The appearance and expected service life of pool plaster can be affected by water chemistry. A low pH acidic condition can etch plaster, creating a rough, pitted surface that degrades faster. High pH, alkaline water causes calcium deposits called scaling to form, eventually discoloring the plaster. High levels of iron, copper or other minerals in the fill water will cause stains, and frequent acid washing due to algae issues deteriorates plaster. There are basically two methods for starting up a freshly plastered pool, chlorine start, or acid start. Avoid swimming during the break-in period, and no pool cleaner use, and only light vacuuming.