circulation for 120g

[Ruth]

Not sure of the length of your 120 but I have seen wave boxes in action and IIRC they are designed to work best on a 6' tank.
If I were you I would go with the 2 X 6100 on a controller. This also gives you more options to move them around and place them exactly where you want them to give you the effect you are after. Definately get the magnetic holders for them if you decide to go this route as the hanger that come with them are a POS IMO.