Need to seal a hole!

[Clownfish25]

I have a 225 gallon fish tank with a dual center overflow. However the tank also has a hole on either side of the tank driled into the bottom of the tank. The previous owner used the holes as return lines to get flow from the bottom. I need the best way to seal/plug them up. Can I use bulkheads? Or get a peice of glass cover the hole and silicone it down? Please help with advice. Thank you

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[Frankie_Garcia]

One way I did it was with a bulkhead, pvc then end cap that was siliconed. It lasted a year. But I don't know with a tank that big.


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[Clownfish25]

After a year it started leaking on you? How bad? And did you drain the whole tank and repair it?

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[jetajockey]

I have a 120 and several 40b's with bottom drilled holes covered by glass. No problem just silicone around it well on both sides. I suggest laying the glass on the tank and then siliconing around it. Doing it the other way may leave some slight gaps for water to get in.

 

[Frankie_Garcia]

After a year it started leaking on you? How bad? And did you drain the whole tank and repair it?

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Oh no it didn't leak I just upgraded! Haha sorry should have been more in depth


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[PB_Smith]

No problem just silicone around it well on both sides. I suggest laying the glass on the tank and then siliconing around it. Doing it the other way may leave some slight gaps for water to get in.

mmmm, no, siliconing just around the edges is destined to fail in the future.

The safest way to do it would cut a piece of THICK TEMPERED glass that is at least 1" bigger on all sides than the hole, if possible.
Clean all surfaces and then lay a nice coating, 1/8"-1/4" thick of silicone over the entire patch piece and press it into place. There should be plenty to squish out the sides and down to fill the hole, which is what you want. You can easily see if there are any gaps and just smoosh the glass patch around to deal with them. Then smooth the silicone on the underside of the tank so it fills the hole completely like a plug. If you want you could put another piece of glass underneath as well.
Have used this technique a few times with no negative results.
Patched like that it should last the life of the tank.

 

[MICEY]

I would put a bulkhead in with a ball valve on it and connect a hose to it
you could then drain water out of the bottom of the tank where the worst water is when doing water changes

 

[Masoniac]

I would put a bulkhead in with a ball valve on it and connect a hose to it
you could then drain water out of the bottom of the tank where the worst water is when doing water changes

That would work if they decide bare bottom.

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[PB_Smith]

I would put a bulkhead in with a ball valve on it and connect a hose to it
you could then drain water out of the bottom of the tank where the worst water is when doing water changes

In a saltwater reef tank, or ANY tank for that matter, there should not have areas of "bad water", if so then there is inadequate water flow/circulation.
Actually water flow should be such that the bottom layers of water are continuously being circulated to the surface for maximum oxygenation.

 

[Clownfish25]

Oh no it didn't leak I just upgraded! Haha sorry should have been more in depth


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Oh lol, ok thanks

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[Clownfish25]

mmmm, no, siliconing just around the edges is destined to fail in the future.

The safest way to do it would cut a piece of THICK TEMPERED glass that is at least 1" bigger on all sides than the hole, if possible.
Clean all surfaces and then lay a nice coating, 1/8"-1/4" thick of silicone over the entire patch piece and press it into place. There should be plenty to squish out the sides and down to fill the hole, which is what you want. You can easily see if there are any gaps and just smoosh the glass patch around to deal with them. Then smooth the silicone on the underside of the tank so it fills the hole completely like a plug. If you want you could put another piece of glass underneath as well.
Have used this technique a few times with no negative results.
Patched like that it should last the life of the tank.

Ok so i need to cover the entire surface of the glass and stick it down over the hole? Then silicone the edges and silicone the hole? That will last a long time and not crack with the sand and rock over it plus water weight.

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[Clownfish25]

I would put a bulkhead in with a ball valve on it and connect a hose to it
you could then drain water out of the bottom of the tank where the worst water is when doing water changes

I like the idea thank you but i have an easier water change system. Plus i will have sand covering that area in the tank.

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[PB_Smith]

Ok so i need to cover the entire surface of the glass and stick it down over the hole? Then silicone the edges and silicone the hole? That will last a long time and not crack with the sand and rock over it plus water weight.

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If you coat the entire side of the patch piece you should not have to worry about silicone the edges as the entire contact surface will be covered and excess will squish out the edges. Just smooth it up and over the patch. There should also be enough to more or less fill the hole, I just smooth it over for aesthetics and to be certain there are no gaps.

 

[mr_X]

If the glass patch is the same thickness as the tank glass, it will withstand the same weight/pressure. I would use this, and not the bulkhead idea, bearing in mind that you never want to use those holes again. What about a closed loop? You could also use these for drains or returns. If the holes are there, might as well utilize them.....

 

[jetajockey]

mmmm, no, siliconing just around the edges is destined to fail in the future.

The safest way to do it would cut a piece of THICK TEMPERED glass that is at least 1" bigger on all sides than the hole, if possible.
Clean all surfaces and then lay a nice coating, 1/8"-1/4" thick of silicone over the entire patch piece and press it into place. There should be plenty to squish out the sides and down to fill the hole, which is what you want. You can easily see if there are any gaps and just smoosh the glass patch around to deal with them. Then smooth the silicone on the underside of the tank so it fills the hole completely like a plug. If you want you could put another piece of glass underneath as well.
Have used this technique a few times with no negative results.
Patched like that it should last the life of the tank.

How far in the future is it destined to fail, and why? I've got tanks 20+ years old done by this method that haven't leaked a drop yet. I even did this to 12 40b's several years ago and haven't had any issue with any of them. It even made it a little bit easier to remove the patch when one needed to be piped for an overflow.

It works on the same concept as siliconing two pieces of glass together to make the tank. You don't see people putting silicone on the ends of the tank glass and then 'smooshing' them together. I also suggest putting silicone in the underside of the tank to fill the hole, just extra insurance.

I'm sure it could work either way, but the 'smoosh' method seems to be more prone to error in that you'd have to make sure you get a good layer of silicone around the hole under the glass to ensure that it's sealed well.

 

[PB_Smith]

I'm sure it could work either way, but the 'smoosh' method seems to be more prone to error in that you'd have to make sure you get a good layer of silicone around the hole under the glass to ensure that it's sealed well.

by covering the entire patch with silicone and applying it on the INSIDE of the tank will ensure there are no leaks or gaps. If the entire patch is covered with silicone, how in the world could it be possible for it to not be sealed around the hole? Silicone is translucent and it would be very apparent if there were any gaps/voids in the silicone.

With just a bead of silicone around the edge of the patch it would be more prone to lifting and separating over time, plus you would have a blank space between the tank bottom and the patch, a possible cracking failure point for the patch.
The seams of an aquarium are two fold, a layer of silicone between the edges of the glass panels, this is primarily to bond the panels together,
second a bead/seam is applied to the inside gaps, that is for making it water tight.
You don't think I was saying to put it on the outside do you?
NEVER patch an aquarium from the outside, always patch it in a manner that the water pressure will help hold it tight against the glass.

I think maybe you are envisioning something different than what I tried to convey.

and actually putting silicone on the ends/edges of the glass panels and then smooshing them together is exactly how aquariums are made.

 

[crister13]

I would just put a bulkhead in then PVC and cap the PVC. Don't see why or how that wouldn't work.


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[Clownfish25]

I would just put a bulkhead in then PVC and cap the PVC. Don't see why or how that wouldn't work.


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I tried doing it this way but it started leaking 30 gallons in, mayber I over tightend the bulkhead? If I do get it to hold with just a bulkhead, is that going to last?

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[jetajockey]

Yes bulkhead work just fine. Its what you'd use if you piped the system as was originally intended.

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[Clownfish25]

Hey everyone thanks for the advice, I filled it about halfway. The two bulkheads were capped with pvc and were hand tightend. I had to get different rubberwashers which i had to by a couple bulkheads, but shes holding so far. Is there anything else for me to do? How long should the bulkheads last? I have also attached some pictures

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