I'm sure you don't. But it's worth mentioning from time to time why water softeners (and API's "water softening pillow" which works exactly the same way and scandalously is flogged as an aid to keeping low TDS fish) are a Bad Thing.
I don't think the OP necessarily wants to replace the substrate or get their pH that high...
Same thing goes for distilled water which I used to use...luckily I didn't learn the hard way...
How about this stuff? It was recently reccomended to me to get PH down from very alkaline tapwater.
What stuff would that be?