7.5 ph is high. but definately dont lower your ph to 5.5 - 6.0 unless you are using hydro! if you are in soil 6.2 - 6.8 is preferable. Also i would flush with a good ph if soil 6.5 flush until soil drainage reads close to the 6.5 level. and if hydro do a rez change and use 5.5 ph for the water in the rez. after ph is right things will look better if you were to treat any deficency now you would just make things worse.