So I've recently set-up a new tank and set in some plants within. My tap-water has a pH value of around 7.5 to 8. However, I've come to notice (using a pH drop test kit from API) that pH of my tank dropped to around 6 (that's as low as the kit allows me to see) after adding in some of my plant fertilizers such as Seachem's Flourish Advanced and Flourish. I had my suspicions, so I went and tested each individual plant suppliment that I use (after diluting them in some tap water) and found that most of them generally decrease the pH value of the tap water! Is this normal? And would this decreased pH effect in my tank affect the plants/livestocks within?