is external box better than just pipes?

[treesprite]

What is the benefit to having a box attached to the back of the tank, instead of pipes coming directly out of the tank?

[Apcoleman]

A lot less real estate is taken up inside the display

[Fishie]

easier maintenance if you need to disconnect /reconnect ever?

[treesprite]

If I use an external box instead of pipes coming off the tank, does that mean I can put my internal overflow as close to the wall as will still allow for the gph rating of the pump? The water would then just flow through the holes in the tank, into the external box. Not sure of it would be noisy. I don't want noisy.

[AlanM]

You have to think about how you do it.  The Shadow ones from Synergy are probably the easiest and cheapest way to do it correctly.  DIY route would probably be silent and flow right on about the third attempt.  At least that's my experience with DIY-ing things.

[treesprite]

I did DIY C2C in both of my past 75g tanks. I did the second one differently, but it took a lot of adjusting with valves to get the water level right, to reduce waterfall and pipe gurple noises. But both tanks had just pipes without the external box.

[AlanM]

Yep, mine did as well.  It was a classic Beananimal design with three pipes out the back.  The box inside needed to be 3 inches or so from front to back.  If you're willing to do the added complexity of an inner and outer box  connected by holes through the glass you can get away with only about an inch inside the tank.  

 

Historically an outer box meant either having a slot weir cut in the back glass on the tank or a custom overflow inside with a custom glass box siliconed to the outside.  These days you can drop 150 on a pre-made inner/outer system that uses bulkhead gaskets to seal everything up.

 

For the inner/outer box design, if you want the holes through the back wall to be silent, they need to be submerged fully, which means the water level in the inside box needs to stay above the top of the hole through the tank wall.  The pre-made inner/outer systems don't leave a lot of room for this to happen.  Once you set the level that high you end up with just an inch of slack space which causes salt creep.  If I ever did a DIY one I'd make sure to drill low enough so that those connecting holes could stay well below the water.  A tall and narrow box doesn't seem like that big of a deal as much as a wider box does.

[treesprite]

My last C2C was only 1.5" from the back wall of the tank, and about 7" high, no pieces of pipe in it, water went straight into the holes and down.. The first one was 4" from the wall, and only about 5" high, but it had  holes drilled into it for the returns, so there had to be room for that plumbing as well. How far out i put it wil depend probably on if I want to put return pipes through it, otherwise they will have to go in front of it, sticking out further into the tank (because I would be using my return holes for drain holes, so return pipes have to go over the back of the tank).

 

I am thinking I can just take out the bulkheads and let the water go through the holes into the external box (taking out the bulkheads will allow for more flow). The holes I would be using include 2x 1" bulkhead  holes intended as returns, and the bottoms of those holes are about 6.5" down. The hole positions automatically rule out a ready-made internal/external overflow assembly. The actual drain hole is way up in a corner, sized for 1.5" bulkhead.... not sure what will end up happening with that hole, depends on the overflow design.

Edited March 22, 2017 by treesprite