Elodea Densa Or Crispa

[Abyss]

Hi,
 
I want some floating plants for my Gulper Catfish Aquarium. Keep the light off the big catfish, whilst creating a swampy pond like environment at the top.
 
I need these plants to grow whilst floating. I won't be planting them or attaching to bogwood.
 
These are my conditions:
 
Tank: 400L
PH: 7
Temp: 26C
Light: 1x T5 Hagen Hi-Glow
Extra Nutrients: None
 
Would Elodea Densa or Crispa be suitable?
 
Both are very cheap, with it being tropical, I think Densa is better? But will it survive floating like Crispa?
 
Thank you.

 

[Tongue_Flicker]

I still think you should anchor it somewhere down if dont wanna plant it

 

[Abyss]

Nah, I really need it floating.
 
Read that it is completely fine like that?