Water Hardness and ph in aquaponics

Most of us aquapons know that the health of all the creatures in our systems (fish, plants, worms, and bacteria) depends on proper pH. We also know that we are targeting pH in the 6.8 to 7.0 range but that we don’t have to worry about adjusting it until it goes down to 6.4 or up to 7.8. We also know that the best way to lower pH is with an acid, and that the best way to raise it is with carbonates or hydroxides. We know that rapid changes in pH can be very stressful to fish. And we know that the pH will probably decrease over time because the nitrogen cycle produces an acid (nitric).
But often, knowing all of this and applying it to our systems are two different things. At The Aquaponic Source, we handle questions and concerns each and every day about pH. Generally, the questions fall into one of two categories: