I have 2 Vallisneria Spiralis in my 29 gallon aqaurium and its not growing. I dont know whats wrong. I also have two apongogetons in my tank that grow like weeds! I dont exactly know my light wattage. It is flourescent and it is appropriate for a 29 gallon. The Vallisnerias arent dying, there still alive but there not growing. Any tips?