Driftwood is one way but it does take a long time and it isn't very dramatic change and once you change the water most of those effects are lost. I have driftwood in all of my tanks. The best ways are going to be by using peat in your filter or in your tank or by the use of RO water. There are other ways to do it by using buffers such as discus buffer or acid buffer by Seachem but at this point I prefer the RO water. I use RO water for almost all of my Apisto's as I try to keep it below 6 normally right around 5.6-5.7. Also, depending on your filter you could put some peat in there as that will soften and lower the pH.