I went and check because I was not sure anymore everything I use is 3/16

For each level this is what I use (the rack being 5 tubs wide by 6 tubs high)

T T T T T T L
T T T T T T L
T T T T T T L
T T T T T T L
T T T T T T L
L T T T T T L

If you do a 1 column rack you would need

T L
T L
T L
T L
T L
L L

Aside from the tubbing, tank connector, valves and connectors you will also need those http://www.agselect.com/ED/showdetl....D=361&CATID=12 and those http://www.agselect.com/ED/showdetl....D=181&CATID=12