Seeking Some External Overflow Box Advice

[Yellow Eyes]

Hi guys, I currently have a 20g nano that is drilled for a herbie set up (2x 1" on back wall). However I built my own overflow box (poorly) and I am planning on replacing it. The current overflow box is 3.5" deep, 6.5" wide and 6" tall, so it eats up a good junk of real estate in an already small tank.

I was reading a build thread where someone asked about an external overflow, and it got me thinking :beer:

I've tried searching but I can't find much information on it so hopefully someone here can help?

How can I mount the external box on the back? (I assume I will drill the bottom out to run my two herbie pipes that way)

Should I still invest in a small overflow box for the inside of the tank (just enough to cover the holes for water to overflow before being passed outside the tank)?

Are there any references you could point me to?

Or should I just upgrade my tank (I am in college/in a rented house, so I was thinking maybe just a 40g :crazy1

Thanks!

 

[tidus10]

So, the issue I had with the idea of going external add-on (may have been my thread?) is how are you going to keep the fish out? A couple holes in the back of your tank and a small tank behind that (essentially) that is the only difficult part. Maybe do a light diffuser?

 

[SGT_York]

You just need a weir or damn on the tank side (can be really thin) and a larger box on the outside 4"x6"x6" is a good size. you should have acrylic on five sides to keep it attached to the tank. So you will need an additional bulkhead washer One for the inside glass, another for between the glass and acrylic box.

 

[Kyle918]

I have an external box on mine. It was pretty easy to attach. I used RTV108 Momentum silicon. Ordered it from Amazon I believe.

I have a bean animal on mine but I drilled 3 holes in the bottom of the overflow box and attached it to the outside of the tank. I am at work now but when I am home, I can post pictures of the internal box that I made as well for it.

The internal box is essentially the same thing as the external, just really shallow; I believe it sticks out into the tank just 1.25 inches, then an additional 0.25 inches because I covered the internal overflow with black acrylic to hide the holes and to match the black background of my tank. I didn't use the acrylic for the entire design because of the flexing that would occur with the weight of the water. I used 0.25 inch glass for both the internal and external overflow.

Also, I have had no issues with fish going over; just snails. I will buy a wrasse soon and I know they are more prone to jumping so he may go over from time to time if he hangs out up there as the internal overflow does not have teeth. I intentially decided against teeth on my overflow for various reasons.

 

[Kyle918]

Sorry that I took a few days to upload. I actually might have forgotten :spin1:

Here are the pictures.





This is after I silicon-ed the black acrylic to the overflow.