I used Por 15, worked a treat. Once the Fiber glass has laminated i was told its too hard to try and fill the cracks with resin again. The porkit was a peice of Piss and it ended up the small tin did 3 of my fiber glass tanks, its not thick and shittly like the other kits, it drys grey and looks just like steel.
I have also used methonal in it so it seems to stand up to anything. this shit is idiot proof.