You know, there's something I've been a little concerned about...
Because I only plan to have this one 6g tank as a soft-water habitat, I've been purchasing "RO" water from my local gorcery store (instead of buying an RO system). They have a machine that says it is purifying local tap water via RO, and specifies "no additives". It sounds pretty safe, the fish are healthy, and it's $0.29/gal.
However, if it is true RO, why do I get a dGH of 2, a dKH of 2, and a pH of 7.0, consistently, when I test this water?
Anyway... Currently, no driftwood, no rocks, only HD PlaySand + laterite, under a layer of "blasting sand" (small gravel), which I purchased from my LFS.
I will pick up a mid-range pH tester, today, and get back to you.