Adding an overflow box - prevent leaks?

[riz94107]

A couple months into my first tank (65 gallon acrylic, drilled) and I finally get why folks use an overflow box instead of draining directly from the main tank into the sump. I think I'm ready to install an overflow box, but I'm a little concerned that I don't fully understand the right way to gasket it.

What I have now: two 1" bulkheads, with one as the main drain and one as an emergency (dry). It's working relatively well, with the major downside of not having the control that a limited-volume overflow box will give me. (I'm the sort of person who sometimes has to _do_ something in order to grasp the tradeoffs). Meaning: it's loud. I have no way of tuning it to silence without risking a flood. (See the current setup here)


What I'd like to do: Add an external overflow box, with an internal weir. What I'm envisioning: a box which is fed through the two existing holes, and converting the not-really-herbie style drain for an actual-beananimal-style setup from the external box. What concerns me is the two extra pieces of acrylic (the internal weir and the external box) that the bulkhead will have to go through. Where do I put gaskets? I envision keeping the flange on the inside of the tank (inside the weir) and having a gasket there, but do I also place a gasket between the tank wall and the weir wall? What about in the overflow box itself - do I put a gasket between the nut and the wall of the overflow? What about between the overflow and the tank? If I put gaskets between tank wall and weir/overflow, how thick/thin should they be?

I see three potential options:


1) nut|overflow|tank|weir|gasket|flange

2) nut|gasket|overflow|tank|weir|gasket|flange

3) nut|gasket|overflow|gasket|tank|gasket|weir|gasket|flange


I would really like to choose the correct one the first time and avoid unnecessary leakage. Thoughts? I will be building my own overflow box and weir so I can drill the holes with the correct spacing.

 

[Lsufan]

If u do both boxes out of acrylic then u would have a gasket between the glass & acrylic on both sides of the tank. It also wouldn't hurt to have one behind the flange of the bulkhead where the gasket would normally go.

So it would go flange-gasket-overflow-gasket-tank-gasket-overflow-nutt
U may be able to skip the gasket behind fle flange but u definitely need one between the overflows & tank on both sides of the tank.

What I did was made the internal wier out of acrylic but I made the external box from glass & silicone fit to the tank. That way I didn't have any potential leak points. If the bulkhead that holds the interior box on leaks it's no big deal because it goes into the exterior box. I was able to make both of my boxes bigger then the manufactured boxes because I only have to rely on the bulkheads to hold the internal box , they don't have to support the wieght of both boxes

 

[ca1ore]

So it would go flange-gasket-overflow-gasket-tank-gasket-overflow-nut

I just bought a commercial 'ghost' overflow and that is how it is configured - 3 gaskets per connecting bulkhead.

 

[riz94107]

I just bought a commercial 'ghost' overflow and that is how it is configured - 3 gaskets per connecting bulkhead.

OK so maybe not one on the nut then? ... I guess that makes sense.

Sent from my SM-G900T using Tapatalk

 

[ca1ore]

You don't ever want a gasket under the nut. It distorts as you tighten and actually makes it difficult to properly tighten said nut.

 

[Lsufan]

Is there a particular reason why u want to build the external box from acrylic instead of glass. I'm not certain but I think your tank is 36" long. I would want my boxes to be atleast 24" to 32". U have to be careful not to make the exterior box to small. That was one of the issues with the manufactured boxes when they came out. The exterior box was to small, u were able to cram the plumbing in them but the small amount of water in the box would cause consistency issues with the bean drain. Some of them are better now, I believe the one calore just purchased has a 36" wier & a 36" exterior box. The 36" exterior should be way more consistent & take care of the issues some of them used to have.

There is a few reasons I asked about making the exterior box from glass. For one it will take away any chance of having a leak from the pass through holes. Another thing is it looks like your holes are drilled pretty close together on your tank. If u want the bulkheads to hold both boxes in place then u are going to have to make a really small overflow box unless u plan on drilling another hole so u have 3 bulkheads holding them in place. It doesn't take much to hold the wier in place but the exterior box is pretty heavy. If u make the exterior box from glass then all the bulkheads are holding is the wier.

I wouldn't want the boxes to be less then 24" but preferably bigger. I don't think those two holes that close together will support two 24" to 36" boxes.