55 Gallon Tank Build

I'm Jeff and I fairly new to the hobby. I started at the beginning of the year and I'm obsessed! I have a 20 gallon nano reef going right now and a 2 gallon pico reef for my desk at work. both tanks are running great and have been for months.
Anyway on to my problem....I bought a 55 gallon tank and stand from my LFS (Royal Aquatic) in Flower Mound, TX. We were going to have the LFS drill it but there was a whole mess and it didn't get done. The short version is he threw in free drilling and paint with the purchase and after two weeks of waiting for him to do it, we finally just picked up the tank (no drilling and no paint) with no explanation on why it wasn't done and a general feeling of "we don't care" on their part.
On to my problem. Since the tank was not drilled I am going to just do it myself, since all the Aquarium stores and glass shops in the area will not guarantee they won't break it. I figure I trust myself better then some guy who has no vested interest in the tank or the financials of it. so I went to Aquacave.com and bought a 1 3/4" diamond drill bit and 3 x 1" bulkheads. I also bought 4 Loc Lines, 2 for each return hole. What I want to do is have 3 holes on the back pane of the tank. I want one hole in the center of the back pane of the tank for a drain and the one on the left and one on the right for the return lines from the sump/fuge.
The reason I want it this way is out of necessity. The LFS told me it was a Marineland brand tank (cannot confirm, no sticker on tank or stand at all). He said that all Marineland tanks (in his experience) are tempered on the bottom pane. He showed me a tank he had set up for his QT in which he had a drain on the right and a return on the left. I thought that would work good but I thought the drain in the center and returns on the sides of the back would look great. Especially when placing an overflow box over the drain. This way the bulbous overflow will be in the center of the tank with Loc Lines on the sides for water movement as well, which will have good symmetry.
So I got the overflow box, which I will Silicone over the drain hole in the center.This overflow box is the black part off of an Eshopps HOB overflow. I Cut off the back of the black part and sanded it down with a Dremel. It looks great BTW!
My problem arises from a the plumbing aspect of this. It's a bit confusing and a little overwhelming the first time around, especially when your doing it all on your own (I got no fish friends.... ), Lots of information out there but this specific kind of build is hard to describe thus it is hard to find much information on it. I got a Hydor Centrifugal Universal Pump, 740 gph from Pet Supplies "Plus" for $20!!!! Amazing deal, so I got the pump and the LFS owner from before told me that the pump was plenty good for my tank. I have a 10 gallon refugium/sump that I built from an old tank I had, but now I'm thinking I need a 20 gallon long. What do y'all think?
I also am confused on the PVC parts and the size of the piping. I am afraid I may need to buy yet another drill bit. I was thinking I should maybe make the return lines smaller than the drain line? should I do that?
The pump has a 5/8" output and the LFS owner said that it would work okay with the 1" bulkheads we were going to have. I have no idea how that's gonna work. I need some input on that please.....
Another reason I was think of making the return lines smaller is because I cannot figure out out to connect 2 x 1/2" Loc Lines to a 1" bulkhead hole with threads. I could not find a part for this online. Which is further made difficult because I have no idea what I'm looking for. name? Item? Am I crazy? Help?

ughh...just typing this is already frustrating. I am confident about drilling the hole. I'm pretty good with tools and I love precision work. Its really just the plumbing that's getting me down. I Guess it cannot be that hard I mean plumbing is not exactly open heart surgery. This is just made further difficult because none of the LFS I go to nor Home Depot or any of the likes have all the parts I need. Online has obviously more but I hate waiting that long only to discover when I get them that they are not going to work, or I need another part or I forgot a part.

In summary I guess what would really help is an outline of the pieces/parts you guys would use for this particular set-up. Should I use 1" bulkheads /piping for the drain and returns or should I use a smaller size for the returns?
How can I attach the smaller Loc Lines to the bulkheads?
Will that pump work for this system? If so How do I connect it to a larger/smaller piping(depending on the size of the return pipe)?
Is there anything I have failed to think of?
I was told I should have a GPH thru the main display of at least 10 its volume, which the 740GPH pump would give me, However I am aware that the actual GPH will drop based on the piping and amount of elbows and valves I use, and if I use adapters from larger to smaller pipes, also how fast the water moves through my fuge. What will give me the least loss of GPH for this set-up?

I know this is a lot of questions, I guess I could have broken this up into a few posts, but I'm hoping to meet someone with a wealth of knowledge that doesn't mind sharing some guidance with me. I wanted to make sure I provide as much information as possible in order to get the most educated answers. IF you read all of this thank you so much already. If you answer then your a saint.

Thanks a bunch guys, I'm so stressed about this! :confused1

 

Hi OctoPunk and welcome to 3reef.

Jeff is my ex's name but I will not hold that against you. j/k

As far as plumbing I know absolutely nothing. :-/

Someone will come along that knows of what they speak. Relax and go slow. We understand that desire to finish and move on to the next step.
It's a hobby not a race, you will get good advice.

 

I used 2 inch for the drain on my 55, it flows through the bulk head to a "T" the top side of the "T" has a cap with a small hole drilled in it. The bottom side has a straight piece of PVC, that piece of PVC goes down to a 90 then to a straight piece to a "y" then to a gate valve then a straight piece to a 90. I have flex tube running from the end 90 and the y into the water. they ends of the flex are both submerged. I am using a 20L for a sump divided into 3 sections. The skimmer on the left, the return in the center, and a small refugium on the right. The gate valve controls the flow into the fuge. I am using an EHEIM Compact+ Pump 3000 return pump which is about 792GPH, I am using 5/8" flex tubing from it to solid PVC, to a check valve then back to PVC to flex to the hang on the side jet.

The 10G is ok, if you are just doing a sump with no refugium, but if you are contemplating the refugium the minimum I would use is the 20L...

Do not forget the check valve for your return line. I'd use 5/8" vinyl tubing and a ribbed "Y" for the split. Make sure you get good stainless steel clamps for the vinyl tubing, I got some from Lowes that said they were stainless and they started rusting immediately. I'm not sure how much pressure you would have making it into the tank what is your head height?

I am pretty sure I am using 2" for the drain, I will have to check when I get home. I hope that all makes sense.

 

Welcome to 3reef! There are many plumbing experts on here and I am definitely not one here's a bump for your question!