soil girls should be 6.5-7, i typically just feed with my tap water or 7.0 water. hydro (anything other than soil) 5.5-6.0. different strains in hydro like different ph's. i flush hydro with 5.5 water and typically feed with 5.8. this allows for a little room up or down for fluctuations and because the meters are only accurate to +/- 1 or maybe even 2 therefore it allows a little breathing room to keep it in the optimal range. i don't really worry about my soil too much. the microbial life in a good soil will naturally find a balance so long as you are not feeding them is an incredibly low or high ph. with experience you will learn the signs of an improper ph. generally they are wierd looking leaves. uneven growth on the leaves, curled up or down or twisted sideways. they will act fucking when its bad but if you have a good eye you can see even the slightest change.