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name that deficiency
Hi, I have an Amazon sword which I think is exhibiting a nutrient
The outer edges of the older leaves are turning chlorotic, then necrotic.
Soon after the plant kills off the leaf, and it melts. There are also small
necrosis patches on the rest of the leaf surface. The plant in general is
doing fine; it's producing new leaves, flowering happily, etc. I am seeing
similar symptoms in Sagittaria in the same tank; the Sag is also thriving
otherwise. A picture of an example leaf from the sword plant (apologies for
the color balance) is available at:
Tank conditions: shallow (10G) tank, and yes, I know it will grow out of
the tank eventually. 26W of compact fluorescent lighting. Temperature
72-74F. pH around 6.8 via yeast CO2 injection. I have not measured CO2
directly in a month or so so I will not give a reading. Substrate is
earthworm castings under sand. I add Dupla Drops at the rate of 1 drop per
day. Iron tests at 0.05-0.1ppm. Nitrate at 3-5ppm. Unknown, presumably
trace, nitrite and ammonia. Phosphorus tests nonzero but hard to measure,
below 0.1ppm. I keep KH at 3-4 via baking soda. I also add small amounts of
epsom salts at water change times (I've had Mg deficiency in the past).
>From the various deficiency charts, this would appear to be potassium
deficiency, but I'm dosing with KNO3 + KCl in 1:1 ratio until NO3 remains
at about 3-5ppm. Is K consumption that much higher than NO3?