Help to identify deficiency

[mattski]

I'm having trouble with some of my plants, namely the anacharis and pink iris. They are getting new growth, but after a few days, those leaves die off, turning brown first, then breaking down. I am having trouble identifying the deficiency, but from what i'm reading, its probably a lack of iron, calcium or copper. Am i correct?

I'm currently using some Aussie liquid fert, AquaMaster PlantFood which contains P, N, K, Chelates of Iron, Copper, Manganese, Boron and Zinc. Should I up my dosages of this? I am also considering buying some Flourish Excel. I've heard that is pretty good stuff.

 

[Silly me]

your lighs over the tank? Most red/pink plant needs more than normal lights..
What is the size of your tank and the amount and type of lights do you have..