Belgian Wit. How to increase bitterness?

[Gort40]

I would prefer the taste of my Belgian Wit to be more bitter. My recipe, (for a 2 1/2 gal. batch), calls out to use 1/2 oz. Columbus hops for bittering at beginning of boil and another 1/2 oz. at last 10 min. of boil.

 

[AlexKay]

Half an ounce of Columbus (AA ~%15?) at 60 minutes should be plenty bitter in a 2.5-gallon batch. If you want more bitterness ... add more Columbus! (or any other high-alpha hop).

IBU Calculator Beer Bitterness - Brewer's Friend

Columbus at 10 minutes seems a little non-standard for a Wit, where you want noble hops, or English varieties, maybe.

 

[AlexKay]

I'm just seeing this is your recipe. Where did it come from? My last Wit had 3 g of Magnum, so about 20% of what you're thinking about.

 

[CascadesBrewer]

I agree with the comments from @AlexKay. A simple test recipe shows around 54 IBUs from a 60 minute boil of 0.5 oz of Columbus, and another 23 IBUs from a 10 minute addition for a total over 75 IBUs. Have you brewed that recipe before?