What kind of medium are you in?
When you say ph is 7 is that your runoff ph or the input water?
If you are in any kind of amended soil or anything with slow release fertilizer you will not need to feed for the first month or more normally.
A ph of 7 is neutral. These plants like slightly acidic I water around a ph of 6 but not too picky on it and my plant will get anything from 5.7 to 6.5.
Also if running purified water be sure to add cal mag… and be sure that is the first thing to go into your water and mix well.