My first big planted tank is coming along quite nicely but my plants are growing quite slowly, so I decided to set up my CO2 today. I ran a Red Sea CO2 test which gave a reading of 24 but have to be honest and say I don't really know if that's good or bad, so I started doing a bit of searching. I found this site and the handy little calculator which cofirms that the test was pretty accuate - my pH is 6.7 and KH 5. They seem to be saying I don't need any CO2 adding as it could be harmful to my fish. Is this right?? Thanks in advance for any advice!