Not always, some have mold/mildew inhibitors in themHow about the one from home depot are they ok to use
+1 again- but if you do go to home depot --make sure the label specifically points out aquarium safe-- BUT you can get the silicon Kathy pointed out for the same price- if not a little less and is meant specifically for aquariums.
Not always, some have mold/mildew inhibitors in them
Best to go with one you are sure is 100% is reef safe.