Help - how to stop leak at bulkheads of low profile overflow box

[Julius Chen]

I bought a customized low profile overflow box from modularmarine at eBay. A reference photo is attached.

I was able to install it last night, and noticed that there is water leak between the external box and the back of the glass tank. Water shows up from the bottom edge of the eternal box whenever the water inside the external box rises above the bottom of the bulkhead itself. The speed of the leak is about 1 drop of water per 2~3 seconds. And it happens to BOTH bulkheads.

I'd like to ask your advice on what I should do now to stop the leak. Here is list of what I did already:

1. I remember each of the pass through bulkheads came with 2 gaskets. I put one between the internal box and the tank glass, and another one between the external box and the back of the tank. I did notice there is another (the 3rd) gasket inside the internal box and it can't be removed (so I could not have made an installation error re this 3rd gasket).

2. After hand tighten the nut on the bulkheads, I used a plier to turn it 1/4 turn.

3. WhenI noticed water leak last night, I used a plier to give it ANOTHER 3/8 turn (or maybe 1/2 turn, not sure exactly now). But no improvement.

I am scared to risk cracking the glass if I turn further.

FYI - on the 3 drain bulkheads (those going vertical from the external box down to the sump), I only hand tighten the nuts, and then give them another 1/4 turn. No leak at all.

Thanks a bunch!
Julius

 

[Meshmez]

It might be hard to see, but can you tell if the leak is coming from the overflow side or the tank side?

this might sound crazy, but try actually loosening the nut, and then just set it hand tight. you CAN over tighten the bulkhead.

 

[vhuang168]

I believe the 2nd gasket should be under the nut in the external box and not between the external box and the glass.


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[Meshmez]

I believe the 2nd gasket should be under the nut in the external box and not between the external box and the glass.

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the gasket placement in the original post is correct. never put a gasket on the nut side!

 

[vhuang168]

Help - how to stop leak at bulkheads of low profile overflow box

I may be wrong on this.

Can't find instructions from MM but Synergy reef instructions state to put the gasket between external box and the tank.

 

[Julius Chen]

Sorry guys, I mis-spoke. The "..., and another one between the external box and the back of the tank." should have been "..., and another one between builkhead nut and the inside surface of the external box.".

There is water inside the external box. I think this 2nd gasket has to be with the builkhead nut to stop water leaking out of the external box. Put it between the box and tank will not do it, right?

 

[Julius Chen]

I am unable to tell. The outside of the tank and the external box of the overflow touches each other by the pressure of the bulkhead nuts.

I guess I can temporarily seal the two pass through bulkheads so that there is no water in the external box and let water level rises over the bulkheads inside the tank and see if the leak is still there.

I will try tonight.

It might be hard to see, but can you tell if the leak is coming from the overflow side or the tank side?

this might sound crazy, but try actually loosening the nut, and then just set it hand tight. you CAN over tighten the bulkhead.

 

[Julius Chen]

I looked up the instruction Modularmarine gave me before - "The gaskets go between each box and the tank (2 gaskets for each bulkhead)".

I think I put the 2nd gasket in contact with the nut instead. I will check tonight, and this maybe the issue here. Glad I did not try to use plier to screw it all the way last night ;-)

Now, anybody can help explain to me why put gasket next to nut should leak? Intuitively that is the starting location where water can leak.

Sorry guys, I mis-spoke. The "..., and another one between the external box and the back of the tank." should have been "..., and another one between builkhead nut and the inside surface of the external box.".

There is water inside the external box. I think this 2nd gasket has to be with the builkhead nut to stop water leaking out of the external box. Put it between the box and tank will not do it, right?

 

[Meshmez]

I looked up the instruction Modularmarine gave me before - "The gaskets go between each box and the tank (2 gaskets for each bulkhead)".

I think I put the 2nd gasket in contact with the nut instead. I will check tonight, and this maybe the issue here. Glad I did not try to use plier to screw it all the way last night ;-)

Now, anybody can help explain to me why put gasket next to nut should leak? Intuitively that is the starting location where water can leak.

It doesnt matter if it leaks past the nut, because the seal between the glass and box will keep it from coming out. With a gasket on the nut side you can't get the nut tightened correctly. it never matters which end is in the water, gasket always on flange side, nothing on nut side.you should have the gasket between the box and the glass, and the nut should just contact the box. :thumbsup:

flange / gasket / internal box wall / gasket / tank glass / gasket / external box wall / nut

 

[uwntsom]

crap... I installed mine wrong too. better fix it before I put water in. thx meshmez.

 

[uwntsom]

@julius... I added a lid on my outside box for 16. looks nice.

 

[maddhugan]

glad you guys posted this.........

glad you guys posted this.........

I ordered my 36" overflow box from modular marine and I will install the gasket inbetween the box and the tank on both sides and will update the result.

I'm glad you guys posted this at the right time............

 

[uwntsom]

and here's my plumbing so far...

 

[Meshmez]

crap... I installed mine wrong too. better fix it before I put water in. thx meshmez.

I ordered my 36" overflow box from modular marine and I will install the gasket inbetween the box and the tank on both sides and will update the result.

I'm glad you guys posted this at the right time............

:thumbsup:

 

[uwntsom]

yeah no kidding. perfect timing.

 

[Julius Chen]

I drained 8 inches of water, unscrewed the nut, and pull out the gasket in question. Then put it in between the tank and external glass. Hand tighten as far as my hand can go, then use plier to turn another 30 to 40 degrees.

No more leak!

Here are two pictures of the back of tank.

 

[Julius Chen]

By the way, Modularmarine emailed last night that they recommend to apply a bit petroleum jelly to the gaskets. I did not since I fixed my issue earlier of the day.

 

[woodnaquanut]

It doesnt matter if it leaks past the nut, because the seal between the glass and box will keep it from coming out. With a gasket on the nut side you can't get the nut tightened correctly. it never matters which end is in the water, gasket always on flange side, nothing on nut side.you should have the gasket between the box and the glass, and the nut should just contact the box. :thumbsup:

flange / gasket / internal box wall / gasket / tank glass / gasket / external box wall / nut

Well said! Shouldn't this go in a sticky? It's so often discussed.

 

[maddhugan]

I always have this grease

I always have this grease

By the way, Modularmarine emailed last night that they recommend to apply a bit petroleum jelly to the gaskets. I did not since I fixed my issue earlier of the day.

I always have this grease on my hand and it works really well

 

[Meshmez]

Well said! Shouldn't this go in a sticky? It's so often discussed.

It really should be in a sticky on one of the main pages if it isnt already! Its very counter intuitive because like the OP said, it seems you would want the gasket on the water side.



I'm gonna leave Maddhugan's hand grease alone....:lmao::lmao::lmao: