I just bought a KH kit and my water is very soft. When I add the first drop, it turns pale yellow, never blue. It's hard to tell that it is yellow but if I do as the instructions say and set it on a white piece of paper and look down from above, it is definitely yellow. pH is running about 6.6 in my 29 gallon and 6.2 to 6.4 in the 2.5 gallon. The pH in my tap water is 6.6. I have added quite a few plants (about 2 weeks ago) the 29 gallon in an attempt to battle cyanobacteria. It is definitely not growing like it was but still there. I would like to add CO2 as the plants aren't growing very well but afraid I will mess up my pH. I do a 5 gallon water change every week in the 29 gallon and a 2.5 quart change every week in the 2.5 gallon. All other parameters are fine: Ammonia, Nitrite = 0, Nitrate = 7.5. Should I also be testing for phosphate? I asked the guy at the LFS yesterday and he said he didn't think it was necessary, surprising since he had the test kits for sale. That was the first time I had been in that store but he said he had 7 tanks at home and sounded very knowledgable. I want to get my plants to grow and get rid of the cyano without harming or stressing the fish. Thanks in advance for any advice.
