New hang-on overflow

[mini-reefer]

Ok, I've been awaiting an overflow I got off ---- for a decent price. There are no manufacturer names or model numbers of any kind so I am not sure of the maker or model but it does appear to be professionally built. It came in today and now after doing ALOT of research while waiting for it to get here I find that I still have some questions. First I'll explain what it looks like:
Its got two sides of the same dimensions for each side of the tank. The front has the slots cut out for the water. The back compartment has the PVC that sticks through about 1/2". There is a clear U-tube that sits on the PVC snugly, and with it fully seated the U-tube sits about 3/8" off the front compartment floor. There are 2 adjustment screws that are inside to adjust the box height in the water. According to the seller it is capable of up to 400gph.
I've read about adding traps to the drain pipe or an air tube to the U-tube for noise levels. Will someone explain to me about these additions or send me in the right direction(a link)so I can become more knowledgable.
Also, my return pump will feed back about 170gph with the head pressure according to the manufacturer which is what I'm looking for. This entire project is for adding more water quantity as a whole to the tank along with a refugium. The tank filtration has been very sufficient since switching to only a DSB with ls/lr and a skimmer. Any guidance will help greatly.
Whew...
Mini-Reefer

 

[daluminum]

Thats a different type of overflow on that link.. i wouldnt use it in your situation.. I know exactly what overflow you bought. haha. I bid about $4.55 on it.. and I think it went for around $50 which is still a good deal.. but.. It will be pretty quiet already.. There is only about a 2" drop from the side inside the tank.. and your hood will kill that noise.. then on the outside of the tank.. the only noise you will hear is where the water get's drained into the downspout.. To fix this problem you can cut a piece of the sponge that goes around the outside of the pipe and plug the hole.. Basically what makes sound is when the water "drops" you want the water to touch the sponge shoved in the hole.. then it will flow to the sump queitly.. You can add 2 elbows to the top of this.. but its kinda scary.. because there isnt much capacity in that outer tank.. and I wouldnt want it going any higher than it has to.. so I would advise against the advice in the above link.. for your situation that is.. hook it up.. see how loud it is.. then try the sponge.. then try the syphon thing..
As for the air line.. this is used to suck the air out of the top of the U-tube to get the syphon working.. once you have all the air out... and a mouth full of saltwater.. you can remove the air tube and walk away..

 

[mini-reefer]

I think I'll go with the trap fashioned out of clear 1" tubing. As for the siphon starting I understand that as well. My ? is, What happens after a power loss? It seems to me that the pump will fill the tank, then the overflow will fill inside, then outside, then floor. Assuming I'm not there to suck out the water to start the siphon again. Is this the case in the particular setup?
Mini-Reefer

 

[javlavikin]

Check this out....
<a href="http://www.cyberreefguru.com/fish/ref/overflow/overflow.html" target="_blank">http://www.cyberreefguru.com/fish/ref/overflow/overflow.html</a>

(although the sump tank shouldn't be shown as entirely full in the first pic.)