well you can also have a shift in ph up naturally if you are using tap water, lots of variables.
Are you using tap, or RO?

For instance my starting tap water ec is .4 when using RO water its .0
I personally go by ec, as ec is universal, where as ppm changes depending on who manufatures it, for instance I believe blue labs 1.0 ec equals 700ppm
But on a hanna its 1.0 equals 500ppms.

:wtf: