A pH of 10.0 for tap water seems extremely high. I can't tell you what is in your tap water because it will vary everywhere. Your local water municipality may be able to shed some light on that for you. But assuming using a better water quality, even from an inexpensive charcoal filter or water from the $0.25 a gallon machines at the market (even for just a short period of time to see if it helps). Then tap is what you have to work with. There could be contaminates in the water that could affect the pH. I don't know how much chlorine might affect the pH, but you can let the water sit in an open container (with lots of water surface area) for 2 to 3 days and let the chlorine dissipate to see if that helps if there is a lot of it.
I don't know if you are using a pH test kit for hydroponics or not, but that would be my first recommendation. I use the pH drops from General Hydroponics, they only cost 7-8 bucks. Also I would use pH adjusters designed for hydroponics, anything else is likely to be quite unstable, and the more you need to add wont be good for your
nutrient solution. I use the dry pH adjusting crystals from Earth Juice myself. They only cost about $9 (each up/down) for a one pound container, and they have lasted me over a year now. Adding bubbles to the nutrient solution wont change the pH. Your tap water itself does not have any buffers in it, that will be in the
nutrients and pH adjusters (designed for hydroponics) to help stabilize the pH level.