ok well as for my tank i had it drilled in 6 seperate areas with a 1.75" hole which is so that it can handle a 1" bulkhead .... the holes are always bigger than the bulkhead size that way it fits through and u can run 1" pipping which is most likely the size ur guna wanna run
first pic is of the back of the tankive got 2-1" drain holes drilled into the back panel of my tank.... both are located in the middle of each side of the overflow box that way i get even flow from both sides of the tank, it keeps water moving around the whole tank....
so these 1" exits come out and angle to the center of the tank where they connect in a 2" T with adapters to make them join..... now this allows the 1" from each side to join in the 2" allowing for maximum suction for the pump below meaning it wont under feed the closed loop pump
after the T it drops down a 2" PVC pipe until it gets to the CL pump which is a Sequence Reeflo Dart great pump for a closed loop system lots of flow and low energy only 160W.... this pump is not meant for any pressure applications though or it loses alot of power
so the 2" elbows into the pumps 2" inlet then the pump shoots the water straight up a 1.5" pipe.... i located my CL pump in the very back of my stand centered and behind my sump... its hard to get to from the front without removing the sump but i shouldnt have to remove it ever.... anyways i did this to minimize elbows on the return any elbow on the return will slow down flow....
so the return then goes straight up to my Oceans Motion 4 way Version 3 1.5" inlet and 1" outlets then from the OM unit as u can see from the top the piping goes to the 4 other holes i had drilled in the tank.... 2 in the upper corners and the other 2 are in the middle of the tank through the top of the euro bracing.... i ended up wanting the 2 in the corner to return more at the mide level so i dropped down some piping to shoot the water in the middle.... the two in the euro bracing i used Omni-Flex return nozzels so i can adjust direction on the return...
this allows for pleanty of water flow in the tank and a nice alternating current
the Oceans Motion unit which is the silver cylinder thing has a motor which opens and closes two holes at a time which makes the random flow in the tank... IMO a great product!
my sump return pump is doing about 900gph so in total i think i have about 4000gph in the tank after loss of head pressure
heres some pics
first the exits Ting up
second the piping down to the CL pump
third the top of the tank where u see the OM unit and the returns to the tank
fourth one side where u see the drain and 2 returns