BS3 Boil hop IBU's low

[tigerbrew]

OK guys, I know you've seen this before but I'm getting a 25% lower IBU calc with same recipe from BS2 to BS3 (BS3 lower).
The BS3 altitude is set to 0 and the utilization factor is set at 125% in both equipment profiles. Both are using Tinseth.
This is being seen with FW hops and long boil hops.
I cannot get them to match, what am I missing?
Thanks, Scott!

[Oginme]

Check your boil hop utilization into whirlpool setting in the equipment profiles.  If you have this checked, then is there a difference in the whirlpool time in the equipment profile?


Also, note that the hop utilization setting in the equipment profile is for commercial sized batches above 20 gal, otherwise it defaults to 100%.  You didn't state what your batch size is so I am not sure if this applies or not.

[tigerbrew]

The boil hop util in whirlpool is checked, without it checked the IBU's go even lower. WP time 50 min.
In BS2, Hop util in whirlpool is also checked, and same WP time of 50 min.
This is a Blonde Ale (low IBU). All hopping done in the Boil, and in early additions BS3 is lower?

I'll make a table showing addition and BS2 IBU, BS3 IBU:
First Wort: 5.1, 3.8
60 minute: 10.1, 7.0
30 minute: 2.8, 2.2
1 minute: 4.5, 4.6
Total IBU: 22.5, 17.6

You can see the earlier additions show the largest mismatch.

I'm using 125% hop utilization because my system is 20bbl.

Thanks so much for responses!
Scott