I am wanting to change my watering system to a lidded bucket with the nipples. I have been looking at nipples and am not sure which ones I need to order and which ones are best. I have seen push in and screw in types. I am planning on using an old cat litter bucket and a home depot bucket. Also, I was considering using an aquarium heater to keep the water from freezing in the winter...will this be sufficient or should I consider something else? Thanks in advance for all the help/suggestions you may have.