Heres my answer to the problem in a 13 gallon 7.6 tap water tote. Put water in tub, add ph down, get it down to about 5.2-5.4., add nutes (i use ph stable nutes) . Aerate with some stones for 2 hrs, recheck ph. The water company told me calcium and chlorine in water. Calcium buffers ph back up of course, so the ph is always up. Add more ph down to get it to 5.4 again (doesnt take much), and set the damn thing into motion. Chasing your ph is a nightmare, DONT DO IT!! My epic nute company talked me thru it, and a ph swing UP can be a good thing! As it swings THRU the nutrients range, all the nutes become available! Don't freakin' chase ur ph!! Bigger rez IS easier to stabilize, but bigger also means more of whats buffering you back up. Have you tried 30 gallons? I try to push the least water, saves me nutes and work.
After about 3 days with the air always running in the tubs (no bacteria,mold,haze here!), my ph is usually up around 6.2. I add more ph down until I hit about 5.6, and walk away! 4 days later when I change out, the ph is usally about 6.2-6.6, perfect!! I read about "dont change the ph too drastic" and all that. Well, mine goes from 6.4 down to 5.2 in the time it takes me to carry 30 gallons of water. Only once did I see a ph leaf issue, and that was when my ph meter blew upon nute change. I hate buying ph down, but since my fav hydro shop DOES pay its employees from my pocket, it lessens the hurt. That, and setting up a RO in a rental, or buying water just isnt cost effective for me.. Catching rain... not in this yard. I have had wondeful results with my tap water. MAybe pure would be better, but not feasible...yet. *cmon ph perfect nutes!!! Please dont be bullshit!!
O' btw, Ive read a TON of articles on chlorine. My water company uses liquid bleach. The ppm in my water is around 125. From what i have read, chlorine kills bacteria and mold ect.. It also disappates quickly. I used to use hydrogen peroxide, but learned it binds quickly and gets nuetralized. I also used to let my water sit out for days before using. I decided I'd just run it fresh, use the chlorine to keep my media clean, and in 48hrs it's be gone anyhow. So far, in practice, this logic holds true. I dont recall whos article got me here, but the science behind water baffled me so much i decided to just use the shit outta my tap. Workin so far and feelin' good about it too.
I am now so comfortable with the way my water acts. One time i went to check my ph... it was down??? WTF!! I knew something was wrong. I looked at my chart, it had been 12days since nute change. My guess is.... the salts or waste were building. I did a fresh nute change. BOOM, grew like magic again. Never afforded store water, does it react the same? Always thought the buffers in my tap water would stabilize my ph (once i got it where i wanted it). Anyone got any info to share?