Yep all because of too much co2
The second 2 pics are about 3 weeks earlier
Ph 5.9 in first pics and ph 6.1 in last pics, nothing else has changed
Livestock and plants are probably the most accurate drop checkers we have
Plants melt and get algae with low co2 and fish show changes in behaviour and appearance when it is too high. different fish are affected differently at different times, some symptoms appear long before any deaths occur and in my tank all this happens in the time it takes my drop checker to change from green to yellow
Its like having lots more colours