I'm working on setting up a standard 90 gallon tank that came with 1.5" bulkhead holes drilled in the back. I picked up a Fluval FX5 and want to utilize the holes for a nicer presentation.
My question is; can I plumb a 1.5" intake tubing and 1.5" return spray bar into the tank or should I downsize it to 1" tubing to maintain flow rates? I figure that the FX5 tubing is 1" ID and therefore the flow at the intake and return will be lower as the tubing diameter is increased. I'm including a sketch so it makes more sense.
Also, Where should I downsize the 1.5" tubing outside the tank to fit a 1" barb adapter? I can do it in spots A or B on the below diagram. The last question is; what is the best option for injecting co2? Can I simply drill a hole and add a brass barb fitting into the return to come out the spray bar? Or would it be significantly more efficient add an in-line reactor?