submersed leaves in Nymphea

[Matan Golan]

Hi,
I planted a Nymphea ("rubra") in my tank a few months ago between some rocks. It grew a number of submersed leaves but in the past month or so it would only try to grow the floating leaves. The submersed leaves are now looking ragged and generally unattractive. I keep cutting the floating leaves before they reach the surface but it does not seem to help.
Any ideas as to how I can train it?

Tank specs: 200 litres, hard tap water, EI dosing, CO2 mist using inline diffuser, about 2.8 watt/gallon with T5HO, Flourite substrate with some peat underneath.
Thanks.

[rich815]

The roots may not be enjoying growing restricted between rocks. Perhaps move it and see how it goes? My green and red Nympheas are growing like weeds and did so even when I was lower light and no CO2, and I'm opposite that now...