About Mineral Deposits, Patina Coloration and Algae Growth
according to Lee Blackwell
A copper fountain or sculpture is shiny light copper color when it is newly made. The exception is darkness which happens near areas which have been heated to weld the fountain together.
A sculpture which is not made to be a fountain will retain a light copper color if it is coated with a clear lacquer or urethane to seal it from humidity. The coating will last longest if the sculpture is indoors or sheltered from sun and rain. The length of time that the coating will keep the copper shiny will vary according to the humidity in the environment. In Arizona in an air conditioned house the coating will last for many years and the copper will retain its shine. Mineral deposits are not an issue for a sculpture.
A fountain has the added element of minerals present in the re-circulating water which can deposit on the copper. Rubbing action and 100% humidity in a fountain is too much for a paint-like coating so there is no coating on our fountains. Due to the water present in a fountain the color will turn different than it looks when new. Exactly how it will turn is unpredictable. Your water and the mineral content of it is a big determining factor. Water can vary even by neighborhood. If the water is acidic the copper may turn blue or green. If it is alkaline the copper may turn white. It may be slightly acid with some minerals so it may turn gray green. The other factor is evaporation. If the fountain is in a very hot dry climate the water evaporates and the salinity of the water increases. In that situation it is beneficial to change the water every few weeks to minimize the salinity.
Distilled water or captured rain water is the best water for a fountain since no minerals are present. The location and size of the fountain will determine whether distilled water is a viable option.
Chemical patinas can be applied to the copper to turn it green or blue. Chemical patinas will last where the water or mist is not contacting the fountain. In places where the mist and running water is in contact the color will vary with your local water conditions.
Algae growth is a separate consideration. Algae grow most vigorously in summer when the water gets warm or hot. Algae can be controlled by using bleach or swimming pool water which is pre -chlorinated or by using an algaecide such as Fountec. Do not put chlorine tablets in a copper fountain unless the tablet is on a plate or rock to keep it out of direct contact with the copper. Another solution to control algae is to empty the fountain and let the sun dry it for a few days.
Draining rinsing and refilling the fountain with clean water helps reduce mineral deposits, reduces algae growth and keeps the fountain from clogging with organic materials such as leaves. Most of the larger fountains have drain plugs in the bottom to make rinsing easy. If the fountain is to be placed on a patio or on a level site then the drain is not a viable option. Smaller fountains can be tipped to rinse. Larger fountains which cannot be equipped with a drain can be pumped with the same pump that operates the fountain. If the fountain is pumped it will also need to be vacuumed or mopped out to really get the sediment out.
If the fountain becomes mineralized there is no practical way to remove the deposits so prevention of the minerals is the best.