I always suggest you get an inexpensive pond or aquarium test kit & use it to see how much vinegar or citric acid it takes to reduce a given volume of fresh tap water to something a little below your target pH. Your water will rise in pH as it gives gasses out dissolved CO2, so it's a little better to shoot low. After you determine how much it took, just add that much acid to that same volume of water, whenever you water. Inexpensive pH meters that can't be calibrated are extremely inaccurate, btw.

Al

Thanks, Al. I think I'll look for a test kit. Some of the aquarium ones don't go down to my target value of 5.8, but I see there are some wide range kits that do. As for the CO2 issue, I use a paint mixer to ensure CO2 equilibrium before testing, so no problem there.

Ah - you're 'all over it', I see. ;o)

Al