This is definitely the issue, I think. It's only the anubias in direct light that are having this problem (which I moved into the shade today), and otherwise it's mainly the hygro. I assume that since hygro grows so fast, it has to quickly get carbon from somewhere so it cannibalizes it's own leaves to get it. Other plants aren't growing as fast as hygro so they are just stalling out until they adapt. I have my drop checker in the green now consistently so I'm hoping the problem will resolve itself soon. The new plants are sending out new growth all over the place, they seem just happy to have co2 now.