You don't have to worry about the pH changes due to CO2. It doesn't change the osmolarity of the water. It's the dissolved solids that are so hard for the fish to adjust to. So when you change the water they will do fine. Mine do and I have Amazonia and do 50% water changes all the time - including on my shrimp tank.anyone in the area raising or breeding german blue rams? i am a bit concerned with the water in arlington, 7.5ph...i will have ada amazonia in the tank so that should drop the ph. ill also have co2. the biggest worry is the water changes. the EI method of dosing calls for a 50% change at the end of each week. let say at the end of the week i have a ph of 6.8 (i dont know if this is accurate but i am guessing it could be because of the substrate im using and i hear co2 drops the ph but is that right?) and then i do a 50% and put in new water from the tap. wont that come out to 7.15 ph? wont that swing in ph be tough on the fish? any help is appreciated.