Reading true Amanos books and topics on this web, the PH value of 6,7 seems to be the case in almost every tank I come over. Im wondering why, since to me it seems just a tad to high with normal KH values of around 4. Also, for my fishes a lower value, aroung 6,5 or even lower would be more correct. So my question is, is there any good reason for keeping the PH at 6,7 or could it drop it to somewhere around 6 to 6,5 without problem?