# can I use epoxy to seal a thru hull fitting?



## chiroken (Sep 25, 2007)

I've just picked up a 6' 135g tank that is drilled in 1 corner with a 1" hole. The overflow box was plastic junk so I've ripped it out. I plan on just using this tank as a stand alone aquarium without sump. The hole in the bottom pane had a 1" thru hull fitting (pictured on the link I provided below) siliconed in place to drain or something, not sure what its actual function was. The hardware store didn't have a "bulk head" that was solid to prevent water from draining out of the tank.

Can I use 5 minute epoxy to plug the hole and just re-silicone the thru hull back in place? I was thinking to roughen up the inner portion and the top flange near the central hole to better let the epoxy grab hold. Was thinking also to stick something down the fitting to just leave maybe 1/4" of the tube below the flange. Fill'er with epoxy and let the epoxy slightly overflow the top to sort of mushroom.

If so, how long to cure before it can go in water? I was thinking to silicone it in place first, then do the epoxy in case tightening of the fitting changed the epoxied portion at all and popped it out or something. Does it really matter the order? I can save a day and epoxy tonight whereas I can silicone tonight.

How tight to tighten the nut on the bottom of the fitting? Never actually installed any bulkheads myself. Hand tight with silicon on both sides of the glass?

Planning on using GE 1 clear silicon and giving it at least 48hrs to cure before filling tank.

Thanks
http://www.bottompaintstore.com/images/39173.gif


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## b3w4r3 (Dec 14, 2012)

If one end of the fitting will accept pvc pipe I would put a short piece with cap glued on the end. These fittings typically don't need silicone, it should have a rubber washer on one side or the other. The ones in my overflow box have the rubber washer to the wet side. The lock nut should only be tightened by hand just enough to compress the washer slightly.


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## chiroken (Sep 25, 2007)

b3w4r3 said:


> If one end of the fitting will accept pvc pipe I would put a short piece with cap glued on the end. These fittings typically don't need silicone, it should have a rubber washer on one side or the other. The ones in my overflow box have the rubber washer to the wet side. The lock nut should only be tightened by hand just enough to compress the washer slightly.


I would have to take the fitting back to see if there is pvc that will fit within the fitting, not confident it will though. I was looking for any fitting that would fit inside with a cap but not actual pipe (different dimensions). There was no washer, I thought there should have been. I couldn't find a washer but the plumbing section was abit depleted, might have to check elsewhere. I assumed silicone went in between bulkhead and glass as I'm cleaning/re-fitting another big tank and when I removed the fittings there was silicone on the wet side. Guess a bead can't hurt.


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## b3w4r3 (Dec 14, 2012)

Try looking in the sink area of the plumbing supply. They usually have flat doughnut shaped rubber washers for mounting the drain to the sink.

Alternately you could just purchase a bulkhead online which will include the washer. They will accept pvc pipe on both ends (probably yours does too). Just make sure to get the right size for the hole in your tank. 1 inch bulkheads are around $5 to $15. Silicone doesn't really stick to plastic well.


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## chiroken (Sep 25, 2007)

You're right about silicon and plastic, could peel off the silicone that was over the top edge of this fitting. Not sure where to find bulkheads here in town, that really is what I need. Will try Home Depot (not always the same stock as in the US). It came with this thru hull fitting and just trying to figure out how I can use it without wasting it. If I can find an enclosed/solid bulkhead I'll use that. Just regular PVC glue is fine I guess? It's what's used for our house water lines I guess. I do need to find a washer as well.


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## b3w4r3 (Dec 14, 2012)

Pvc glue is safe once cured. Home depot doesn't carry bulkheads, but some people have DIY their own from electrical pipe fittings and sink washers. You could try an automotive parts store, some have rubber that you can cut your own gaskets out of. LFS can usually get you bulkheads too, they may even be able to get you just a washer/gasket for the one you have.

Take the fitting with you to home depot and see which size pvc pipe fits inside it. Then just get a short piece of the pipe, an end cap, and glue it all up.


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## jcabage (May 29, 2012)

You could just get a small piece of glass cut to match the thickness of your tank and silicone it inside over the hole. That could always be removed later if you decide to install a sump as well.


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## Narwhal72 (Sep 26, 2006)

What jcabage said. I have done it with both glass and acrylic but glass makes the better seal. Just put a nice thick bead around the hole in the tank wall completely and lay the piece of glass on top. Then press down to smoosh out the silicone and let cure.


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## chiroken (Sep 25, 2007)

jcabage said:


> You could just get a small piece of glass cut to match the thickness of your tank and silicone it inside over the hole. That could always be removed later if you decide to install a sump as well.


I did think of that. Thought it might be difficult to get a 4x4 inch piece of glass off once siliconed in place. After the fact it would have taken alot less time to just go buy a piece of glass as opposed to searching for bulkheads.

I found a rubber o-ring to use between the top flange and the wet side of the glass. I also found a threaded end cap that will thread onto the bottom portion of the thru hull fitting. I just cut off the bottom 2 inches of the fitting that didn't have threads on it. Plan is to use the original nut on the bottom to hold the fitting in place and then use the threaded end cap with plumber's teflon tape on the threads and that should prevent leaking.


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## Deeda (Oct 12, 2012)

chiroken said:


> Plan is to use the original nut on the bottom to hold the fitting in place and then use the threaded end cap with plumber's teflon tape on the threads and that should prevent leaking.


Be careful using this method. The threads for the bulkhead fitting are not usually the same as they are for pipe thread so you may not get a good seal.

I needed to plug some small holes in the sides of 6 tanks I bought. I bought some Carflex one-piece Liquidtight fittings to use to plug the holes and then used a PVC threaded cap filled with 100% silicone to attach to the male pipe threads of the Carflex fitting. They work great and fit my needs.


