The current incarnation of the manifold is 1.5" from the sequence to the top of the tank. Then, it reduces to 1" for the perimter of the tank with the T pieces of the manifold reducing to a mix of 1/2 and 3/4 loc-line. The manifold is top flow only, I guess and the only flow that reaches the midportions and bottom of the tank is whatever turbulent flow is created by the manifold as the water crashes around from the nozzels. In other words I do not have any T's that extend any length down into the tank. So that is why I was considering the spray bar --- If I need to do that, I was planning on getting a sequence dart so again it would be 1.5" to the top of the tank reduced to 1" going over the edge and down to the sand bed, once I got to the sand bed or about 1" above it, I was going to reduce to 3/4 and drill several varying sized holes along the sray bar. Also the current manifold is only one hammerhead - I am going to be adding a second - since I already have the holes drilled....
hope this makes sense...
thanks much!