Ph problem

So ive been growing my first time seriously and never got around to checking the Ph of my water i just used tap water but its around a 7.5 to 8 in pH so i was wondering what natural ways there are to lower it i cant seem to find anything on here or the internet on what to do

 

And that Ph down solution wont hurt the plants at all. Like ive read about that stuff but i figured itd be different if the plant is absorbing the solution rather than for a fish to live in it you know .

 

Thanks man good thing its only a few weeks into the grow well thanks i gess ill go purchase some of that ph down and some ph up incase if it ever goes to low