Pond pH

PH is only a measurement of the free Hydrogen ions in the pond water and is very, very dynamic. The pH in your pond can change overnight...In particular, the pH is prone to fall, and "crashes" are quick, and fatal. Interestingly, many people say they checked the pH last week, and are surprised to find that the pH can change overnight.

In simple terms, the pH is supported in range by the carbonate activity of the water (measured in Total Alkalinity) and when the carbonates are exhausted, or overloaded, the pH plummets to 5.5 and kills pond filter bacteria and koi fish. In other situations, the pH can glide downward very slowly over months and thus your resident pond fish can survive a low pH but the new water garden pond fish you keep buying perish quickly as they enter the pond water with a very acid pH.

Check the pH regularly, and also, to get a grip on your 'safety net', measure the pond water's carbonate activity as Total Alkalinity as well. A good "buffer" will help maintain the
pH level in your water garden and koi pond.