Even if anything would work, since I am doind a biotope, I'd rather have the parameters be close to the biotope that I am replicating. Especially for the fish I may be including in the setup.
Right now the only planted freshwater biotope I can find with a high pH would be south african swamp. Which would be cool, except that it requires soft to medium water and my water is hard.
I think you should focus on what you want, not the tap water so much.
My tap has been very hard depending on where I lived, or very soft and few grades in between over the years. KH is the real issue, focus there, not pH, Gh can be higher or lower, just not limiting this is true for both fish and plants, focus on the KH as being the factor you look at, adding plants/CO2 etc modifies the pH, but does little to the KH.
pH in hardwater and soft water systems can and does move up to 2 full units of pH for hardwater marine systems and FW, and about 3-4 full units for soft water FW systems where plants are in abundance.
This occurs daily or 2x a day in tidepools.
So it would depends greatly on WHEN you took that pH measurement from this biotope and what the entire diurnal range for pH is and the alkalinity/KH.
Otherwise, such biotope info is of little use.
Biotopes where fish live are also heterogenous, they are not all the exact same habitat and perfect based on a few parameters taken at a particularly time of day, or season, or rain events, or year yo year, location(often pretty large regions, with different parameters in different pockets.......), plant status etc.........
I think people KNOW much much less than they realize concerning Biotopes.
But insist that the scant info they have is iron clad fact and the only way it might be there.
Do not fall for this.
Like farming and raising livestock, what is in nature does not imply what is best for your goal also. Do not get duped into Biotope pseudo science quackery. Replication is often not the best management solution, nor is it possible in most all cases. Can you get some elements? Sure. But not many.......the so called Biotope aquarium is more like any other planted tank that it is any real natural system.