I hit the pH issue when I moved to Burrum Heads. Wonderful place if you want African cichlids with high pH. Out of the tap its over 8.
I keep plecos who in their previous address lived in pure rainwater with buffers up, not down.
I have multiple tanks but initially as each couple of tanks came up I had to use pH down. There are varying qualities of this I found. Stand alone tanks I had to add a bit, add a bit more over days until it settled.
I had driftwood, blackwater, almond leaves and peat and used pH down. It was annoying how the next day the pH would spring back up.
I got the tanks to where they were sitting steady on a ph of about 7.4 down from 8.2. Best I was going to get without wiping out the kH and causing a pH crash.
Once all the tanks were up and the ibc filled for water changes I was able to treat just the ibc not the tanks. I fill the ibc days before water changes are due and aerate it. That alone drops the pH a little bit to 7.6. I also got some long tubes and run a little Eheim 2213 on the ibc with a big bag of Macropore Gold in it. This converts some of the town water nasties into stuff more suited for fw fish.
When its water change day, I add a dollop of Easylife to the ibc as well as one of blackwater and a little bit of pH down. I use a bit less than a 20ml medicine glass of the pH down and dissolve it to the stored water of a little less than 1000trs. That will initially drop the pH to 6.2 or so. Leave it an hour or two and the water is good to go for all the tanks water changing. If I leave it too long standing the pH will start to rise so I need to get it in the fish tanks that day. It doesn't rise much once its in the tanks.
Over the week the tanks pH's have snuck up a little to 7.2 or so despite driftwood so that water change will drop the pH in the tank but only to about 7 or so. I have monitored it before and after so its not a big swing for my fish.
Note, different waters have all different properties and tds levels so you just have to check yours yourself. My kH is about 4 in pure town water and gH is an odd 6 which I would have thought would be higher but it isn't so that's a good thing. Adding the pH down will push the tds up a bit but for me its not a real issue as I have a low gH to start with.
Fiddle with your water change water rather than the tank water all the time and see how it goes.