So to test the theory that CO2 is the issue in my 4ft 250lt I removed the fish and shrimp and whacked the CO2 right up, to well over the fish death level (I unfortunately left two oto's in there, which were in a shocking state when I found them and probably wont have survived much longer, but think they just about pulled through ) and have been dosing 10ml excel everyday and EI (40ml TNP for trace). I had to change the FE this morning, which means I've pumped a 2kg FE of CO2 into it in two weeks, that should have been enough surely? Here's the result (wait for it!) Exactly, nothing has changed, zero, nada, zilch. The leaves are still dieing very quickly, with slow overall plant growth. I know two weeks isn't very long but lets be honest, there should have been at least some change in that time if CO2 had been the limited/controlling factor. Anyone brave enough to try and explain this? Sam PS - I've now reduced the light to 1x54w, if nothing else I should be able to have a low light tank, crikey I've spent enough, I want something planted!