I have one and it works good on smaller tanks. The dumb fan on it has to fun 24/7.
I second what sayurasem is saying, DIY a fan or just buy one from fleabay. I had a double fan on my 48 gallon and it was keeping the temps another 8 degrees cooler than ambient, they really do work good.
Forgot to mention another tip, switch your photoperiod to night time. I realize the biggest heat source on my tank is my light. So if the tank is not in your room/ your okay with the lights on at night, that's another way to keep tank temperature stable and keep it low.