Andiejj said:
Hmmm I am not sure what metal stains look like. I have lime stains on the tile, where the water fall is. What do metal stains look like?
Iron is usually brown to tan and an easy check is to hold an ordinary vitamin c tablet on the stain. If it is iron it will disappear in a about thirty seconds. The stains are easily treated with ascorbic acid. Iron can make the water yellow to rust colored. If the pool has a blue surface, as many do, the water will have a green cast (yellow + blue = green). Iron staining is most common in fiberglass pools but can occur in any type of pool. Iron stains ofen occur from using salt that contains anit caking ingredients (yellow prussiate of soda--an iron salt). This is why I like the larger crystal solar salt for pool use. It will not contain this ingredient! some of the finer salts might contain it and not list it on the label!
Copper can produce grey, black or brown stains. The grey and black ones are very difficult to remove. It can color the water green. (clear green, not the cloudy green associated with algae. Copper usually is introduced into the water from algaecides, ionizers and 'mineral' sanitizers, and copper heat exchangers in pool heaters if the pH drops too low. Sometimes it does come from the water supply, expecially if copper plumbing is used.
Manganese produces grey stains. They are fairly easy to remove with oxalic acid or possibly ascorbic acid (test with the vitamin c tablet first to see if the ascorbic acid will work.) It can color the water pink to lanender to purple.
Cobalt spotting only occurs in fiberglass pools. It starts as tiny black spots in the gelcoat that continue to grow. It is usually treated with oxalic acid or ascorbic acid. Most of the newer gelcoats are more immune to cobalt spotting and there is some evidence that maintaining a calcium hardness above 150 ppm helps prevent it from occuring.
Coloration of water from metals will usually happen right after shocking so if your water turns a color after shocking suspect metals.
Lime (usually called scale) is also a metal stain. The metal in question is calcium (yes, calcium is a metal!). It produces tan to white stains on pool surfaces. High pH is the most important factor that leads to scale deposits. Scale is difficult to remove and in worse case you must acid wash. Lowering the pH for several weeks with constant brushing sometimes helps as does a no drain acid wash procedure. Some commercial calcium hardness reducers and scale removers are sometimes effective. Spot scaling on tile can often be removed with a pumice stone or by acid washing or a combination of both. One thing I have found effective is a mixture of tile soap and muriatic acid for removing scale from tile. Use 1 part muriatic acid to 5 parts of tile soap.
Hope this helps