Exactly! lol
I would agree with everyone else though. Just bump up your chlorine level before your trip. With sufficient chlorine levels (AND STABILIZER), the chlorine residual will last a week or more before algae starts to grow.
You may also consider a preventative algaecide. There are some that lasts 3 months and will prevent algae from growing when there is insufficient chlorine levels.

A few jugs of bleach will allow you quick correction in the event that you do have a problem when you return.