The pH range of 6 to 8.5 is acceptable for most pond life. The primary concern with pH is its direct relationship to the toxicity of ammonia and nitrite. Each pH interger above the neutral 7 reflects a tenfold increase in such toxicities.
Any pH value below the neutral 7 is considered acidic. Baking soda or ground limestone will raise the pH level.
pH values over 8.5 will definitely stress the fish to the point of disease. We receive some calls where the pond owner claims to have a pH reading of 9.0 or more, and the cause for this is cement or mortar leeching toxic lime into the water. Bricks or untreated mortar blocks used as plant pedestals, run-off water, and reconstituted materials used in or around the pond may be washing in leeched lime which can cause severely high pH readings.
We suggest you use a commercial lime neutralizer or a nontoxic pool sealant paint if you have a concrete pond.
If the pH is normally high in your tap water, we suggest obtaining more suitable fish for your pond, such as the common goldfish, shubunkin, or comet goldfish. These fish can tolerate higher (non-toxic) pH levels.
When choosing a new pump, it is important to look at all factors. Obviously, we first want to make sure the pump will provide the desired flow. Then we look at purchase price, and warranty. An often overlooked factor is the cost of operating the pump.
