20g external overflow.

[spankyspam]

I’m looking to adding an external overflow. I’ve seen that people have just glued a breeder box to the back of the tank, and drilled 2 bulkheads into the tank. They do not have an internal box. Is this a good idea? I have the drill and box already so I would just have to buy some bulkheads and plumbing if I do it this way. But I want to be sure it works

 

[Peace River]

Normally an overflow would have an inside box and an outside box (e.g, Eshopps Eclipse) which give you multiple drain configurations like Herbie and Bean-Animal that have emergency overflows, but there are also commercially available inside-only overflow boxes (e.g., CPR Aquatics). Of course there are DIY variations to both of these. One of the challenges is getting the weir teeth width and height correct. I literally have "been there, done that" on all of the above and plenty more (both commercial and DIY) and they all have there place although the DIY options often take some extra TLC and tweaking over time. Another lost cost option that I have used in utility tanks is to drill the tank, add a bulkhead, and then add PVC 90 facing upward with some plastic screen around it to keep livestock from going down the overflow. Good luck with whatever you choose!

 

[spankyspam]

Normally an overflow would have an inside box and an outside box (e.g, Eshopps Eclipse) which give you multiple drain configurations like Herbie and Bean-Animal that have emergency overflows, but there are also commercially available inside-only overflow boxes (e.g., CPR Aquatics). Of course there are DIY variations to both of these. One of the challenges is getting the weir teeth width and height correct. I literally have "been there, done that" on all of the above and plenty more (both commercial and DIY) and they all have there place although the DIY options often take some extra TLC and tweaking over time. Another lost cost option that I have used in utility tanks is to drill the tank, add a bulkhead, and then add PVC 90 facing upward with some plastic screen around it to keep livestock from going down the overflow. Good luck with whatever you choose!

I was thinking a lot about the pvc facing up for the overflow instead of a whole box inside. Did u have success with that?

 

[TangerineSpeedo]

Just do this and save yourself some troubles ...
https://www.fijicube.com/collection...cube-low-profile-external-overflow-box-400gphI mean the utility way with the PVC 90 works fine, but you have to size it correctly with your pump or it will go in and out of siphon status, can be noisy. But public aquariums and aquaculture use this system all the time.

 

[Peace River]

I was thinking a lot about the pvc facing up for the overflow instead of a whole box inside. Did u have success with that?

Yes, it can be done. It also can also be noisy and put extra stress on the glass.