hello /algal scrubbers

Hi, everyone. I'm a new addition to the list so I wanted to say hello. I've 
been keeping planted tanks for about 3 years now. I try to keep things as 
low-tech as possible, just trying to keep things in balance.
I've been thinking about building an algae scrubber, hoping that it would help 
with the small algae problems that I have from time to time. Does anyone have 
any info on how well they work on planted tanks, or info on building one?