Update: The leaves on some of the plants continue to disintegrate, and today I saw that two of my anubias plants are having the same disintegration issue. Also I lost one dwarf gourami. I did a full battery of tests and couldn't find anything wrong, ammonia 0, nitrite 0, and nitrate had dropped from around 40 to below 5 in the past two days. Must be lots of uptake happening. pH is around 6.5 with the co2. I also cleaned out my co2 thing last night, it was a little clogged on one bottle slowing down the flow. This morning my drop checker still wasn't really in the green level though so I don't think co2 overdose is the issue with the gourami, although my co2 is now probably higher than it's ever been at this point. CO2 doesn't seem to have a lot of effect on anubias anyway....they've never shown any signs of anything before so this is mystifying. I did an immediate 50% water change today when I found the dead fish and redosed ei, lightly; and left off the calcium in case that was an issue with the fish dying (not sure what I'm dosing, just assuming it's calcium chloride)...but if it were I should be seeing issues in my other tanks too or with other fish. I don't know, I'm stumped.