SCS1200
 

Ive always used SCS1200. Freshwater/saltwater/my own bathtub.... I have called GE and talked to a rep. They have been sued due to bond failure in aquariums so they added the "not for aquariums" to the tube. if you need the silicone to operate at near its peak tensile strength cleaning temperature bead thickness all must be perfect. Once weather shield gets a call from a lawyer about an aquarium that failed they will probably be removing the "safe for aquariums" from there tubes also.

Ive noticed a lot of aquarium/fish stores in Calgary actually have scs1200 for sale on there shelves..... I buy it from Calgary fasteners with contractor pricing for less than $6 a tube.

Just for fun
 

Well I was over at Pisces flatworm farm and snapped a pic just for fun. $18.99 for a tube. "do not use below water"...... it is what it is. And what it is, is very good silicone!
https://i.imgur.com/Bv4tz0Zl.jpg