Heres something helpful from Ed's link.
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not at all...I work in a hospital...and never worked for them. Just something they sent me long time ago and figured i'd post it. GE II has better all round (plastics, rock...etc.) adhesive properties than GE I. Although GE I and II rate glass binding at 7, GE I holds glass better (and this is not GE telling me this, I discovered this myself along with many others. Both can be used, you just need to get the windows and doors (blue tube) and not bath and kitchen (red tube, has mildew prevention, fungicides..etc.). The one difference between GE I and II besides binding properties is the way they cure. GE I cures via acetic acid and GE II via ammonia. I just figeured I'd post this stuff to clear the confusion I thought everyone had known. The disclaimer about not for aquariums is, from what i had known to be circulating (not sure of the truthfulness about it though) is that GE was sued when a big aquarium fell apart and lots of water damage...etc. to this persons house. Now the questions remains whether this person applied the silcone properly and allowed it to cure properly before water was added. I know i leave it for at least a week. From what i've heard (again not sure of its validity) is that AGA uses GE I and the disclaimer previosly mentioned seems to point that without naming AGA. Take all this for whats its worth...just additional information. I've always used GE I without problems and many advanced reefers use it to. Hope this clears it up.