Need Advice On HOB Overflow

[USMCSS]

So I have sold off all my freshwater fish and am taking the plunge into saltwater. I'm going to be using my 125 as a swim tank and it does not have built in overflows nor will I be drilling it. I am very experienced with sumps and their operation and same with built in overflows but this will be my first time using an HOB overflow. I came across a REALLY good deal on an Eshopps PF-1000overflow but I'm not sure if it has all the parts and whether certain parts are exactly what I need.

1. It has the two U-tubes needed but one is longer than the other as seen in the pic. I was hoping someone could tell me if the shorter one is going to be long enough to maintain a proper and safe siphon.

2. I have ordered new sponges for the overflow but my next question is about the white PVCtube in the overflow that has another small piece of acrylic tubing attached to the inside. What is the purpose of this piece? Do I need one for each side of the overflow? Which way is it suppose to be seated in the overflow, clear tube facing up or down?

3. It came with the white PVCtubes glued into the bulkhead fittings. Why would they do this and will this be a problem?

4. As I said, this will be a swim tank for a few semi aggressive fish and knowing that and the overflow I'm using, what are recommendations on the GPH pumpI should look into and what are your favorites?

Any other advice on this overflow and getting it setup and going would be greatly appreciated.

boldtogether

 

[adamsfishes]

I did a lot of research on HOB overflows, but I've since decided I will probably just drill.

My conclusion was that the KollerCraft TOM RP3 Overflow Box is the one I would purchase. I don't have any direct experience with it so as usual YMMV.

 

[convict360]

but...but...your clown loaches...? :O

 

[duanes]

I have PVC pipes in overflows, that help maintain enough water in the overflow box to keep siphon from breaking, water level must be above the end of the U tube.
If water flows too quickly thru the box, bubbles will form in the U tubes.
So both U tubes may be needed, depending on how powerful the pump is.
If they are 1.25 inner diameter one tube may suffice, if less, both may be needed to keep up with flow.
below is a 1.25 inner diameter U tube working.

and now the outside box, with PVC tube to help maintain water level.

I suspend a cap over the PVC tube to reduce noise, I am guessing the double tube in your pic may be a noise reduction technique (although I'm not sure). I have never used a smaller tube within a larger one.