Croping Valisnaria

My Valisnaria G.are growing too fast and need to have their tops cut back.
Nothing in the literature I've seen advises against this, although I can't
help but think this has to weaken the plant.  I've been reluctant to do
this since they keep so many things in the tank balanced.

What do you folks advise?

Augustine Rodriguez
Elk Mound, WI, USA