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## b3w4r3 (Dec 14, 2012)

Deeda said:


> chiroken said:
> 
> 
> > Plan is to use the original nut on the bottom to hold the fitting in place and then use the threaded end cap with plumber's teflon tape on the threads and that should prevent leaking.
> ...


Plumbing PVC uses tapered threads. It's not that it is different threads, the pitch just changes as you tighten it, forming a better seal. Teflon tape helps in snugging down the cap and preventing leaks.

I'm more concerned that the o-ring might not seal properly. It really needs a flat washer type gasket.


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## chiroken (Sep 25, 2007)

b3w4r3 said:


> Plumbing PVC uses tapered threads. It's not that it is different threads, the pitch just changes as you tighten it, forming a better seal. Teflon tape helps in snugging down the cap and preventing leaks.
> 
> I'm more concerned that the o-ring might not seal properly. It really needs a flat washer type gasket.


Yup, tapered threads on the end cap, will fit tight. Turns out the o-ring fits within the glass hole as the hole is larger than the diameter of the fitting. Was hoping the 0-ring would sit on the glass. I saw some harder rubber flat washers but I don't know how well they will compress (very little). That'll leave 1/8" between the glass and the flange of the fitting to the outside of the washer. I guess if the fitting is snug and the washer is seated flat there should be a good seal either way. I can always fit that space with silicone so it doesn't trap gunk. Was also thinking of putting silicone in the bottom of the end cap so some will smear into the deeper threads with the teflon on the initial threads.


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## b3w4r3 (Dec 14, 2012)

Ya, the gaskets sold with the bulkheads are the same way, they don't go all the way to the edge. A quick google search for "Bulkhead Gaskets" returned a few places selling them for around $2. Is there a reason you don't want to order one online?


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## chiroken (Sep 25, 2007)

b3w4r3 said:


> Ya, the gaskets sold with the bulkheads are the same way, they don't go all the way to the edge. A quick google search for "Bulkhead Gaskets" returned a few places selling them for around $2. Is there a reason you don't want to order one online?


Time. Want this installed quick as I'm under the gun to get this tank going and get fish that are being held for me in!

If I can't find a soft rubber gasket what about just making one? I've got tire tube that I use for various things. Can cut one abit shy of the outer edge of the flange, put a bead of silicone in that slight gap and do the rest as discussed (use the threaded end cap etc)? Can cut it out in 2 minutes and get it done. Wash/rinse the rubber well and that will suck in the fitting nicely.


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## jcabage (May 29, 2012)

If you are going to use silicone, you might as well go buy some glass imo. The last thing you want is something you've rigged up to come apart with 135 gallons of water on top of it IMO.


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## b3w4r3 (Dec 14, 2012)

Well I understand your rush, but finding out something won't work after filled with water will only set you back more. That said the inner tube might work, only way to be sure it try. Just keep a close eye while filling to ensure it's not dripping water (obviously). Don't over tighten the bulkhead either or it will distort the rubber seal. As tight as you can get it by hand is sufficient.


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## chiroken (Sep 25, 2007)

jcabage said:


> If you are going to use silicone, you might as well go buy some glass imo. The last thing you want is something you've rigged up to come apart with 135 gallons of water on top of it IMO.


What do you suggest then to fill the void between the flat washer and the edge of the flange? It will be close to 1/8". Or just leave it? Bulkheads are new to me, not used to having holes in my tanks so I'm figuring it out as I go. Good exercise here as I will soon be re-plumbing a 300g with large sump and there will be several bulkheads involved with that job. Those will be purchased in advance and will be fully the correct components.


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## jcabage (May 29, 2012)

chiroken said:


> What do you suggest then to fill the void between the flat washer and the edge of the flange? It will be close to 1/8". Or just leave it? Bulkheads are new to me, not used to having holes in my tanks so I'm figuring it out as I go. Good exercise here as I will soon be re-plumbing a 300g with large sump and there will be several bulkheads involved with that job. Those will be purchased in advance and will be fully the correct components.


I would just drop the bulk head and use a simple piece of glass and some silicone. It will take all of 1 minute and a couple day's drying time to have it fill-ready. You would be out looking for other parts anyway, might as well stop by the glass shop, spend $5, and be done.

Ps. I got carried away with IMO's in my last post. Wasn't intending to be rude... it was my opinion though! haha. Best of luck on finding the right solution :fish:


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## chiroken (Sep 25, 2007)

No offense taken, always appreciate the help on forums. In hindsight I thought using this fitting would be easier down the road to convert back to a sump system but now I should have just bought a chunk of glass like you say. The stubborn part of me still wants to make this work though


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## chiroken (Sep 25, 2007)

So here's the update....after all the driving and searching I ended up doing what my first thot was - covering the hole with a piece of glass. Went the glass shop to buy a 4x4 inch piece of say 1/4" glass. Figured I could get a chunk for $5. Then I saw the dumpster. Had a thought....wandered over and full of glass pieces including ~ 4" strips. Grabbed a couple and was on my way thinking I could just scribe the glass and snap it into pieces with something at home. Not so easy, guess there's are reason why there is a specific glass cutting tool. Back to the store to get the darned thing for $6 and it works like a charm. As the glass was thin I used 2 pieces. Siliconed the 1st over the hole, then the second siliconed overtop of the 1st and put a good edge around both pieces. Will let cure for a couple of days and fill'er up.


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## jcabage (May 29, 2012)

chiroken said:


> Will let cure for a couple of days and fill'er up.


 =D> :dancing: =D>

Glad to see you didn't lose an arm trying to break that glass... I'm assuming so at least.

Don't forget to get some pictures posted when you start to stock the tank!


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