Mineral Presence

• No swimming pool owner wants her pool's water to be anything but crystal clear, and she expects her pool chlorine tablets to guarantee that. However, pool chlorine tablets added to pool water that suffers from elevated mineral levels will turn that water one color or another. Unfortunately, water going into a swimming pool can be afflicted with oxidized minerals and metals such as iron, manganese or copper. Chlorine chemically reacts with minerals in pool water, coloring that water as a result.
  
  

Tests

• To determine whether minerals in your pool's water are causing it to turn yellow after chlorine tablets are added, you will have to run several tests. In all cases of yellow pool water, test for pH level, total alkalinity, heavy metals, total dissolved solids (TDS) and hardness. Many pool water chemistry levels can be determined by using a good pool test kit. Reputable swimming pool supply stores can also test pool water samples for all pool water recommended chemical and mineral levels.
  
  

Initial Steps

• If minerals in a swimming pool are present in high levels, make sure pool chlorine levels are between 1.5 and 3.5 parts per million (PPM). Also, make sure the swimming pool's pH levels are between 7.2 and 7.8. Pool pH below 7 and above 8 will seriously throw off a pool's water chemistry. Pool total alkalinity level should be at 110 PPM, because chlorine tablets are stabilized. Stabilized chlorine tablets are acidic and will reduce pH and total alkalinity.
  
  

Treatments

• When metals or minerals are present in a swimming pool's water, use a metal sequestering agent to eliminate them. Add metal and mineral sequestrants to a swimming pool only after adjusting the pool's chlorine, pH and alkalinity levels. Also, run the pool's filtration unit for approximately 12 hours, and then shock-treat the pool, letting it sit for eight to 12 hours more. After shocking a pool, retest the pH and alkalinity once again, and raise the pool hardness to 200 PPM if it's low.
  
  

Considerations

• If a swimming pool's water still turns yellow after metal sequestration and chlorination, replace at least one-third of the pool's water. When replacing swimming pool water, make sure it's from a source that's free of metals or minerals. Unfortunately, well water often has a high minerals and metals content and can react with chlorine tablets, but using a sequestering agent for a swimming pool will help. Lastly, metals and minerals in pool water often leave stains, which are a sure sign of their presence.