glue

To do any fish catching or bottom cleaning in my tanks takes a rather large endeavor of energy and time. The main drain of both are the large stacks of rock which I have to remove one at a time from the tank, one after another, over and over.. So my idea at this point is to pull all the rocks...

Now i have been back and forth with making my own 3D BackGround and glueing some slate rocks and making them like a 3D backGround. Has anyone glued rocks together to make a whole setup if so can you share your experience or any advice you can give me would be greatly appreciated i want to figure...

I glue a bunch of PVC pipe together to make hide outs for my cichlid grown out tanks. How long do I have to wait after glueing for it to become safe to put in the tank?

When you clean out all the old silicone, the glass is still connected but there is a fine crevice or void between the pieces. What's holding it together? Would it help or hurt to run a bead of "crazy glue" down between the glass before the final silicone sealer?