How much does femara hinder gains?

How much if femara going to hinder my gains? I thought it would only take out water weight that I gain. Here is my cycle. I definately want to take femara because i dont want the water weight, but I dont know how much to take.
Weeks 1-3 25 mgs Dbol ED
Weeks 1-10 2cc's of test enath a week
Weeks 1-10 400 mg's eq a week
HCG every 3 weeks.

I was thinking about taking two pills of femara a week on my non injectable days. In order to prevent gyno and water weight. I dont mind a little water weight I just dont want a lot.
-Pete