Hi all, further to a recent thread I started on here, I am now using 100% tap water which is pH 6.8 and TDS 450. However, my tank water is pH 8.1 in the morning and 7.8 in the evening when the CO2 is on. Now using up to 6 bps and still can't get a green drop checker or get the pH to drop. Have some dragon stone in the tank and unipac fiji sand which is supposed to be inert. So whats raising my pH. Any help appreciated.