Little tip for you: distilled water and RO water (if the membrane is new-ish) both have no buffering capacity; this means that the pH will swing wildly when you add something that is acidic or basic. Moreover, pH probes don't work well with pure water. pH papers are much better at that sort of thing; indicator solutions are also OK.
So, first off, I don't know of any fertilizer products that are designed to provide the "correct" pH (whatever that may be) right out of the bottle. They require adjustment- usually with alkali, because they tend to be slightly acidic in solution. Many products also have buffers added; it is immediately apparent which ones do because it takes substantially more pH up (alkali) to get the pH into the right range. The benefit is that these products tend to support the correct pH during growth. I note from personal experience that General Hydroponics Floranova takes about 4x as much potassium hydroxide solution (which is what I use for pH adjustment- I make my own) than comparable nutrient products that have no buffers added.
You can raise the pH with any one of a number of products; anything in the "pH Up" category at the hydro store will work. Baking soda will work in a pinch, but it adds no nutritional value; it is comprised of sodium (which plants generally cannot use), and bicarbonate (which is harmless). Other alkali, like sodium hydroxide (lye) and potassium hydroxide, are inexpensive and effective, but also extremely caustic (hazardous to eyes and skin) and (unless used with a buffer) will cause the pH to swing quickly. Make sure they are quite dilute before adding to solution; I use 0.1 molar, which works out to 5.61 grams potassium hydroxide into a liter of water. Note that such solutions should be stored in plastic, and not glass.
Potassium carbonate (used in many "pH up" formulations for hydroponics use) is much better, but harder to find.
