46 bow front reef setup plumbing questions

[walletbmw]

I am in the final stages of setting up a 46 bow front reef and have all plumbing except a pump (need to purchase mag 5 sump pump). I have an overflow box and 1" pvc as the drainline to the sump. Return plumbing is 3/4" black plastic tubing. I wanted to know how to prevent a flood should the power shut off or the pump fail? I want to put the equipment on a battery backup (anyone have experience with this, recommendations?) as well as possibly put a check-valve in the return line, would this do the trick? If so where would i purchase this and what's the best way to install? also with respect to PVC and coupler connections, do you all glue them or simply allow them to fit snuggly without glue (i'm thinking not enough water pressure to worry about glueing, plus issues with toxicity of glue to fish, etc). Are there any other methods for attaching the fittings?
Thanks in advance for any help,

[walletbmw]

Also, have never used an overflow box before, how do you recommend best getting the siphon going? thanks.

[Staplesofficewar]

Wallet,

As far as preventing a flood, in relation to the overflow box, once the water inside of the tank falls to a level where it does not flow into the internal overflow, the water will stop flowing through the u-tubes and hence stop flowing over your bulkhead / standpipes.

I would not recommend a check-valve to prevent water from flowing back down the return line. I would put a small hole (16th inch or so) in the return line slightly below or right at the level of the tank when the pump is running. When power fails, the tank level will begin to fall and the hole will act as a syphon break.

I glue most of my fittings - anything where it can leak on the cabinet or floor. I use hose clamps and glue to prevent catastropic failures.

Use a small peice of airline, insert the airline into the utube to about the center. Place the utube into the running position (with water in both sides - water has to cover both ends at all times). Gently suck on the tube to pull out most of the air. When the pump starts running, the remaining air will be pulled out with the flow.