Don't boil your tap water. That outgasses all the precious oxygen!
Vinegar is not correct for pH down. You can use it to pre-condition hydro medium since that is just neutralizing exposed basic materials, but for your res, it is an unstable pH adjuster, like all organic acids. Organic acids each have a pH that they 'like' to buffer at. You need to adjust with an INORGANIC acid, preferably Phosphoric, which is the component of commercial pH down.

I control my pH with GH up and down, and I also use a nutrient that was designed to buffer in the range of the system type I run. I am in plain hydroponics and use a Canna hydroponic nutrient, Cann Aqua, and with my other nutes, it actually sets the pH right around 6-6.4 so VERY little adjustment is necessary. I do pre-condition my hydroton with distilled vinegar though because it's so darn cheap.

Good luck!