Add anything thats acidic. Vinegar works great, or concentrated lime juice in the small neon green plastic bottles from the grocery store used for making mixed drinks:] fresh lemons.. fresh limes.. etc.
you didnt mention if you added any nutes as that will usually raise your ph. in any case adjust your water lower than 6.5 until your soil runoff is arpund 6.5-6.8. what kind of soil are you using? rich soil can accomplish both of your issues.