lowering ph

I will try to keep this simple....First, I know my main problem is very high KH, which also means very high PH. We have had aquariums in the past with much less trouble. But my uncle decided about a month ago, I think, to start a new one, which I am left to care for, as he works out of state...

Hello I am worried pH of 7.8 is too high for my 30 gallon aquarium with 5 zebra danios, 6 peppered corydoras catfish, 12 neon tetras, and nerite, trumpet and ramshorn snails. I tested my tap and found that it is 7.8 as well. I tried using distilled water mixed with tap during 30% water changes...