is this the right silicone?
 

i got premium waterproof silicone from walmart. its a walmart brand and is called silicone 2 clear. for window door attic and basement. it says 100% silicone on the bottle. it says 100% silicone is 100% water proof.
here it is
GE White Silicone II Window and Door Caulk: Sealants, Fillers & Adhesives : Walmart.com

First it is white not clear. Second for an aquarium I would never use anything but aquarium safe silicone, without knowing for certain that it was safe

mine says clear and 100% silicone

GE Silione I
GE Silicone II
If it has any mildew inhibitors in it, its not the correct type of silicone.

First of all I want to tell you that the GE white silicone II you want to show through the link is not operating there, I mean that display it is temporarily not available.

GE Silicone I is clear and safe to use although it may say not for aquarium use.
More of a disclaimer for the product or ..use at own risk.
Have used the GE silicone I to seal/repair tank's with no issues.;-)