whats the secret to raising triops (aquasaurs)?

ok i have tried to hatch and raise aquasaurs (triops) i successfully hatched and raised 6 only for them to die, it says on all the sale websites of these all you need is a lamp over the tanks to keep the water raised between 70 to 80 degrees, which means leaving on all the time i suppose, i had a glass tank with a water heater in that you can get for tropical fish, as the lamp was not keeping the water a steady temaperature it would raise when heating was on in the house and drop over night. i used bottled water as suggested, on asking some aquatic centres they say they only live about a couple of weeks, others say up to 90 days. i have read these are easy to keep, it was hard work and quite expensive for heaters and water ect. i now have guppies in my fish tank by the way when i gave up but i would like to try again