My seven year old 300 watt Eheim Jaegers are slowly dying. Thinking about replacing them with another set or Finnex titaniums. What wattage would be comparable in the Finnex heaters? They aren't rated for as large a volume as the Eheim's presumably because they are smaller. I would run two. My system volume is 200g. My Jaegers ran for about seven years, how long would titaniums last?