Here's what I do.

Punch one ~1/8 inch hole in top and one or two in the bottom of a set of bleach bottles and string them out over my pool. I use one bleach bottle for every day I will be gone.

http://www.jreece.com/bleach1.jpg
http://www.jreece.com/bleach2.jpg

The density of bleach is 1.09 (slightly heavier than water) so it slowly leaches out of the bottles. My experience is that it takes 5-7 days to totally get out of the bottle with 1/8 inch holes. I also run my pool pump using a timer.