if you're going this route, get organic. My advise, leave it like it is. Some apistos do like softer and more acidic water, but chances are they were bred in pretty close to neutral water and will live fine in it. The more finicky ones usually won't spawn in anything higher than 6, but will still live in it.
The more important thing than pH for apistos is stability, they can be sensitive. I tried the "make the pH right" trick for months. The only time they spawned were before I did this and after I stopped. The rest of the time they were in their "stress colors" (dark). Also, if you have cacatuoides, leave the water as that is even lower than they have in nature. Since some of the first apistos on the market came from soft and acidic water, it is a myth that all do. Cacatuoides come from a mineral rich hard water area from the Rio Ucayali in Ecuador, they do not soft water. Leave it like it is, 6.9 will be fine for any apisto to live in.
