Leaking overflow box....stumped.

[Fin]

That is a nasty chip there. Is the chip on the outside of the tank, or the inside? Looks like the outside to me in the picture. Did you paint the back of the tank and then install the bulkhead gasket? If so, the gasket should be on glass. I also am not liking that gasket. It should be completely smooth.

 

[madweazl]

So I took everything off to get a look at the glass again, and this is the side that leaks. One picture of the side that does not leak...
I’m pretty sure this is the problem, so what do I do?

Looks like you need to remove more paint from the tank for the gasket to seat fully to me but hard to tell from the picture (e.g. so it doesnt contact any paint). As mentioned by another user, I have a gasket between the internal box and glass and another between the external box and glass.

 

[Mandelstam]

Almost seems like it could be that the bulkhead isn't perfectly perpendicular to the glass, and it leaves a slight opening on one side of the gasket even when tightened down.

Edit: Different paint thickness on the side of the hole could lead to same result (backside of tank not parallell to inside).

 

[Jakepen]

Is it possible that you over tightened? I have done pretty bad drill jobs and they didnt leak. I would take it off and reinstall and see what happens. I had this is issue before

That is a possibility, I’ll try later tonight.

 

[Jakepen]

That is a nasty chip there. Is the chip on the outside of the tank, or the inside? Looks like the outside to me in the picture. Did you paint the back of the tank and then install the bulkhead gasket? If so, the gasket should be on glass. I also am not liking that gasket. It should be completely smooth.

Correct, paint is on the outside. I chipped away a good amount of paint, and judging by the ring the gasket left it’s only touching glass, will chip a bit more away to be sure. I thought it was weird that the gasket was not completely smooth, those rings are slightly raised.

 

[Jakepen]

Looks like you need to remove more paint from the tank for the gasket to seat fully to me but hard to tell from the picture (e.g. so it doesnt contact any paint). As mentioned by another user, I have a gasket between the internal box and glass and another between the external box and glass.

Yeah I did add another gasket to the inside of the tank, just be safe.

 

[Jakepen]

Almost seems like it could be that the bulkhead isn't perfectly perpendicular to the glass, and it leaves a slight opening on one side of the gasket even when tightened down.

Edit: Different paint thickness on the side of the hole could lead to same result (backside of tank not parallell to inside).

What would cause the bulkhead to be out of line with the glass?

 

[Mandelstam]

What would cause the bulkhead to be out of line with the glass?

I have no idea really. Never had or played with one of those overflows. But from the symptoms it sounds like the nut isn't pressing down equally hard all around the gasket maybe? So a bulkhead that's not straight or the nut coming on twisted. But it's all guesses.

 

[ReefNoobie88]

Isn’t the gasket supposed to go only on the inside of the tank. If it’s sealed there then water would have only one way to flow, down the bulkhead into the box. That’s how I’ve always installed bulkheads, never had a single leak.

 

[Jakepen]

Isn’t the gasket supposed to go only on the inside of the tank. If it’s sealed there then water would have only one way to flow, down the bulkhead into the box. That’s how I’ve always installed bulkheads, never had a single leak.

I’m not sure. I just followed the directions from Modular Marine.
Took two pictures without the overflow box, and tightened the nut down. The one that leaks, the gasket creeped a lot further down than on the other, possibly because of the chips in the glass, naturally causing the gasket to slide down.

 

[ReefNoobie88]

I’m not sure. I just followed the directions from Modular Marine.
Took two pictures without the overflow box, and tightened the nut down. The one that leaks, the gasket creeped a lot further down than on the other, possibly because of the chips in the glass, naturally causing the gasket to slide down.

Have you tried the gasket on the inside of the bulkhead before sliding it through the hole and tightening the nut down? I think I read somewhere in your original post you did but I wanted to ask. I just purchased their 2400gph with no teeth removable overflow and plan to drill the tank this weekend hopefully.

That chip could certainly be a problem though.

