[OVT]

You can but expensive. Your TDS should be 0, with 0 GH, and more importantly, 0 kH and no minerals.
If you want to use it in your tank you will need to remineralize it.

 

[OVT]

Brita "pitcher" filters reduce copper, mercury, zinc, chlorine, cadmium, lead, asbestos, and benzene, as per their User Guide. Most of that stuff should not be in your tap to begin with. I cannot find any claims to lower pH.

 

[OVT]

No argument with any of the above. That is why we switched from Brita to Zero Water https://www.zerowater.com

My answer was: it's expensive and I have no idea how they lower pH. Maybe for a 10g? What is the throughput of those $50 systems?

There multiple alternatives for larger water volumes, none are that cheap or convinient.