I use locktite gel glue but its pricey. I am going to try and use the gel from the dollar store.
I used to use the cheap stuff, then it would just harden up between uses.... I buy either loctite, or I have been buying the IC-Gel from
http://www.bsi-inc.com/index.html The instaset accelerator is cool too, if your doing alot of fraggin. Spray, 1 -2, set frag, 1 - 2 - 3. Its done.
As for doing LPS, What are you fragging. If your doing a branching coral, then it might be best to do something with epoxy, or drill a hole in a piece of rock.