Closing time: Techniques for ‘hard’ or ‘soft’ winter pool shutdowns

The correct sequence for chemical adjustments

Time should be allowed when winterizing a pool and preparing the water for closure. Chemicals should not be added all at once and never mixed together to save time. The following is a handy list for service techs in regard to the proper sequence for adding chemicals:

1. Chelating or sequestering agents (preferably EDTA or non-phosphate products)
2. Alkalinity adjusters
3. pH adjusters
4. Calcium hardness increasers
5. Chlorine compounds
6. Water clarifiers and enzymes
7. Algaecides
8. Cyanuric acid
9. Phosphate removers

The Langelier Saturation Index explained

The LSI is a method for determining the concentration of calcium in pool water. It is used to establish the potential for water to be either scale forming or corrosive. Since temperature plays a role in balanced LSI, it is vital the pool LSI remains as close to perfect as possible.

Cold temperatures can lead to corrosion and as the water begins to be heat up, it can start to precipitate calcium as scale. There are many tools available for service techs to calculate the proper LSI. In fact, most test kit manufacturers include LSI information in the kits. Also, there are now several smartphone apps available to help determine and adjust LSI.

Target ranges for water chemistry

Robert W. Lowry is an authority on water chemistry and has more than 45 years of experience in the pool industry. He recommends setting ideal targets for water chemistry adjustments rather than settling for just the minimum or maximum levels. In his book Pool Chemistry for Service Pros 2018, Lowry points out if water balance levels are all at the minimum acceptable ranges, the water is going to be corrosive. Conversely, water balance that is at the maximum level will be scale forming. That said, he recommends the following ideal target levels to achieve perfectly balanced water:

• pH: 7.5
• Total alkalinity: 90 ppm
• Calcium hardness: 350 ppm for plaster pools and 250 ppm for vinyl pools
• Total dissolved solids: no more than 2000 ppm over startup. If the water in the pool is 2000 ppm over what the source water is, TDS from the pool should be tested, and then from the tap, and compare the two.
• Cyanuric acid: 50 ppm

Terry Arko is a product training consultant at HASA Pool Inc., a manufacturer and distributor of pool and spa water treatment products in Saugus, Calif. He has more than 40 years’ experience in the pool and spa/hot tub industry, working in service, repair, retail sales, chemical manufacturing, technical service, commercial sales, and product development. He has written more than 100 published articles on water chemistry and has been an instructor of water chemistry courses for more than 25 years. Arko serves as an observer on the board of the Recreational Water Quality Committee (RWQC) and is a member of the Council for the Model Aquatic Health Code (CMAHC). He is a Commercial Pool Operator (CPO) course instructor, a teacher of the Pool Chemistry Certified Residential course for the Pool Chemistry Training Institute (PCTI), and a member of Pool & Spa Marketing’s Editorial Advisory Committee. Arko can be reached via e-mail at h2owrite@gmail.com.

References:

• Association of Pool and Spa Professionals (APSP) Service Tech Manual 4^th Edition 2010-2013.
• National Swimming Pool Foundation (NSPF) Pool & Spa Operator Handbook 2017.
• The Complete Swimming Pool Reference, Tom Griffiths, Mosby Inc., 1994.
• Pool Chemistry for Service Pros by Robert W. Lowry, Lowry Consulting Group LLC ©2018.
• Certified Pool-Spa Operator Course Supplemental Information, Leslie’s Swimming Pool Supplies 2017.