Red horemanii browning

Hi everyone,

My red Echinodorus horemanii plants have a problem in which the leaves are becoming brown and dying. It is more apparent in the outer, older leaves but new leaves are also beginning to develop round brown patches (photo attached).
Other plants in the tank (java ferns, bolbitis, mosses, blyxa, nana val, crypts, etc.) are doing fine.
Anyone familiar with the condition and its causes?

Tank specifications:
240 liters
Florabase substrate
108 watts of T5 flourecsents (app. 2 watts per gallon).
EI dosing at about half the recomended dose (KNO3 1/3 tsp 3 times per week, KH2PO4 1/8 tsp 3 times per week, Plantex CSM + B 1/8 tsp 3 times per week).
My water is hard.
Pressurised CO2 misting through an inline diffuser.
50% weekly WC.

Thanks a lot,

Matan.

 

Hi Tom,
Thanks for your reply.

Is it possible that my plants are lacking nutrients with my dosing regime?

I might have uprooted a bit around them lately so this might be the problem.

The tank is relatively new (1.5 months) and my tap water has not changed since I started it.
What do you mean when you say

I'm not altering the chemistry of the water other than the dosing I mentioned and CO2 injection.

What do you mean by

As you said, I'm very surprised to have issues with my swords of all plants since I have seen them thrive in all other conditions including low techs.
If anything, they seem to take over tanks rather than have growth problems!

Thanks again,

Matan.

 

Thanks a lot.

Matan.