Vinyl Liner Thickness: Gauge versus MIL

The purpose of this article is to clear up the common confusion when comparing MIL thickness to gauge when discussing vinyl liner material.

It is important to note first and foremost that “GAUGE” has no meaning in the plastics field. Gauge is a unit of measurement without a specific distance; this is dependent on what you are measuring. For example, a 12 gauge shotgun barrel is different than a 12 gauge wire but in both cases the higher number is a smaller unit.

Sheet metal is commonly specified by a traditional, non linear measure known as it’s “gauge”. The larger the gauge number, the thinner the metal. The same is true for electrical wire gauge, the larger the gauge measurement the smaller the size of the wire.

The definition of MIL is the UNIT OF LENGTH EQUAL TO 1/1000 INCH USED ESPECIALLY IN MEASURING THICKNESS (AS PLASTIC FILMS). MIL is a North 

American measurement (imperial measurement) that is equal to 1/1000^th of an inch in thickness.

MIL measurements have nothing to do with the metric measurement millimeter. Due to the way that these measurements are acquired, 27 MIL vinyl is thicker than 20 MIL vinyl but 20 gauge or 20G Vinyl is a meaningless term without measure.

While the term gauge is not a “real” term it is unavoidable within the pool industry due to internet marketing and the need for pool liner manufacturers to follow suit to market their product.

At 21^st Century Pools & Spas our stock aboveground liners are 17 MIL standard and hold a 20 or 25 year warranty depending on the brand of liner that is chosen. It is important to ask all retailers, online or otherwise, what their liner MIL thickness is as that is the only real measurement for vinyl liners. It is also useful to ask for warranty information to ensure your investment is adequately covered.

How Do I Maintain Proper Water Chemistry?

Maintaining clear water in a swimming pool may seem like a daunting task at first,  however, it can be made easy and stress free by following a once-a-week, 3 step chemical system. 

The 3 step system that we follow at 21^st Century Pools and Spas includes sanitizer to keep the water clean, shock to remove contaminants in the water, and algaecide to both kill and prevent algae.  

The 3 step system works in both inground and aboveground pools, of any surface type, that have water circulating through the pump and filter for 10-12 hours per day.   

Step 1 – Sanitizer 

• Sanitizing the water with a chlorine tablet is the primary method of keeping pool water clean.
• Chlorine tablets may be placed directly into the skimmer basket, or in a chlorine floater that moves around the pool. 
• Be sure that if you are using chlorine tablets that the pump runs for at least 10-12 hours every day.  Chlorine tablets continue to dissolve even if the pump is not running and sitting chlorine can potentially bleach the liner of your pool.
• Chlorine tablets that contain stabilizer (CYA) are formulated to last longer than regular chlorine tablets when exposed to the sun.
• Some chlorine sticks are formulated with a special film that covers them when the pump and filter are not running to prevent chlorine from pooling in high concentrations and staining the liner.  If your pump and filter do not run constantly, consider switching to chlorine sticks with this coating.

Step 2 – Shock 

• Shock works along with the sanitizer to destroy bacteria and other contaminants.
• Shocking a pool once per week eliminates the contaminants that the sanitizer collected throughout the week and rejuvenates the chlorine to allow it to continue cleaning the water    
• Some shocks contain algaecide and water clarifiers that contribute to maintaining water clarity.
• Make sure that you read the instructions on the shock that you are using.  Some shocks must be predissolved and others require waiting after shocking before swimming.  In order to keep your pool surfaces looking good, and your swimmers safe, you should make sure to understand how to properly use all pool chemicals.
• Be sure to remove the cover of the pool before shocking and keep it open for a few hours after shocking.  The chemicals in shock are very strong and can break down the solar cover material.

Step 3 – Algaecide 

• Algaecide can work as both an algae killer, and an algae preventative.
• It is important to remember that shock may halt algae growth, but algaecide is the product that actually kills and breaks down the algae spores.  
• The most effective algae killing treatments include both shock and algaecide within an hour of one another, to first stun the algae and prevent continuing growth, and then to kill the visible algae and any remaining spores.

In order to make sure that the levels in your pool are within acceptable ranges, you should test the water once a week with test strips, or bring a sample of pool water to a professional pool company for a comprehensive water analysis. 

pH, alkalinity and calcium hardness levels must also be balanced on an as needed basis.  These levels will change with rain, water addition or loss and with heavy swimmer loads.  Levels should be checked after each of these events in order to maintain steady chemical levels.

Be sure to ask your local pool expert about chemical interactions and proper chemical doses for your particular pool.