DIY Sump Questions

[gio28]

Im about to build a diy sump and i have actually made some plans for it but i have a few questions before i do.
First off my tank is a 36 gallon bowfront that i am about to put on a 46 bowfront stand. this leaves me about 36" of space underneath the stand for a sump. i was thinking of getting a 20 gallon long tank as my sump because i could fit more into it cause it has more room in the different chambers cause of its length. is this a good size sump? should i try to go bigger?
I dont know what size pvc and tubing to use to build my sump either. the overflow box i was gonna get has 1" bulkheads so i was just gonna go with that size for all of the plumbing. or should i do something different?
i know there are a few ways that the sump/tank can flood. the only one i dont understand is when the intake siphon breaks and the pump pumps all of the sump water into the tank. as long as the intake U tube stays underwater on both the tank and overflow side will it restart the siphon once the power goes back on?
i know i need to buy an overflow box and a pump...but what about a return U tube?
finally here are the plans for my sump. please tell me what you think

 

[i<3reefs]

Correct, the U tube is part of your overflow box, and will stay primed due to two reasons.
1. The overflow box in the aquarium will retain water in it.
2. The hang-on tank box is plumbed with a tube that a sponge sits on. That tube also retains a water level in the hang-on box.
General Info: That sponge is called a fish saver, because fish can get sucked into the back box. The sponge keeps them from washing into the sump.

 

[gio28]

thanks for the reply...i've been researching all the ways to prevent a wet floor but was unsure about that reason.

 

[i<3reefs]

Yeah, I've had the wet floor experience. The first time was a little over 7 years ago.
Once you have your refugium/sump setup, you absolutely need to simulate a power outage by unplugging your sump pump. See what happens, based off what you see, you can adjust your water level in your DT higher or lower.

 

[gio28]

yup..thats the first thing i was gonna do. thatd be a huge pain to come home and clean a carpet soaked in saltwater.