PH Levels??? What am I measuring

Guys so I am reading about PH levels and water and reverse osomosis

I have done dirt before but we used to fill a couple 5 gallon water bottles from the tap and let them sit a fert days that was it

I saw a couple guys chatting about getting a RO for tap water to feed the kids with

1st how do you get or treat your water before you feed the veggies?

2nd does it make sense to get something like this
http://www.lowes.com/lowes/lkn?action=productDetail&productId=129808-43353-WHER25&detail=&lpage=none ?

I am growing in a space around 3 x 3 x 3.6

and just feeding up to 6 at a time?

Your thoughts and experience

Thank you very much

If you have good soil it will take care of the ph for you. Letting your water sit out just get rid of chlorine, you still have probably atleast 300ppm of random shit. People get RO systems because it takes out chlorine/0 ppm/should balance ph. Ive used tap set out, straight tap, and RO, and they all work! If its just a small grow in soil, then i would stay with what your doing. Plus using RO will leave you calcium and magnesium deficient, so you have to make for that. I run an outdoor hydro setup off straight tap without being sat out, works as good as anything else.

i got a few plants that are in 5th week flowering stage and their doin allright i guess, the problem is im going outta town for one night and i usually turn lights on in evening. My question is will it hurt my plants if i dont light em up for one night ?