Do not increase your ppm right now. You stated that ppm rises at the moment. This means she is drinking more water than nutrients, so you should be fine there.

I am assuming that you have had this ph problem from the beginning.
If that is the case, did you soak and adjust the ph of the Hydroton? (Took me three days of soaking and changing water to get it down and stabilized.)
If not this is most likely your cause of the rising ph. Hydroton comes with a high ph that should be adjusted down before use.