I've used the cheap ones you can buy from Walgreen's or CVS or a place like that. But be warned on the cheap ones, the plug needs to be exactly vertical (the normal way a plug is installed), if it's upside down, horizontal, or a power strip laying on the floor, the cheap ones won't work. The timer won't keep proper time, if it moves at all. (The digital one Derringer mentioned might be a better choice at those times) I did buy a decent timer/power strip from thatfishplace.com for my larger tank, it was well worth the investment if your running several things with a timer. It was about $30.