This question popped in my mind and I have never seen it brought anywhere else before. Where is the best source for water in a hydro system? Should you use tap water, by distilled water from Wal MArt at $0.57 each? can you use the filtered water from your refrigertor dispenser? Or do you buy a brita type water pitcher filter? Or does it really matter where you get your water from. Me, I used to think buying gallons of distilled was the way to go, but am now contemplating something different.
I live in the sticks and i use straight well water for everything, it is cleaner than the water comapnies "pure" test water and is basicly neutral, if your loking for an alternative try some well water, if you cant find any buy a brita, it will pay for itself over time
I'm no hydro grower but I think I would just use tap water and leave it sit out overnight, maybe buy some pH Down, and find remedy for hard water and a decent ppm.