With a pH like that though, I bet you have pretty high KH, so non-pressurized CO2 will be of questionable effectiveness.i have 2 male gbr's and i mix ro water with tap water to keep a ph of about 6.2. you'll have to find the correct portions of tap (treated) to ro, mine is 2/3 ro to 1/3 tap. just experiment until you get the right mixture. yes it's a bit of work but to me it's worth it. every fish has certain requirements that should be met if you want to keep that species of fish. i agree that you should try to give them a ph that they will thrive in. so many people say they will adjust to a high ph but all the literature tells you they like soft water with a ph of 5.5-6.5 not 8+.imo that's why so many gbr's die. yes the fish stores might be able to keep them for a few weeks in a high ph but it's an entirely different thing to keep them alive and thriving for months or years. my gbr's have grown from 1 1/2 inches to over 3 inches and have just blossomed with this ph. i have had them for 10 months. also it's important to do frequent water changes. i do one every 3rd day. it goes without saying that all your water parameters should be pristine. i test everyday with liquid tests. if you decide to go with the gbr's go with the lower ph. it will pay off i think. here's a good article to read and good luck.
