Cloudy or Unclear Water
Pool water can turn cloudy for a variety of reasons. The most common cause of cloudy water is either dead algae floating in the pool water or other small particles floating in the water or high alkalinity. The best way to treat cloudy pool water is shocking the pool with granular chlorine and filtering the water 24 hours a day until it clears.
Algae are microscopic plants which can transform your pool water from clear blue to a swamp in as little as 24 hours. Algae spores are introduced into the pool through the air, from rain water, and from swimmers walking across the grass and then jumping into the pool. Algae blooms are common after heavy rain showers and when the pool water temperature is high. The most effective way of preventing algae growth is to maintain a free chlorine level of at least 1.5 ppm at all times, run the pool filter 10-12 hours in the summer months, add a preventative algaecide or have the pool on a borate program. If you do develop algae, apply the appropriate algaecide, shock the pool, and brush down the entire pool causing the algae to become suspended in the pool water. The next day, if anything settles out, vacuum it out.
Tinted Water and Stains
If minerals are present in the pool water, they can cause the pool water to turn green, brown, yellow, and even purple. The water would look clear but discolored. It can be very difficult to distinguish between green water caused by green algae and green water caused by a mineral problem. A telltale sign of a mineral problem is the discoloring of the pool water shortly after shocking the pool. If this occurs, you will need to add a mineral sequestering agent to the pool. Exactly how much is a guess. We have seen cases where one bottle has solved the problem, and others where multiple bottles were needed. Mineral problems are a tough nut to crack and the pool industry is just now trying to get a handle on it. Persistent stains might need to be treated with an "on contact" product that must be applied directly to the stained area of the pool. If the stain is on the bottom of the pool, applying the product directly on the stain can be tricky, but possible.