A saltwater pool is a type of swimming pool that uses salt instead of chlorine to sanitize the water. A salt water chlorine generator (SWCG) converts the salt into chlorine, which then kills bacteria, algae, and other contaminants.
However, sometimes the free chlorine level in a saltwater pool can be too low or too high, affecting the water quality and safety. In this article, we will explain what causes free chlorine levels to fluctuate in a saltwater pool and how to raise them when they are too low.
What is Free Chlorine and Why is it Important?
Free chlorine (FC) is the amount of chlorine that is available to sanitize the water. It is measured in parts per million (ppm) and should be maintained between 1 and 3 ppm for optimal water quality. Free chlorine can be affected by various factors, such as:
- The amount of salt in the water. The ideal salt concentration for most SWCGs is around 3,200 ppm. If the salt level is too low, the SWCG will not produce enough chlorine. If the salt level is too high, the SWCG may overheat or malfunction.
- The pH of the water. The ideal pH range for a salt water pool is between 7.2 and 7.8. If the pH is too high, the chlorine will become less effective and more likely to evaporate. If the pH is too low, the chlorine will become more aggressive and damage the pool equipment and surfaces.
- The cyanuric acid (CYA) level of the water. CYA is a stabilizer that protects chlorine from being degraded by sunlight. The ideal CYA level for an outdoor salt water pool is between 70 and 80 ppm. If the CYA level is too low, the chlorine will be consumed quickly by the sun. If the CYA level is too high, the chlorine will be locked up and unable to sanitize the water.
- The temperature of the water. The warmer the water, the more chlorine demand it has. The colder the water, the less chlorine demand it has.
- The bather load of the pool. The more people use the pool, the more contaminants they introduce into the water, such as sweat, urine, cosmetics, sunscreen, etc. These contaminants consume chlorine and reduce its effectiveness.
How to Raise Free Chlorine Levels in a Salt Water Pool
If you notice that your free chlorine level is below 1 ppm, you need to take action to raise it as soon as possible. Low free chlorine levels can lead to cloudy water, algae growth, bad odors, eye irritation, and health risks. Here are some steps you can take to raise free chlorine levels in a saltwater pool:
- Test the salt level in your pool using a salt test kit or a digital salinity meter. If it is below 2,700 ppm or above 4,500 ppm, adjust it according to your SWCG manufacturer’s instructions. You can add more salt or dilute the water with fresh water until you reach the ideal range.
- Test the pH of your pool using a pH test kit or a digital pH meter. If it is above 7.8 or below 7.2, adjust it using muriatic acid or sodium bisulfate (dry acid) to lower it or sodium carbonate (soda ash) or sodium bicarbonate (baking soda) to raise it. Follow the dosage instructions on the product label and retest until you reach the ideal range.
- Test the CYA level of your pool using a CYA test kit or a digital CYA meter. If it is below 70 ppm or above 80 ppm, adjust it using cyanuric acid granules to raise it or partial water replacement to lower it. Follow the dosage instructions on the product label and retest until you reach the ideal range.
- Check the temperature of your pool using a thermometer. If it is above 86°F (30°C), consider lowering it by adding cold water, using a pool cover at night, or installing a pool cooler. Lowering the temperature will reduce chlorine demand and evaporation.
- Check the bather load of your pool and limit it if necessary. You can also ask your guests to shower before entering the pool, avoid using sunscreen or cosmetics in the pool, and use proper hygiene practices. Reducing the bather load will reduce chlorine consumption and contamination.
- Check the output setting of your SWCG and increase it if needed. Most SWCGs have a percentage setting that controls how much chlorine they produce. You can adjust this setting higher or lower depending on your free chlorine level and other factors. Refer to your SWCG manual for specific instructions on how to change this setting.
- Shock your pool with dichlor shock. Dichlor shock is a type of chlorine shock that is compatible with saltwater pools. It will help raise your free chlorine level quickly and kill any algae or bacteria in the water. Follow the dosage instructions on the product label and shock your pool at night or when the sun is not shining on the water. Do not use the pool until the free chlorine level drops below 5 ppm.