pH drop and low kh - How can I buffer my water?
I've got an aqueon evolve 8, so ~6 gallons of water. Until tonight, everything has been holding pretty steady, gh of ~100 ppm and kh of ~40 ppm as per the API test strip. I've had a pH of ~7.6-7.8 for the entire month I've been fishless cycling.
Yesterday I tested the pH and it was nearer 7.4, using the API liquid test. I checked it this morning and it looks to be somewhere below seven. It's a bit hard for me to tell the colors apart, but I would put it at 6.6.
Ammonia etc is at 0/0/20 (I let it go for a bit to feed the plants; I don't plan on letting nitrates get very high when I have a fish.) I dose excel daily, .5 ml, and flourish 3x a week, also .5 ml.
The tank is planted, obviously, and I have one nerite snail in there, so I know their respiration can contribute to a pH drop if my buffering ability is low.
So, I guess, the question is... how do I buffer? If I use crushed coral, will that make my pH skyrocket? Will I need to add baking soda to my water/in with my water changes? I've read a lot of conflicting information about buffers being good/bad, so someone who's got experience with it would be great. I don't want to subject my fish to unstable pH.