KS advised against using super pure water.. like RO, DI is totally stripped of buffering minerals, some of which are good in there to help keep pH more stable,.... mix it with some tap water that's had a chance to dechlorinate (gas off),... well, that is if it's not being treated with chloramine, which wont gas off,..might need to check with your local water Co. on that to be sure,....otherwise, no need to pH RO/DI here... thing is, w/o those buffering minerals, mostly CaCO3, pH will swing wildly with small inputs and be way unstable,...