Late Malt Extract Addition and Hop Adjustment For a Belgian Wit

I'm planning to brew a belgian wit in a few days and I plan on using late malt extract addition to lighten up the color. I know this requires less hops to achieve the same bitterness, and for this style in particular I am quite concerned about potentially overbittering it. Are there any substantive calculations i could make to determine this?

My recipe so far for a 3 gallon batch and a 1.5 gallon boil is:

0.5 lbs Flaked Oats (steeped)
3 lbs Wheat DME
1 oz. Hallertau (1.5 AAUs) at 60 min.
.25 oz. Cascades (6.60 AAUs) at 30 min
1 tbsp. Coriander at 15 min
Fresh Zest of 2 Oranges at 15 min.
Wyeast Belgian Wheat 3942

Say if I start with 1 lb. of the extract, and add the other 2 lbs. with 15 minutes left, would those hop additions make it too bitter?

Also would it be advisable to add more of the extract later and maybe reduce the hops overall. For example, 0.5 lbs of the extract at the start, and 2.5 lbs added late with say 0.5 of the hallertau and 0.25 of the cascades at the same times as above.

I'm not incredibly worried about color, though it would be nice to get that pretty light, cloudy color. However I am quite concerned about overbittering it and not having the belgian wit I want. Thanks!

I use a program called "beersmith". It calculates the bitterness, and allows you to adjust the bitterness IBU's for last extract editions. It even has a colour guide to let you know the likely final colour of your beer. Also automatically calculates alc %, estimated gravity etc. Worth checking it, it has a 21 day trial.

Where did you find 1.5AA Hallertau hops?

Is there any reason why you're only doing a 3 gal batch?

Looking at your recipe:

0.5 lbs Flaked Oats (steeped)
3 lbs Wheat DME
1 oz. Hallertau (1.5 AAUs) at 60 min.
.25 oz. Cascades (6.60 AAUs) at 30 min
1 tbsp. Coriander at 15 min
Fresh Zest of 2 Oranges at 15 min.
Wyeast Belgian Wheat 3942

I would boil 1.5 gals and add 1 lb of malt and the hops, boil 45 mins.

Remove from heat add other ingredients...

I use 3AAs for 5 gals so yo may want to up the Hallertaus to 2AAs.

At 30 mins the Cascades will add bittering and flavoring to the brew. At 6.6 AAs they may overpower the Hallertaus and make the brew more like grapefruit and not orange.

I got the 1.5 AAU Hallertaus from Midwest Supplies. And 3 gallons, just because it's a bit more feasible, and easier to try different things, although it is a little added work in scaling the recipe down.

So let me see if I have this straight, you said to add the hops at 45 minutes, so adding the cascades then would lessen make them less over powering and grapefruitish? I would have thought the opposite. What I was going for with the cascades was a slight, citrusy flavor that I thought would complement the style well. Thanks!

Not quite right...you can add the Hallertaus at the beginning of the boil as planned.

These are general guidelines that many brewers use:

In a 60 minute boil you get the full effects of the bittering from the hops.

At 30 mins only half the bittering and (the full) flavor of the hops.

Any time closer to the end of the boil will result only in extracting the aroma from the hops, none of the bittering, and maybe some flavoring (depends on amount of time is left of the 60 min boil).

There is also a hop bittering chart on the forum (somewhere) that basically depicts the same info. maybe you should cut and paste a copy of it for your brewing library.

Since you are looking for more citrus then adding the Cascades at 30 mins would do that for you.