too low temperature?

Hey! I have my first brew sitting in primary in my fermentation chiller, and things have been going great! It is day five and airlock is still bubbling good. But, last night the temp in the chiller went down to 59F, and the strip thermometer read 64F on primary. I was just wondering if there is a temp. that would slow down or stop yeast? The recommended range for the white labs English ale yeast is 68F(i think). How low would you have to go to do any "damage" to fermentation? Thanks for the help!

It will just slow down the fermentation...and take longer...

Move it closer to your water heater.

Low temps will just make the yeast go dormant. Once temperature returns they'll wake back up. You didn't hurt anything, although you might have delayed things a little bit.