"Bob Alston" wrote in message
news:CWqbc.88256$Bg.86828@fed1read03...
So how do you know you have enough light? Generally the lights that come
with aquariums only have enough light for relatively low light plants. In
my experience, Myriophyllum requires fairly bright lighting, perhaps 3 watts
per gallon or more? So I would either look into getting more light or
replace it with other low light requiring plants like: Java fern, java
moss, anubias, etc.

Agreed.

pH = 7.8
KH = 15
GH = 20.5
NO2 = 0.01 mg/l
NO3 = 100 mg/l


Also, Myriophyllum is happer in slightly acidic and soft water.
Your conditions may well be too alkaline and hard for the plant to
thrive. (Even under ideal conditions, Myriophyllum Tuberculatum
is considered a difficult plant to grow and will not do well in many
tanks.)

BTW -- you should try to get those nitrate levels down. 100ppm is
definitely on the very high side where it will be toxic for at least some
fish species. Adding lots more plants will help in reducing nitrate
levels.

Cheers,

Michi.