I can't seem to keep a heater running for more than 12 mos. I have a 100gal tank in my office and have used a single 500w, dual 350w's, single 250w and 350w. In the last 3 1/2 yrs I have gone through 5 heaters. I have used Won Bros, Pro Heat, Jali, always the titanium, in sump, with and...