I agree.Yes, very good color! Although I really like the light color v. Candidulum also!
A plant cultivated in a mix 60/30/10 rockwool/sponge rock/charcoal. The sponge rock I use is synthetic, it is a popcorn expanded clay special hydroponic.
I use 8-16 mm Gold Label hydrokorrels (www.specialmix.nl) made in Holland. I discard the smaller and the larger korrels.Do you have some info on the sponge rock you use? I use perlite in my mixes but particle size is quite small, would love to get some coarser stuff.