Internal Overflow Gasket Placement

[hyperfocal]

The fact that the slip fitting into the bulkhead might leak during a power failure never crossed my mind; even though I'm planning on having sufficient space in my sump to handle the potential excess water, I want to save that capacity for surprises -- not "spend" it on bad design.

Maybe the best solution is to make the overflow without a "back" and glue it directly to the rear wall of the aquarium, as suggested. The acrylic tank is currently empty so I don't have to worry about working wet or hurting any livestock. I was reluctant to go this way at first... having a plug-in/bolt-on overflow seemed a lot more flexible.. but it seems that the flexibility sacrafices reliability. That's a trade-off I'm really uncomfortable with.

 

[javajaws]

My overflow box is "bolted on" by 2 1.5" bulkheads with double gaskets each...no problems. I don't think you will have any problems with your original plan.

If you can go with the reversed bulkhead, that would be good as well. FYI, Barr Aquatics sells premade overflow boxes and plumbing kits like this...

 

[Atomahawk]

If you want to be able to remove the box for flexibility it's really simple to do. Proceed as your first pic except replace the A gasket with a piece of epdm rubber that would be the exact dimension (or a bit larger all around and trim off excess once placed) of your back panel of the box. Cut out a hole the exact dimension for the bulkhead to fit through and Use magic lube silicone on both sides of the new seal you made, you only need to put a small amount around the hole where the bulkhead fits through. Once you tighten everything up that silicone will compress to an extremely fine seal. Whatââ"šÂ¬Ã¢"žÂ¢s nice about this setup is it keeps the rubber ply-able and is not permanent.

If your wondering why I suggest you replaced the gasket is to ovoid anything growing or accumulating behind your box. Which you will never be able to clean without removing your boxt. Plus your increasing the over all seal size and supporting the box properly, Which A is not giving you at the moment.

Warning, don't use regular aquarium sealent, you'll freak out the day you need to take out this setup.

 

[hyperfocal]

I like the idea of a full-sized gasket between the back of the box and the aquarium wall -- any idea where small quantity EPDM sheet can usually be found? Maybe a pond supply store?

 

[BeanAnimal]

IF you use an EPDM rubber gasket that is the same shape as the box back, then you do not need any sealant.

The reason that picture 1 would fail is due to the gasket "A" being distorted by the weight of the box pulling down on the bulkhead and hole in the tank.

 

[javajaws]

Actually, depending on the height of the water in the overflow there may actualy be "lift" instead of a downward force due to the displaced water. I haven't found any negative effects either way however. But then again I'm using 2 sched 80 bulkheads and that box don't wiggle at all.

 

[hyperfocal]

Hey Java, are those 2 drains plumbed together? Do they drop in parallel to the sump? Also, do you have trouble with muck forming in the gap created by the gasket?

I've got the extra bulkheads, and having two drains off the overflow to add stability is certainly an option if I have trouble finding the gasket material locally.

 

[javajaws]

You don't really want to know how I have this thing really plumbed. But the short answer is...the 2 drains drain separate down into the sump. No problems with muck or anything else so far.

 

[hyperfocal]

Heh, some 5-dimensional non-Euclidian PVC universe where the overflow somehow ends up downstream from the return? The mobius-strip of plumbing?

Good to know about the lack of muck. Thanks.

 

[BeanAnimal]

my mind is a euclidean plane bent into a mobius loop that follows a euler circuit through my mind...

Then again I did not do so well in math because I was more interested in the teaching of Jack Handy and his deep thoughts.

 

[Atomahawk]

EPDM rubber can be found in most lawn and garden places that sell posnd supplies , even HD or Lowes I assume when in season. I always have some here as it makes great gaskets and is dirt cheap.

The reason I suggest the use the Magic Lube is simply out of precaution, sometimes epdm is a little imperfect and can be a bit more ridgid than I like, the lube adds a bit of softness to it. Plus I dont like to do things twice. I Teflon all my fittings even though I know it's not always required

 

[BeanAnimal]

Certainly no problem with using the lube... and Ido understand not wanting to do things twice.

Bean