I take it that its 80mm in diameter ? , also what is the wall thickness ? anything over 6mm would be good enough without sand but filling it wont hurt .
Just be sure its washed and very dry before you put it in as rust will happen inside very quickly if its salty or damp , I have done a few and its a good idea to fill to within 25mm of the top and put a 10-15mm thick layer of silicon rubber on the sand to stop any water getting in after its set up ( dew or condensation ).
How is it bolted to the base ? , dyna bolts ( good ) , cam sets ( better ) or rods set into the base ? ( best ).
Will you be putting some grout between the base and bottom mounting plate ? .
What mount and scope are going on this pier ? .
Sorry for all the questions but the sum of the whole makes for a good solid pier .
Here is one I made and fitted for a friend here in Perth for his observatory , its 100nb ( 114mm o/d ) x8mm wall thickness and 1100mm tall , its not filled with sand and is camset down with 4 off 16mm x200 threaded rods , it does not move !! , solid !
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Brian .