I do not think age is a good indicator of the conditions of the tank. There are too many chemical formulas, organic silicon, the surface preparation prior to the application of silicon is very important. After appropriate treatment of high-quality silicon surface has operated within its specifications may live longer than people old enough to read them.

Most are flexible, very long time, but in the end that move them, and if the do, to stress the seals, causing leakage only sold a 30 gallon tank and the little guy at one of its advantages! I said to hold unit And evenly frame, and he would not listen.I'm curious myself - I have a used 75 - people forget that there are some areas near broken glass seals