The Edge - Quarter 4, 2008 - (Page 26)

that the manufacturer is doing more than just matching a dose with a flowrate. You can even go so far as to ask them to send you their calculations for how their dose was determined. Don’t worry about the fact that you may not have a clue as to how to read it. If the response is: “That’s proprietary information,” be suspicious. We’ll go through a short list of criterion that will help you make your choice. Some of these overlap with each other, but it will all come full circle. Required Dose: This depends on what you are trying to achieve. Two standard doses often used are 40mj and 60mj. A Fluence dose of 40mj ensures a 4-log reduction (99.99% inactivation of pathogenic bacteria and viruses). This would be the recommended dose for many outdoor and some indoor applications given that the rest of the criteria is understood. This dose will also reduce chloramines if the proper recirculation parameters are met. A Fluence dose of 60mj would have the same germicidal attributes as the 40mj dose, while having the added benefit of reducing chloramines in systems with slower recirculation rates and/or indoor applications where improving air quality is necessary. Type of pool/number of bathing guests: The following questions must be answered when choosing a proper UV system. The amount of people using the pool and what use the pool provides all affect the amount of sanitation needed. Is this for indoor or outdoor use? Is it a spa, wading, exercise or kiddie pool? Is this a residential pool with minimal bathers, or do the homeowners entertain often with large gatherings? Volume of pool/turnover period: This is a crucial component that somehow is seldom asked, yet is a vital aspect that ties in the above criteria. Many know that it’s necessary to provide the flow, typically in gallons per minute when specifying a UV system. This only paints a partial picture. Take, for example, a flow of 100 gpm. I have seen this flow used for large spas with a recirculation rate of 30 minutes, to small indoor commercial pools with a four-hour recirculation rate, to a large outdoor residential pool with a recirculation rate of eight hours. All of these applications vary greatly in the other criterion already mentioned, i.e., dose, type of pool and number of bather guests. To recommend a UV system based solely on the flow is negligent and can be costly. If a system is undersized, there’s the obvious risk that disinfection and reduction of chloramines are not occurring. If a system is oversized, then there’s the unnecessary equipment expense associated with that. UV-Transmittance: %UVT (Percent of UV Transmittance) is the percentage of UV light that can penetrate through 1cm of water. This is a vital factor used in the flow rate calculation and is probably the most crucial yet overlooked parameter by many substandard UV equipment manufacturers. Some of the factors that effect UVT are dissolved solids in the form of minerals or suspended solids such as debris from trees and leaves as well as suntan oils from the bather load. As a general rule of thumb, 90 percent is often used as the accepted transmittance for pool and spa applications. Keep in mind that this is simply a rule How About You? Produce your custom label on silk screened, color-coded bottles and pails. We use the highest quality products and accept very reasonable minimum quantity orders. Same day shipping. Point of Sale Inventory Control Customer Relationship Management Internal Communication Control in the Ofﬁce Pittsburgh Sales Ofﬁce Scheduling Service Construction + Much More! 866.224.7225 “We Know the Pool & Spa Business.” Visit our website to request FREE info and an online demo! 26 www.nespapool.org ® #1 in Private Labeling www.rbcontrolsystems.com 800-523-6533 http://www.rbcontrolsystems.com http://www.njonas.com http://www.nespapool.org

Table of Contents Feed for the Digital Edition of The Edge - Quarter 4, 2008

The Edge - Quarter 4, 2008 Contents The President’s Message New Pool/Spa Federal Safety Act Worried About the 2009 Market? Treating Hot Water? Project Focus The 411 on UV Disinfection for Pools and Spas The Advantages of Seeding Aggregate Surfaces Pool and Spa Industry Wins Gold Choosing a Retirement Plan To Get Best Coverage at Lowest Cost - Shop Now Index of Advertisers

The Edge - Quarter 4, 2008

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