Algae
The other element of seasonal pool maintenance has to do with what grows in the water. Mould, algae, bacteria, viruses, and other micro-organisms all linger in the pool regardless of the season. However, as the water temperature decreases, the activity of these issues also declines—sometimes exponentially. Just like when the pool is open, there is equal importance to eliminating water quality issues—or at least keeping them under control—while the pool is closed.
Using a product to keep algae growth under control is universal in the approach to off-season care. This is regardless if the homeowner covers the pool or leaves it exposed to the elements during the pool’s inactivity. That said, there are essentially three types of algaecides to consider.
Algaecide can utilize quaternary ammonium compounds (also often referred to as quat algaecides). They are inexpensive and have the potential of ridding the pool of existing algae. However, these algaecides, especially at higher concentrations, may cause foaming. Further, when chlorine is administered in the water at high levels, the effectiveness of quat-based algaecides is diminished.
Other algaecides include those that contain poly dimethyliminio ethanediyl dichloride. These algaecides are usually referred to as poly algaecides. They are non-foaming and offer greater staying power in the water in the presence
of chlorine.
Lastly, algaecides with the presence of copper are effective chemistries to combat algae in the long-term. These types of algae inhibitors are like poly algaecides as they are typically non-foaming and hold well in the water even in the presence of chlorine. Though these are the three basic types of algaecides used in pool winterization, there are plenty other variations/hybrids of these algaecides. Poly and copper hybrid algaecides are a growing market segment because they offer the advantages of two separate algaecides in a single container.
Shocking
When service techs close pools, shocking the water is a must to reduce the number of contaminants in the pool. After the water is shocked, contaminant loads are reduced which frees disinfectant (sanitizer) to help control the other materials lingering in the water—either currently or those introduced during the off-season. In this case, some service techs prefer to use chlorinated products, while others like to use non-chlorine oxidizing shocks.
There are advantages to using chlorinating products when closing a pool. For instance, if chlorine levels are non-existent, then applying a chlorinating shock will simultaneously scourer the pool of algae, bacteria, and other contaminants, while leaving a residual sanitizer for the period the pool is closed. When stabilized chlorines are used, the impact to the pH is also minimized.
Non-chlorine oxidizing shocks, relative to chlorine, is still an up and comer in the recreational water maintenance industry. Since most service professionals are comfortable with chlorine, many do not look at non-chlorine products as an effective tool—especially when it comes to winterizing. However, just because the product does not have chlorine present, it does not mean it is any less of an oxidizer. Non-chlorine oxidizers can scour more contaminants in the water than chlorine and, since it does not contain any chlorine itself, it will not form with chlorine to create any disinfection byproducts. Most importantly, its lack of chlorine is better for the long-term appearance of the pool’s surface. Regardless of its effectiveness as an oxidizer, a chlorine presence during the off-season is still a must.
Additional treatments
Depending on where the pool is located (in terms of geography), the quantity of products and the frequency of their application as part of a pool winterization program may vary. In Canada and the northern United States, service techs typically treat the pool once, as a cover is placed on the pool, which prevents outside debris and waste materials from falling into to the water. For those who do place covers on pools and experience mid-winter thaws, or those who have mesh-covers, additional algaecide treatments are important to keep growth under control.
In southern and southern-coastal communities, a cover is not typically placed on the pool. The lack of a cover means the pool water is exposed to outside debris and, of course, the sun. Due to the pool’s exposure to the elements, the water needs to be treated more often than a pool located in the north, but greatly less than in-season due to the colder weather.
