Faucet Water Concentration PPM content and General Hydroponics (Maxi Gro) experience

Hey guys,
I am starting a new hydro grow (bubbleponics) and my faucet water concentration is 580ppm, when all the forums I have seen say it has to be 340. I was wondering do you have nay ideas about that do you think if I filter it the ppm count will drop?

Also I am going to use General Hydroponics (MaxiGro) anyone had any luck with it? Does it burn the plants in the suggested concentration because my ppm reads high.

Thanks for the help in advance.

My tap is really clean so IDK how this will affect it buuut my tap comes out at 75-80ish ph of about 9.2-9.5 and my cheap 15 dollar Britta filter drops it to 35-50 and the pH to 7.3ish

It's also like 4 months worth of water past its change date...QUIIIITE impressed.

Again, I'm not sure what is left or w/e but if you're on a budget, I don't see how you could go wrong. Plus, I have good water now =)