DrBinocanswered grow question 5 years ago I don't let the water for my current outdoor grow sit and it seems to be doing just as well or better than my first grow where I usually did let it sit - but from the hose it's right around pH of 7 so I correct that down, especially if I am giving nutrients. This is anticdotal and I'm sure there's strains that may be more finicky so just try it and if you git issues go back to what was working?