To many arial roots

Hi all
A question to all the plant gurus here.
My Rotala macranta is getting all over masses of roots but seems not to realy grow in hights.
The new leaves are deep reed but the plant looks stunted.
I have 4X 4500K 38W LFB and one 38W plant grow tube over 300 Litre.
The substrate is riversand on clay and i feed with bio CO2. Lights are on for 12h min and the tank is placed close to a window with 2Hours direct sun in winter and.
Any idea what could be the reason and what needs to be changed

 

R. Macrandra needs CO2 in abundance. Place it directly in front of your CO2 diffusor and you will see the difference. Also, needs high Ca and lower Mg. It therefore generally grows better for guys in Joburg as opposed to us on the coast with our soft water.

 

Thanks Laure, I was wondering why I had so many floating bushes.

I dont Use CO2 though, just Dirks Ferts's


Interestingly enough, once they have grown about 2-3 cm of roots, they break off and start floating. Must be their way of reproduction.

By the way,

Arial = Font
Aerial = in Sky
Ariel = Girls Name