External overflow leak - how to fix it?

[mattruggiero]

Hey guys - I need some advice.

When designing my tank I decided to change it from the dual overflow design it came with to a C2C internal overflow that extends the length of the tank (72") w/ an external overflow box which is about 24". I drilled three holes in the back of the tank for the 1.5" bulkheads, installed both overflows and everything looks good. The bulkheads are used just to move water from the internal to the external overflow and connect them. I also have the external overflow braced w/ some wood so the weight isn't on the glass.

Well, I have been testing the tank for leaks and I keep having very small leaks coming down the backside of my tank between the tank and the external overflow. I initially thought the bulkhead gaskets on the inside of the tank were faulty but now I'm thinking that it's water coming from the external overflow. Since there is no gasket between the nut and the inside of the external overflow and the water level rises above the bottom of the bulkheads.. I think that's where the leak is coming from.

So my question is... what can I use to seal the nut on the inside of the external overflow? I would think a gasket but I'd rather ask you knowledge people before I make a decision.

Thanks for reading!

[FamilyTank]

I'm in the design phase of my set up. That being said take this with a grain of reef salt.lol I believe you should have 2 washers for each bung with an internal and external box. If no internal box just siliconed in,shouldn't you have your washer between the tank and ext overflow?

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[Bl4ckDr4g0n]

I would expect there to be two gaskets. Since you cant put the gasket against the nut which I would assume is inside the external overflow, I would presume there would be a gasket inside the tank against the flanged side of the bulkhead, and gasket between the external overflow and the tank.

[Ztous]

Gasket can't be on the nut side. It will twist and create a break in the seal. Did you hand tighten or use a tool? Always use a tool to tighten the nut. I can't think of a circumstance where silicone would be appropriate.

Good mechanical design >>>>>>>>> Adhesives.

[Capiross1]

You could look into getting these I don't know if there is an appropriate size for your setup but the 1 inch ones are the same size as standard abs sch40 as you can see there's is orings on both sides


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[mattruggiero]

Ok. just so you guys have a visual. Here is a pic of the back of my tank (older photo but you'll get the idea) and one of the front. I think I also need to seal the nut side of the bulkhead in to keep the water from my external overflow from dripping down the back of my tank... because right now just the nut is responsible for stopping the leak and obviously that isn't working.

There is a gasket on the inside of my tank... the flange of the bulkhead.

Some of you guys are saying I can't put an extra gasket on the nut side of the bulkhead.. so what do you suggest?

Thanks!!

[mattruggiero]

Originally Posted by Capiross1

You could look into getting these I don't know if there is an appropriate size for your setup but the 1 inch ones are the same size as standard abs sch40 as you can see there's is orings on both sides


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Great find!! I'll definitely look into this. Thanks Cap!

[mattruggiero]

By the way... I'm headed out of town shortly and will be back by a computer tomorrow. I'll respond to you guys then. Thanks again for your input!

[Capiross1]

Originally Posted by mattruggiero

Ok. just so you guys have a visual. Here is a pic of the back of my tank (older photo but you'll get the idea) and one of the front. I think I also need to seal the nut side of the bulkhead in to keep the water from my external overflow from dripping down the back of my tank... because right now just the nut is responsible for stopping the leak and obviously that isn't working.

There is a gasket on the inside of my tank... the flange of the bulkhead.

Some of you guys are saying I can't put an extra gasket on the nut side of the bulkhead.. so what do you suggest?

Thanks!!

The picture of the bulkheads I posted has orings one on flange side one on nut side won't that take care of the issue, and I've seen regular bulkheads with gaskets one on each side so if you want to try using the bulkheads you have I'd say get another set of gaskets put a little silicone grease on them so the nut doesn't twist them up when you tighten them


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[Capiross1]

Originally Posted by mattruggiero

Great find!! I'll definitely look into this. Thanks Cap!

Yea like I said just check your hole size I know the 1 inch ones are the same size as regular sch40 not sure on the others


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[Lsufan]

I could be missing something on your setup but If your external overflow is acrylic & being held on by the bulkheads then u should have a gasket sandwiched between the tank & the external overflow. If it is glass & siliconed to the tank then a gasket won't do any good it is the silicone seam that has a leak & the external overflow isn't water tight.

[Lsufan]

If the leak is coming from the bulkheads on the bottom of the overflow where the plumbing goes then they eighther need to be tightened some or u have a bad gasket or bulkhead, but a gasket on the flange side should be all u need on the bulkheads on the bottom of your exterior box

[mattruggiero]

Originally Posted by Lsufan

I could be missing something on your setup but If your external overflow is acrylic & being held on by the bulkheads then u should have a gasket sandwiched between the tank & the external overflow. If it is glass & siliconed to the tank then a gasket won't do any good it is the silicone seam that has a leak & the external overflow isn't water tight.

I've been thinking about what you said.. a gasket between the tank and the external overflow... and I think that will work. I'll give it a shot. Thanks!