Originally Posted by rameshg
I trimmed the yellowed leaves a couple of days ago, when I buried the Osmocote capsules. I shall post photos if the problem comes-up again. Another thought is the amazon sword which showed more yellow and it's been in the tank for about 506 wks. May be it's still getting used the plant? I would understand that might be if old leaves yellow, but there are some young ones too...
The older leaves that were on the plant when acquired will often die off over a few weeks. It is the new growth emerging from the centre of the crown that is key. If this appears green (may be pale green or darker, depending upon nutrients) and remains so, then all is probably fine. But if these new leaves begin yellowing or getting brown patches or holes or turning whitish with dark green veins--all these are symptoms of nutrient deficiences (or sometimes excess of some nutrient which causes deficiency of another).