Yah, sadly thats the case with the API kit... But to know what you need to do, its best to spend a but of money on it. My KH is at a 14... (Really really really high) and my ph is 8.1... So there is no changing my PH. But for you, 7.8 is fine for a lot of soft water fish like bettas. There are a few on this forum who say my PH is very unhealthy but I get about 30-50 fry from my fish weekly so it cant be that bad.... If I were you I would not even bat an eye to your PH... But your ammonia needs to go to 0