Jungle Val not growing toward top

[Averus]

I have some Jungle Vallisneria plants in my low tech tank, but for some reason they are not growing vertically.  They have sent out plenty of runners, so I know the plants are still alive, but they just do not seem interested in doing anything but sending out the new runners.

My tank has a ton of plants, and my other rooted plants are doing great.  I have plenty of root tabs in the substrate too. All of my crypts have come back after the initial melt and have a bunch of new growth, and my dwarf sag are getting bushy and starting to spread too.

I am a little puzzled here, all the stuff I have seen on Vallisnera is it grows like crazy towards the light.  I do have some frogbit, any chance they are making things a little to dim for the Val?

 

[Zenzo]

I would suspect that it may not have enough light to grow upward. Maybe try moving the frog bit out and giving the val direct overhead light. 

[Daniel]

In my 1930s aquarium the jungle val didn't grow much but sent out runners at first. Much later the runners suddenly grew long leaves. This aquarium has no overhead (artificial) lighting as sunlight comes in through the window it is next to.