Hi all, I have water nipples in the bottom of a 2.5 gl bucket. I have seen some of you say you used fish tank heater to keep them from freezing. So I looked at them and bought this one http://www.amazon.com/gp/product/B006JVQ65M/ref=oh_details_o00_s00_i01 I got it and read in the directions that it should not be used in below freezing temps. Can someone be more specific as to which fish tank heater you use. Water was frozen this morning and need to get something hooked up. Thanks!