synergy. An increase in the value of assets as a result of their combination. Expected synergy is the justification behind most business mergers. For example, General Motors purchased Electronic Data Systems in 1984 with the expectation that considerable synergy would result.
Filters can last from a few weeks to several years. In part, it depends on the materials they were made from, and their designed life span. As a general rule, most cartridge filters average 1 year. We recommend that you chemically clean your spa filters every 30 days to extend filter life. Not just spray them off with a hose, or rinse them off in the sink. A good Filter Cleaner & Degreaser will help remove oils and scum from the filter media.
The lifespan on a typical quality glass aquarium is about 10 years with regular use. It's not to say that it won't last 15 or more, but for my money its worth replacing after that period of time. I had an aquarium blow out when I was on vacation a few years back and that one was only 6 or 7 years old. I believe it was an AGA 22 gallon too.