Undertow pro is a 8 site system standard (CONTACT FOR BIGGER OR SMALLER UNITS)
using bulkhead fittings with and our custom made riser pipe that attaches to the return fitting allows you to have height fluxuation from bucket sets while maintaing water level hight the same. 
each bucket also has its own feedline valve to assist in even flow by the ease of turing a couple knobs. The water height control fittings are removable as well adjustable giving you the control while you also have extreme flexabilty with sets of 2 as there is a return per every 2 buckets . this unit includes 10 1/2' ball valves 4 3/4" ball valves and over 50' of tubing combined. 
Of course like always all grommets are pre-installed for you. (bulkheads you will be required to install). max length 
comes with water pump/ commercial grade air pump, air stones, 50' of airline, starter rockwool cubes and clay pebbles. and more!