i recently got some new frags to put in my tank, but have been having trouble attaching them to my rock. i got this stuff called hold fast from my lfs, but apparently it wont cuzz it doesnt harden right under water or something. i really dont want to have to pull out the rock to dry it first, cuzz it would be a pain trying to organize it again . does anyone know a good way of attaching them under water? thanks for the help.