Help with Five Star Defoamer 105

[alcab]

I used some Five Star Defoamer 105 during my last batch as I have had problems with boilovers. I had 16 gallons of pre-boil wort in a 22 gallon boil kettle and added 16 drops of Defoamer 105 when the wort reached 190F. While it did help some, it still boiled over. See pics below. Those of you using defoamer successfully, I would appreciate some advise as far as dosage and when to add it. Thanks in advance.

 

[day_trippr]

From AHS:
"1-2 drops per gallon. Do not exceed this dosage or your beer will exceed FDA limitations for silicon content."
I checked a half dozen merchant sites and the ones that bother to mention the dosing rate were consistent with the above recommendation.

I use Fermcap for "tight" starters where two drops in ~1.7 liters is marvelously effective, but I've never used anti-foam agents in the kettle.
I just put my first hop addition in and then hang around the BK when the temp hits 208-209 or so and apply the throttle when the rolling gets going...

Cheers!

 

[RM-MN]

Turn your burner down as soon as you see the top of the wort starting to move under the hot break material. That cap of foam is like an insulating lid and won't let the heat out. All you need is a slow rolling boil.