I'm sorry I don't have answers to many of your questions but I can say that I've tried many fleet enemas right out of the box and they always cause a lot of cramping for me and I can only hold them for a few minutes. However, I recently used hot water enema with apple cider vinegar in it and I was able to put double the amount I usually use and hold it for a really long time. Im guessing the warm water made the difference. our bodies are not room temperature, they are on average 98. 6 so probably something closer to that temp will be less harsh. Same with using an enema with salt. The blood In our bodies is isotonic with a certain concentration of electrolytes, including salt. Iv solutions that are typically used for hydration like .9noal saline and lacerated ringers are also isotonic.. If u use a different concentration of salt in your enema or no salt it will not work as comfortably and will cause fluid shifts in your intestines ( that may result in cramping). Just my thought but I'm not positive.