Like I said in my earlier post, I have used the fosroc and the holdfast, one is smelly one is not, and they are both fine, the advantage in usuing the holdfast 202 clear, is it dries much clearer and doesn't go opaque with age.
JMO, but any of the 3 above would be fine, plus what you have to remember that for the companies to put "Aquarium Safe" on the product it needs to so, and extensively tested, and if you find it not to be so then you are eligible for compo under the fair trading act as the product is not " Fit For Purpose"
B