Installing PVC pipe is pretty easy. The most common used is PVC pipe Sch 20. To start, draw a plan and specify measures before you cut the pipe (if you will, post your plans here at TRT....youīll get a lot of feedback....quality feedback !!). Count the amount of elbows, Tīs etc. and then go around it to try and minimize those turns (they decrease the actual
flow rate your pump is capable of delivering). Check your pump for head loses and get a rough estimate of your actual vs desired flow rate. If you decided howīs your final plumbing arrangement, proceed to cut pipe. Practice the assembly by dry fitting all the joints (PVC glue is not very forgiving....not much room for error). Get some sand paper and sand the gluing surfaces. Clean the residues from the sanding operation. Glue the pieces starting with those that are not specificly oriented. When you do the work, make sure not to twist the glueing surfaces. Just push as far as they can go. Clean if there is much excess coming out of the joint. If itīs not dripping, donīt clean it (the excess helps to seal). PVC glue is sort of a welding material. I donīt know the chemistry involved, but it will melt the material to make a perfect bond. This is prolly why many prefer glued joints than threaded PVC (done right, no risks of leakage). And donīt be scared, itīs not so difficult as it may sound. You just need to be careful. Donīt rush !!!
On the other hand. I would put a ball valve on each side of the tee. This way you can tweak the flow if you want at each side of the tank.
If you have overflow box or boxes you can install the return lines within the top 2" (from water surface) so if your return pump shuts off for any random reason, the backflow isnīt much. You should size the sump to take the additional volume from a potential back flow and avoid possible carpet/floor flooding.
Also, youīll need a ball valve at the pump discharge, so that you can can close it, and disconnect the pump in case you need (for service, maintenance, etc). In this circumstance you shouldnīt have backflow.
As far as pipe size, Iīm a little rusty on that subject, so I donīt think I can be of much help here. My return pump is a Mag 12, so my needs are different than yours. If I had to guess, you may need 3/4"-1" pipe for the return, but Iīm sure someone will chime in with a better answer.
To be honest! youīre right on track.
For the spray bar, there are different options. One is to place it as deep as you consider will suit your purposes. For example, if you want, you can run it to just about the top of your sand bed, to help move detritus to the front of the tank. You can have a spray bar to provide some corals with a gentle, laminar flow at a mid level, for instance.
The spray bar can come from your return line (the same one that comes from your sump). In this case, youīll need to drilla small hole just below the water surface for syphon brake (in case your pump shuts off).
You can have a dedicated spray bar on a separate powerhead for example (you donīt have to worry about the syphoning issue, provided you took care of other details in your return line).
This maybe enough for now. Maybe too much writing in a single reply, sorry !!!.
If you have many doubts, stick to this thread and ask lots of questions. Youīll come along nicely if you take it easy.
, I'm getting my new mag 9.5 pump tomorrow and i need some help as to how to run the pvc. i have never had a sump before so i have no idea as of what to get. what type of pvc do i need to ask for? and what size? i was thinking of comming off the pump and going back towards the back of the tank then having a 90 to go up and then have a "T" and have it go into the tank from both sides of the top of the tank. somewhere in there i as thinking of putting a 
