Thanks everyone for being so nice!
@Matiller : I trim HC two times after plantation. The first time is after about a month when I cut only the higher stems and if it's needed I plant those stems in empty spaces. The second and final trimming is after another month and this time I trim all the carpet by cutting all the stems.
I usually keep the setup for three months, and then a make a new one.
This time I made an exception and I kept it for 4 months.
It is good that you have more watts, but this way the plants will grow faster consuming more nutrients, and you should test the water parameters to avoid having algae.