technically you dont need any, but personally I wouldnt have a salt tank without. IMO
if you have 0 LR
then you will need to spend much more money on the mech filters to take the place of your missing LR
. Then from there, your costs going forward will be constant for service and replacment filters etc... and IMO
never as good as LR
All in all LR
is expensive in the beginning but more then pays for itself over the course of the tanks life...
If you want to be cheaper about it, get a good 20lbs of LR
.com, and a good 10-20 lbs from hirocks.com, and keep an eye out around your town for people getting out of teh hobby... you should get good deals from them.
I myself, went with 100lbs LR
.com rocks and 60lbs of Hirocks 30 rubble for sump and 30 premium for inside tank and support pieces for the LR
75g w/ 30g sump, 160# LR
, 60# sand: Inverts =18 turbos, 30 nassirus's, 40 blue leg's, 5 emeralds, 1 CBS, 1 skunk cleaner, 1 brown gulf shrimp? and various other LR
hitch hikers yet un discovered or un-ID
Fish=1 yellow tang, 1 yellow headed jawfish, 1 pink/blue shrimpgoby, 2 perc clowns.
Future fish = 1 sixline, 1 lawnmower blenny