I have an extremely low KH level (1) in my new 30 gallon tank. There's no plants in it yet; just water, florite, and gravel. I lowered the PH from 8.0 to 6.0 with Seachem's Acid Buffer. This lowered my KH to 1 and raised my GH to 11. How do I get the KH back up, and is there a better way to lower my PH? (I want to keep Cardinal tetras in this setup.) Thanks in advance, Karen