LOVE The rena heaters, i have them on all my tanks i love them soo much.
they're even better if you utilize them as intakes on your filters. but its not necessary.
i had lots of problems with stealths in the past, as well as elites, and the aqua clear was the worst. They were all positioned close to the intakes on the filters to maximize the amount of water flowing around them
went to rena and never looked back, they are expensive, but worth it. What you set them at is what they stay at within one degree, its not like other ones where they are 2-3 degrees different. my tanks are always within about .7 degrees to what they are supposed to be, no matter the temperature in the room.
i know it sounds cheezy, but these heaters are the best. in my opinion.