just measure from down inside your sump to the top of your aquarium that will tell you how much tubing to buy and no you dont want alot of slack in the tubing just a little. and yea a ball valve is just a few dollars i would pick it up incase you want to slow the flow. make sure you get the ball valve fitting that has a 3/4 inch barb on each end so you can slide your 3/4 inch tubing on it. and get 3 adjustable clamps one for each side of the ball valve and 1 for the return that hangs in the tank it just makes sure your tubing doesnt slide off the barbs and come loose and cause a water leak.
i would wait until the overflow box arrives so you know what size a tubing it needs if it is 1 inch then you need a 1 inch bulkhead for your wet dry filter if its 3/4 inch then a 3/4 inch bulkhead if you wait you wont have to make alot of trips to get this stuff you can do it all at 1 time when you know exactly what sizes since the tubing you cant return if its the wrong size since they have to measure and cut it off the roll.
i would wait until the overflow box arrives so you know what size a tubing it needs if it is 1 inch then you need a 1 inch bulkhead for your wet dry filter if its 3/4 inch then a 3/4 inch bulkhead if you wait you wont have to make alot of trips to get this stuff you can do it all at 1 time when you know exactly what sizes since the tubing you cant return if its the wrong size since they have to measure and cut it off the roll.
