Frequently Asked Questions
Q: When do I test for and balance calcium hardness on fresh plaster?
A: It is always a good idea to know what the calcium level of the fill water is. When starting a straight plaster pool, immediate testing and balancing of the calcium level is critical. If the fill water doesn’t have enough calcium in it (<150ppm) the crème layer could be completely dissolved. Exposed aggregate finishes (quartz and pebble) are less critical due to the fact that the aggressive start-up is used to take the plaster off of the aggregate, and as the plaster dissolves to expose the aggregate, it is increasing the calcium hardness. It is, however, still important to test and balance the calcium level.
Q: Why does my black pebble pool have white areas?
A: There are two possible answers to this problem. A calcium scale could be covering the black aggregate and plaster causing the light areas, or aggressive water could etch the plaster between the aggregate, pulling the pigment out and becoming lighter. Aggressive water is a general term that could have several reasons to be aggressive. Low calcium hardness, low pH, low alkalinity, and even low temperature could lead to the aggressive water.
Q: Why does my spa tile get more calcium on it than my pool tile, when they share the same water?
A: This could be caused by a strange phenomenon that is specific to calcium. Calcium is one of the very few elements that actually dissolves more readily in cold water than it does in hot water. If your spa is used frequently, the tile will be exposed to the hot water that will deposit the calcium as a precipitate that sticks to the tile.
Q: What do I do about the rust spot in my pool?
A: First, it would be good to figure out where the rust is coming from. If the rust is from the rebar under the plaster, it would need to be cut out and patched. Most of the time rust spots are caused by an object lying on the plaster. Nails, toys, fertilizer, steel brush bristles, metal shavings, could be the culprits. The two methods for removal I know of are acid and sanding. Acid will remove inorganic stains like rust, but will not touch an organic stain such as leaf or worm stains. Acid or sanding will work on plaster and quartz surfaces, while acid is the only cure for pebble. Acid in a squeeze bottle will work well for reachable areas. In the deeper parts of the pool, a piece of sandpaper on the end of a pole could work.