Mp40

[Rogue951]

Maybe the 40 won't push enough water in a tank that long?
I find the 10 barely has enough push for the width of my 40 breeder which is 3 feet.

I'm assuming you read the instructions right?
just comes down to planting yourself on a chair infront of the tank, setting the dial, waiting, and if nothing, try another setting waiting some more.

In the end it may not be what you're looking for. It's not the best wave maker, it just does a decent approximation of one.