in order to compare Ph and flucuations we need to consider, ratios and ppm
as well as starting water quality
otherwise its apples to oranges
I have been reading all of the posts here, and don't see a sound answer to the Ph drift, maybe just stupid or too old

TT it looks like what you are doing works very well:thumbsup:
do you use any additives? ca/mg, or sweet of florisous plus