Planted Tank Guru
Join Date: Jul 2010
Location: British Columbia, Canada
I've kept several different varieties of Nymphaea over the past few years, and didn't find that the size of tank, water conditions, lighting, or fertilizing, etc., made much difference in how they developed and grew.
My experience has been that Nymphaeas respond quite dramatically to how you trim & prune them. You can keep them quite bushy, low & compact by 'training' them, i.e. immediately cutting off, at the base, any stem that starts pushing for the surface above the others.
Keep doing this each time a stem shoots up toward the surface & it'll 'learn' to stay low & widen out.
If you allow any of the stems to reach the surface, more of them will soon follow, and you end up with a 'leggy' plant whose pads are all at the water's surface.
I have photos if anyone cares to see them.