For the record, I work construction and have used caulk gun tubes of 100% silicone for aquarium repairs/adding
skimmer boxes/sealing bulkheads/you name it for two decades. The odor, texture, and I'd wager my mortgage; the very chemical
composition are no different than the product sold in a smaller tubes labeled "for aquarium use only." Cost isn't the factor to me; it's getting a good perfect bead right in the seam. With a caulk gun, I know the exact amount of pressure to apply to the trigger and speed to move the nose of the tube. Too much makes a sloppy job when you spread it with your finger, too little and you really need to wait for it to dry to re-apply more to the seal.
I'm far from claiming that I am a chemist, but I
have successfully sealed more tanks than are in any
LFS within 30 miles of me with 100% silicone in caulking tubes. I'd need some amazing evidence to change now.
