Water PH & 1st Frost ?'s

Ill be chopping down my 1st grow soon. Im goin to switch back from Nutes to just regular tap water. In the beggining of the plants lives I was measuring the exact PH of the water, should I continue to monitor the PH or can I just give them tap water after it sits for 24 hours? Also, its starting to cool off in the N.E. region, I have alot of plants that will be ready anywhere from 1-3 weeks. Do I absolutely have to have my plants out of the ground BEFORE the 1st frost? Thanx.

i'm in the NE, no outside grow this year, but it was a nice summer for growing
i used to do outside grows quite a ways back(shit i sound old), and i always pulled before the 1st frost
i did that because i didn't know what i was doing back then, just didn't have the knowledge we have today
supposedly a light frost is not a big problem, double check, but i do see the long term weather forecast looks fairly good fro the next 2 weeks
best luck either way with your choice, some strains take more frost than others so do as much reading as you can