Grape. Watermelon likes grape.
Good call! My wife mixes modzilla titan with the watermelon stuff we use which is actually called "happy farmer" and was made by puff U.
That said, thank you all again for the advice. I am going to do it. It's going to cost a little more than I thought because I will be buying separate ingredients rather than the pre mix, so it will be a couple of weeks or so but I checked into it and for about $80 I can get all of the components, scale, supplies etc and should be able to yeild a little over 900ml of juice.