What should i buy to purify my water?

[scherzo]

65ppm isn't bad.. I get 14ppm out of my tap.

I guess if you're really concerned then you may as well get the full RO/DI until.. I think J&L has one for $200 or so.

You could just get the Aquarium Pharma DI filter for about $60. It really depends on the size of your tank. With about 65ppm the filter will last you a while if your tank isn't big. And if you're patient.