SUBBED UP TOO !.... I have a two pot system too,trying with soil and perlite 50/50 for my first. regarding the clay pebbles I let mine sit for 3 days in tap water after being thoroughly washed with a shower head I did change the water on the second day (ph 7.4 from tap) they were reading ph 8 from the bag. I then let them sit a further two days in a bucket of water at ph 6 they ended up being just below ph7