I wouldn't worry about your pH or KH, unless you are trying to keep fish that require harder water. If you keep fish such as tetras, angelfish, etc. that prefer soft water, or even fish that do fine in neutral water, they should be fine if acclimated correctly. As far as the plants are concerned, KH makes no difference. GH is the only thing that matters to plants, usually. pH is pretty much meaningless in and of itself, the concern should be hard or soft water and pH will fall where it may if you adjust those things to suit your fish, or better yet, choose your fish to suit your water.