Iron decencies? How long before you should see the results of dosing

[Minu]

Good new first. Gone are the days of 0 Nitrogen, high phosphorus with stunted growth & brown Alge. Things are growing much better.  

"Bad news" pretty sure my plants are lacking in Iron. (all stem plants). Rotola looks OK, but the Wysteria leaves are super lime green and so thin they nearly translucent. 

I've dosed Flourish Iron 4 times in 10 days and see no difference except the Rotola is more pink/red. 

Questions: 
Am I on the right track or could it be something else? 
If on the right track will the existing leaves improve, or just the new growth and how long before I actually see it improve?
I noticed the plants ate the hell out of Nitrogen until they finally 'caught up" now they are not using it as quickly. Is it the same with Iron or other deficiencies?   


 

Edited August 19 by Minu

[Seattle_Aquarist]

Hi @Minu,

Correcting any nutrient deficiency will seldom improve any of the existing leaves on a plant.  Why?  Because the deficiency symptoms occurred when the leaves were  formed.  Sometimes with mobile nutrients (N, P, K, Mg, etc)  you may see some slight improvement in existing leaves if the deficiency is corrected however with immobile nutrients (Ca, Fe, S, B, etc) there will likely be no improvement in leaves that were formed when the nutrient deficiency was occurring.  To know is you have corrected a deficiency watch the new leaves as they are formed and mature (which might take a month or more with slow growing species).  If the new leaves form and mature normally and look healthy then the deficiency has been resolved.  -Roy