Join Date: Jan 2006
Location: Cherry Hill, NJ
Hmm. A decent set of pictures there, they certainly help.
Looking at the tips of the hygros they aren't getting smaller as fast as I'd have predicted, and the swords are showing damage along the edges of the leaves as well as the tips. This may also indicate a phosphorous deficiency.
Nitrogen deficiencies start in old growth and damage starts at the tips of old leaves progressing inwards towards the stem. When it becomes severe the growing tip quickly (within 2-5 leaf nodes) becomes smaller and stops growing.
Phosphorous deficiencies also start in the old growth and deterioration in leaves can start along the tips of leaves, but generally seem to appear more along the edges of leaves. The new growth keeps growing roughly the same size and does not grow progressively smaller.
I see several stem plants in your tank that have normal looking new growth. Even the Hygro has fairly large newer leaves, so it may not be nitrogen that is missing from the tank.
You can easily see if it is nitrogen though, just add a bit of KNO3 and if the plants dramatically improve within a week or two (lots of new healthy leave - old leaves stay the same). Then you'll know it was nitrogen. If that doesn't work, you'll have to add some phosphorous and see if plants improve.
Phosphorous deficiencies are quite rare in aquariums and usually don't show up if you have any fish at all. Flake food has a decent amount of phosphorous in it.
Are you sure that the stump remover you are using is actually KNO3? Some stump removers are made of other chemicals.