Formerly sold as the KYK Harmony, Watershed AQ500 is one of the highest wattage machines on the market (Tyent's TURBO 7070 ) which often indicates a device's efficiency in creating ionized water. However in this case, the Harmony's plate size is not that impressive when compared to Enagic/Kangen and GoldFox products. Also, the plates in the KYK Harmony are "flat" surface. "Mesh" plates were adapted to increase surface area and electrolysis function. In the "Mesh" vs "Flat" plate debate, mesh plates tend to win out for their efficiency in creating ionized water where flat plates seem to have less issues with drainage and cleaning. In this case I can tell you from personal experience that this model operates very effectively at producing alkaline ionized water with a pH range from 4.0 to 10.0 - your results may vary based on your source water.The Watershed AQ500 also boasts ISO certification which is a standard of manufacturing business practices to ensure quality in production and manufacturer operations. ISO compliance does not guarantee compliance or necessarily product quality, but does certify that consistent business practices are employeed in manufacturing products. These consistencies typically (were designed to) result in uniform standards of production to ensure that most products are of equal quality.

What we like about the AQ500 is the SMPS power, the wide range of PH settings and the full 30-day money-back guarantee. Besides the greatly reduced risk of overheating, SMPS devices run more quietly and in some cases with lower power usage. The AQ500 has some of the greatest flexibility in PH settings of any water ionizer on the market, and who doesn't like a full 30 days to decide whether or not to keep the product or receive a refund (less shipping costs and 15% restocking fee). We also like the cost here. The Watershed AQ500 is the one of the more affordable water ionizers at $999 . If you're looking for a well certified machine favored by pioneers in water ionizer usage for health, the Watershed AQ500, formerly sold as the KYK Harmony, is an effective and affordable choice.

Another consideration, however, is the filtration system. The AQ500 is a single filter device and we hear a lot about preferences for dual filtration. The plus side to a single filtration device is maintenance. Typically the dual filters each have different lifecycles. This means that the first filter required changing in 6 months (for example) and the second 3 months later. That's double the maintenance, not to mention double the cost (at least, usually one filter is more expensive than the other - Tyent being the exception with both filters priced the same).

One last consideration again goes to the filtration system. Plan to replace your single filter about every 7,000 liters which will be 8 to 12 months depending on your usage. You can expect to pay between $59 and $89, depending on the grade of filter you choose (plus shipping) so factor that into your overall budget considerations. Did we mention that the AQ500 comes with multiple grades of filters to choose from?

Most people know I'm a fan of both the Watershed Products and the company's owner, Bob McCauley - author of "The Miraculous Properties of Ionized Water." Another ethical voice in the industry with respect for customers and distributors alike. You can feel confident that Watershed will stand behind their products and still be here when you're ready to trade up in 8 to 10 years.

• View the Watershed AQ500 Product Page