imperfect hole in glass for bulkhead.. how to prevent leak?

[FishPersonFL]

Hi
I recently posted on how to stop leak from new tank bulk head for shadow overflow. Attached are two pics. I see after I took off the overflow that I have the imperfections you can easily see. all defects of course are on the inside of the tank. The largest on the top and the left (at 9 oclock). Second pic shows how gasket will fit over the hole. It does cover easily with fair room to spare.
I jsut cut away the black film around the hole thinking that was cause of the leak (which still it could have been).
At least it's almost no pressure on teh hole, since its at top fo the tank. and no defects in bottom half really on either of the holes. I mention that since the overflow will be holding on the the holes, gravity can pull it downwards.

**I was reading for a similar situation, except the hole was on bottom of the tank, a suggestion was to silicone around perimeter of outside of the hole and affix the outside gasket to that to prevent any leaks that way. I was wondering should I do this to the inner gasket as well? The overflow has two gaskets per hole. One on the inside of tank wall and one on outside. the member suggesting this said it works for him/her.
I'm thinking that's the thing to do or no? What shoudl I do (hopefully not too difficult)
TIA

 

[FishPersonFL]

I'm thinking this now: even if I dont 'fix' this, the inner gasket is preventing the water from passing through the outter diameter of the gasket to the outside diameter of the hole, or to the edge of an imperfection. If water reaches teh imperfection, then it goes through the hole, between the outter diameter of the pipe going through the hole and the glass hole itself. Then that water hits the outter gasket that is around a perfect hole. The outter gasket prevent any small amount of water passing through it. Reasoning it out, as long at there's no imperfections on the out side side of the hole then I should have no leaks, esp when there is little pressure here. no?

 

[Red_Beard]

I would lean that way. But, i would fill it up and test it w tap water first to make sure though.

 

[FishPersonFL]

I would lean that way. But, i would fill it up and test it w tap water first to make sure though.

Thanks for that.. yes I'll need to leak test again.
SHoudl I silicone the inner gasket? will that just rinse away over time anyhow?

 

[SteveMM62Reef]

If the bulkhead moves around inside the hole, I recommend putting an “O” Ring around the Bulkhead, to prevent it from shifting when installing it. Is there anyway you could use a sturdy pair of gloves and Garnet Sandpaper, to smooth out the chips in the glass? I’d be concerned about them spreading and making a crack.

 

[vetteguy53081]

Thanks for that.. yes I'll need to leak test again.
SHoudl I silicone the inner gasket? will that just rinse away over time anyhow?

While not a typical practice, I always apply a thin bead of silicone on both sides of gasket as an insurance policy

 

[Red_Beard]

If you dont plan on taking it out ever you could silicon that gasket on. Just smear up the back side and install the bulkhead like you normally would. Only dwonside is that once you do if that hasket comes off when you take it apart and it leaks you will have to scrape it 100% clean and try again. Silicon wont stick to silicon so no do-overs.

 

[Reefering1]

Maybe put some silicone on the glass and use a credit card or something to scrape it flat, then let it dry. providing a flat sealing surface. Rather than putting it on ther gasket, that way it comes apart easy and clean for the future.

 

[Reefering1]

I'm thinking this now: even if I dont 'fix' this, the inner gasket is preventing the water from passing through the outter diameter of the gasket to the outside diameter of the hole, or to the edge of an imperfection. If water reaches teh imperfection, then it goes through the hole, between the outter diameter of the pipe going through the hole and the glass hole itself. Then that water hits the outter gasket that is around a perfect hole. The outter gasket prevent any small amount of water passing through it. Reasoning it out, as long at there's no imperfections on the out side side of the hole then I should have no leaks, esp when there is little pressure here. no?

The problem with this is that the water can seep between the threads of the bulkhead/nut

 

[FishPersonFL]

The problem with this is that the water can seep between the threads of the bulkhead/nut

That is inside the outter overflow box.
it can seep if not a good seal on either side of the outter gasket. That is after making it through the inner gasket barrier
To answer the sand paper idea. Good idea. But there are no cracks/points to extend a crack. They are smooth rounded edges that i might make worse with my newbiness at trying to smooth it. Im sure all holes have some tiny defects with same possibility of growing.

 

[FishPersonFL]

If i silicone ceement the outter oring its
Nkt going on another oring. If i have to remove and replace it it doesnt seem like it would be difficukt to scrape off the sikicone with a blade (?).
maybe the sikicone grease idea and flatten it out instead ( ?)

