Piecing together live rock.

for most rocks you can just use silicon seal or epoxy but I dont know if you can do this with live rock

I've never done it, but ive heard of using PVC rods. If you drill a hole the size of the rods on each rock then slide the rod into the bottom rock and then stack the other rocks on top of that.

This sounds doable and cheap enough. But like I said, I've never tried it...

You will definitely need to do something. Delicately balanced rock will eventually become an avalanche. In my tank, I just assembled it like a puzzle, fitting rocks into places where they will stay put. Takes time, but it will work. Fishing line, and the PVC frame will also work, as will plastic cable ties.

I like the idea of the fishing line as it will last indefinately but won't be too permanent to stop you from changing your setup in the future.

i`m new to marine and just starting to set my tank up i`ve researched alot about placement of rocks (as i`m currently aquascaping my tank at the mo)plastic cable ties and rods as mentioned above i have heard of but never tried. i ask at my LFS and a product i came home with was called milliput its like plastacine u mix it together then attach to rock where nesaserry it sets after a couple of hours and over night is rock hard this can all be done under water and i`m told is non toxic and can be done in the pressence of fish. i am currently using this and it seems pretty good and rocks or very stable and secure after milliput is completely set.hope this helps,but bear in mind i am new to this and at present i have no fish in my tank still loading it up with live rock at the mo.

joining live rock

Yup just go to your LFS and ask,i use bondfast putty.Just cut or pull what u need off,knead and the original green color will turn to white.Pieces of rock can be attached underwater.It hardens and cures under water and is reef safe.Can be used for frags but u have to incase some piece of the coral in it as it's not like glue.It amazing how hard this stuff sets up.