Sounds like you're using an activated charcoal filter. That will be good for taking out chlorine, but if you want to remove minerals, you need an RO system or at least an ion-exchange filter.
Also, it's worth mentioning that the pH of the water isn't that important- the mineral content and grain bill will determine your mash pH which is the important pH to take.
I can't be arsed to keep up this list of what's in the fermenters, but hey, check out the cool brewery I own!
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