Tips to removing a metal stain
- Balance pool water chemistry before using any stain removal products. The water parameters should be as follows:
- pH: 7.2 to 7.6
- Alkalinity: 80 to 120 parts per million (ppm)
- Calcium hardness: 200 to 400 ppm
- Phosphate: Below 100 parts per billion (ppb)
- Before starting the stain removal process, a pulp-based filter aid is recommended in cartridge and sand filters. If a diatomaceous earth (DE) filter is being used, make sure it has been cleaned properly and recharged.
- Lower the chlorine level to (or below) 1 ppm. A high chlorine level or adding an oxidizer during the process can prevent the metals from being removed from the pool water, and the risk of re-staining is significantly raised.
- Add a quality stain removal product, and be sure to follow the manufacturer’s directions.
- After adding the stain removal product, brush the entire pool surface to ensure any metal particles that may still be clinging to the pool walls and floor will be displaced into solution.
- After brushing, add a quality sequestering agent. Be careful and aware that many of these types of products are phosphate-based, thus phosphate levels can increase during this process.
- Vacuum the entire pool thoroughly.
- After vacuuming, clean the filters thoroughly.
- Test and rebalance the pool water. It is a good idea to test the fill water at this time as well to determine if there are any trace amounts of metal in the source water. To prevent future staining, the weekly use of a non-phosphate sequestering agent is recommended.
- Do not super chlorinate or shock the pool for at least a week. As the chlorine will likely be low, it is best to bring the sanitizer level up slowly (e.g. 1 ppm per day for several days).
Testing and awareness
The key to the prevention and remedy of swimming pool and hot tub stains is testing and awareness. Be aware of the environmental factors of the pool and/or hot tub’s surroundings, as well as the quality of the fill water being used. It is also important to embrace and rely on more advanced testing methods that are now readily available—such as LSI—and know the details about the source water makeup.
Many metal issues are unknowingly created from tap water, and the necessary preventative measures are not taken. Last but not least, remember to brush the pool. The more the pool/hot tub is brushed, the less likely there will be any surface issues. By simply exercising a little more diligence and awareness, stains from metals and non-living organics can be easily avoided, allowing pool and hot tub surfaces to be better preserved.
Chris Marcano is the director of training and education for Natural Chemistry Inc., a manufacturer of pool and hot tub specialty chemicals in Norwalk, Conn., and Campbellford, Ont. Marcano has 16 years’ experience in the industry and is a Certified Pool/Spa Operator® (CPO®) instructor, and a member of the education committee for the National Plasterers Council (NPC). He is also active on the Association of Pool & Spa Professionals’ (APSP’s) board of regents and is a local APSP chapter president. He can be reached via e-mail at cmarcano@naturalchemistry.com.