 

[Jakepen]

Have you tried the gasket on the inside of the bulkhead before sliding it through the hole and tightening the nut down? I think I read somewhere in your original post you did but I wanted to ask. I just purchased their 2400gph with no teeth removable overflow and plan to drill the tank this weekend hopefully.

That chip could certainly be a problem though.

Yeah I have.

 

[Jakepen]

Well guys if it is the chip that is the issue, what can I do? Would I be able to purchase a sheet of rubber gasket and cut a new one, with more left over on the outter diameter, would that fix it?

 

[Mandelstam]

Maybe use silicone as a filler? Fill the chip up and when it's cured use a razorblade to cut it flush with the tank?

 

[ReefNoobie88]

Gasket the inside of the tank since that seems to be smooth, the chip side I would silicone to fill any impurities/uneven surfaces. That’s my opinion on it anyways. Silicone and rubber do not bond well, as rubber is meant to expand/contract with changes in temperature and moisture. Using silicone on rubber basically bonds it in place and it will leak in time. Automotive wise unless it’s a paper/fiber gasket you NEVER use silicone on it for expansion/contraction reasons.

 

[Jakepen]

Gasket the inside of the tank since that seems to be smooth, the chip side I would silicone to fill any impurities/uneven surfaces. That’s my opinion on it anyways. Silicone and rubber do not bond well, as rubber is meant to expand/contract with changes in temperature and moisture. Using silicone on rubber basically bonds it in place and it will leak in time. Automotive wise unless it’s a paper/fiber gasket you NEVER use silicone on it for expansion/contraction reasons.

So could I fill that chip with silicone?

 

[ReefNoobie88]

So could I fill that chip with silicone?

Yes, so I would place the gasket on the inside of the tank bulkhead, silicone around the backside of the bulkhead on the outside of the tank, with a bit extra into the chip. Then tighten the nut handtight and a 1/4” turn more. Just remember, if you need to remove it, it’ll be a bit of a pain but doable. Make sure to use the GE silicone 1. Lowe’s or Home Depot for like $5 a tube. Takes a week to cure fully. Wipe down the glass with rubbing alcohol all over the whole and outside, including inside the chip. Proper prep allows for a great bond.

 

[brandolphjr]

I would take the bulkhead out,,clean it and inspected for cracks, stripped thread or bad gasket..then I would clean around the hole removing all paint and silicone, or whatever is on there..use some 1000 grit wet/dry sand paper to help remove debris.. Silicone around the hole,,then install bulk head..tighten it hand tight then about 1/4 turn...after this put a bead of silicone around the edge of glass and bulkhead nut ..let it dry for a least 24 hours..as far for using silicone , they put glass tanks together with it..Most plumber's in my area use silicone on gasket,,and are getting away for plumber putty..as in rubber gasket for sink drains,, toilet tank gaskets, etc.. It gives add insurance not to leak..

 

[ca1ore]

You need to remove more of the paint so that there is clean glass above the chip for the gasket to seal against. If the chip extends beyond the external edge of the gasket then you are going to need to use some silicone sealant. BTW, gasket deforming right under the nut is quite typical and not necessarily a result of the chip. Although I don't do it very often, if you are going to have a gasket right under the nut, it helps to lubricate it with something like DowCorning molycote. Also, it is possible that the external box is not completely flat (acrylic does warp, after all) but you should be able to check that with a T square.

 

[malacoda]

It looks like the chips and micro-cracks around them have actually caused the glass to bulge outward in a few places.

A few 'inward' or missing chips would not affect the sealing ability of the gasket as long as the gasket is large enough to contact smooth clean surface around them.

But outward lumps like that will prevent gasket (and the nut behind it) from seating fully and forming a complete seal.

I would try to smooth them down as much as possible with some 180 or 220 grit grade automotive grade sandpaper. Even some of the already broken bits of glass rub off, leaving some actual little chips/identations, it'll be fine. As long as the gasket is larger in diameter than the chipped area, it will still have a proper, flush surface to seal against.

As for the little circular mold marks on the gasket, you can sand them smooth with the sand paper, but I really doubt they're contributing to the leak ... especially if you have them facing the nut rather than the glass.