So, does anyone have a favorite type, brand water heater to put in a small water tub? I have heated water buckets for their stalls; but, I would really like to have a heater to put in the tub that I have outside. The local shop has one; but, it was 1500W and the husband wasn't going for that. I did find one online and almost ordered it; but, wasn't sure if it would do the job. This is the one I was looking at in a 500W...http://www.pet-dog-cat-supply-store.com/shop/index.php?page=shop-flypage-24601. Any thoughts?