 

[FishPersonFL]

Maybe put some silicone on the glass and use a credit card or something to scrape it flat, then let it dry. providing a flat sealing surface. Rather than putting it on ther gasket, that way it comes apart easy and clean for the future.

I misread that at first. I thought you talked about two gaskets on one side somehow
Your idea makes sense. But then is a dry silicone cement a good surface against the gasket to seal it(?).
no sikicone in my case might be besr. So maybe its best to leak test without anything extra. And see how that goes.

 

[FishPersonFL]

Actually ill try it with suoer light coating of silicone grease

 

[Reefering1]

Grease!?! That doesn't sound reef safe. I meant like silicone aquarium sealant. Put a dab of aquarium safe sealant on the rough surfaces, where the flakes of glass are missing, covering all defects. Then use a sturdy piece of plastic and scrape across the entire hole/sealing surface in 2 perpendicular passes.(like spackling drywall with a drywall knife) wipe away excess sealant. The idea is to fill in the low spots in sealing surface. The rubber gasket will have a flat surface to seal against rather than half the sealing area in damaged areas

 

[FishPersonFL]

Grease!?! That doesn't sound reef safe. I meant like silicone aquarium sealant. Put a dab of aquarium safe sealant on the rough surfaces, where the flakes of glass are missing, covering all defects. Then use a sturdy piece of plastic and scrape across the entire hole/sealing surface in 2 perpendicular passes.(like spackling drywall with a drywall knife) wipe away excess sealant. The idea is to fill in the low spots in sealing surface. The rubber gasket will have a flat surface to seal against rather than half the sealing area in damaged areas

That's a really good idea to fill it in like you said.
And yes, I was going to consider the silicone grease, same as is used to for oring seals. Im not doing that anymore after your idea :-D

 

[Reefering1]

The sealant will seal against the glass and fill in the low areas for the gasket to push against. I've done this with jb weld on pitted engine blocks to provide flat sealing surface. If its good enough for head gaskets and water pumps, itll work on this no pressure application. I do like the idea of sliding a o-ring over the threads to tighten up to slop of the bulkhead in the hole, so it doesn't shift when tightening., keeps it centered. I've cracked a bulkhead before by accident bumping drain pipe while working in sump. Really was glad to just drain overflow and swap bulkhead easily. But my overflow is a 6" square, 30" deep. However, Yours does look easily accessible.

 

[FishPersonFL]

The sealant will seal against the glass and fill in the low areas for the gasket to push against. I've done this with jb weld on pitted engine blocks to provide flat sealing surface. If its good enough for head gaskets and water pumps, itll work on this no pressure application. I do like the idea of sliding a o-ring over the threads to tighten up to slop of the bulkhead in the hole, so it doesn't shift when tightening., keeps it centered. I've cracked a bulkhead before by accident bumping drain pipe while working in sump. Really was glad to just drain overflow and swap bulkhead easily. But my overflow is a 6" square, 30" deep. However, Yours does look easily accessible.

Thank you for that advice. Do i use jb weldon for this (glass chips/pits) or the sikicone cement? I see now why to use the oring. Im getting them today homedepot. Hopefully they have jb weldon.
ill have to be careful applying the weldon or sikicone so it stays only on the defects and not beyond so it doesnt interfere with the gasket seal.
ty!!

 

[FishPersonFL]

The sealant will seal against the glass and fill in the low areas for the gasket to push against. I've done this with jb weld on pitted engine blocks to provide flat sealing surface. If its good enough for head gaskets and water pumps, itll work on this no pressure application. I do like the idea of sliding a o-ring over the threads to tighten up to slop of the bulkhead in the hole, so it doesn't shift when tightening., keeps it centered. I've cracked a bulkhead before by accident bumping drain pipe while working in sump. Really was glad to just drain overflow and swap bulkhead easily. But my overflow is a 6" square, 30" deep. However, Yours does look easily accessible.

Thank you for that advice. Do i use jb weldon for this (glass chips/pits) or the sikicone cement? I see now why to use the oring. Im getting them today homedepot. Hopefully they have jb weldon.
ill have to be careful applying the weldon or sikicone so it stays only on the defects and not beyond so it doesnt interfere with the gasket seal.
ty!!
Is this the weldon to use? https://www.homedepot.com/p/J-B-Weld-0-85-oz-KwikWeld-50176H/303710806

 

[Reefering1]

No jb weld near tank. Use aquarium safe silicone sealant

 

[Reefering1]