Planted Tank Obsessed
Join Date: Feb 2004
Location: Westchester County, NY
For yellowing leaves consider that the iron level may be deficient. But, that may just be one problem among many since your plants may not be getting enough of a number of elements that they need, from CO2, to nitrates, as already mentioned...work on the CO2, and think about dosing ferts like James suggests...your lighting is way higher than the other elements of photosythesis that are available in your tank so if you want to keep your lighting where it is it's essential that you spruce up those other things.