think these sorts of readings are why Andreas Moritz always is so adamant that people get colonics or colemas, after the flush.
(I don't do either, but I *do* take the salt water flush, and keep it up, for some time after.)
There's no doubt that some of the stones and chaff, etc. can work their way through the colon quite slowly, and may even be reabsorbed (ack!) before ever making it out.
Sometimes it seems as if we view the body as a bunch of stuff in a container that gets shaken up, loosened and emptied, as if it were a can or a rubber tube that just needs a good whack to clear it out.
Obviously, it's alot more complex than that.
*by the way, 6.2 for urine is very low. So, already there was a big burden of acid,
and a lack of mineral buffers. and it's not surprising that after the flush(es) the ph dipped even lower. >> A pretty good sign it seems that lots of good minerals and greens are needed, as you yourself already said.