Hi Guys
Yesterday I checked my waters tds level and It had climbed to 007 tds, however I am fine with this and will work with it at this level, But today I have just checked it and over night its risen to 126 tds?
its the second bag of resin in 2 months, my water going in at 357 tds, could there be something wrong with my di vessel or is it just because my water is so hard? Not a good morning for me here 
Your water is way too hard for di only Mark, but you have not said how long it is lasting?. I used to be di only, but the water i used at the time (at my parents), was about 55ppm. I would get 3.5-4 weeks out of a vessel (i think my vessel is about 10l, but not sure). When my resin started to go off, it usually did so gradually, but i would think at 357ppm that would not be the case!. Also, i dont see how your tds could have risen overnight, surely it must have already been at 126 when you stopped yesterday?.