# Drilling a hole in my fish tank



## mcflyyy (Apr 5, 2008)

Hi all,
I want to run the water into my new 4ft tank via a hole in the bottom of the tank instead of having pipes everywhere, the outflow is a weir type and already has a hole and bulkhead in the bottom. 
My question is this: Do you think that a second hole in the BOTTOM would weaken the glass to much, and should I have my hole drilled in the back of the tank instead?
Cheers,
Mcflyyy


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## Mcdaphnia (Dec 16, 2003)

I would probably return water via the big "hole" at the top of the tank. I did buy a 120 once that came with a return drilled in it. I ended up putting a threaded plug in the return bulkhead. There was just as much piping needed with the second hole, and some of it was more visible hooked up via the return bulkhead fitting.


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## Rick_Lindsey (Aug 26, 2002)

mcflyyy said:


> Hi all,
> I want to run the water into my new 4ft tank via a hole in the bottom of the tank instead of having pipes everywhere, the outflow is a weir type and already has a hole and bulkhead in the bottom.
> My question is this: Do you think that a second hole in the BOTTOM would weaken the glass to much, and should I have my hole drilled in the back of the tank instead?
> Cheers,
> Mcflyyy


Many commercial tanks come with two holes drilled in the overflow (a larger one for the standpipe, and I believe the smaller one is often for the return). Have you verified that the bottom of your tank isn't tempered, though?

-Rick (the armchair aquarist)


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## Mcdaphnia (Dec 16, 2003)

Rick_Lindsey said:


> Many commercial tanks come with two holes drilled in the overflow (a larger one for the standpipe, and I believe the smaller one is often for the return). Have you verified that the bottom of your tank isn't tempered, though?
> 
> -Rick (the armchair aquarist)


Good point. People sometimes assume that if a bottom has a hole already it can't be tempered glass, but that is not true.


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## mcflyyy (Apr 5, 2008)

Mcdaphnia said:


> I would probably return water via the big "hole" at the top of the tank./quote]
> 
> Yes, that would be by far the easiest option. It makes more sense for several reasons. But then I've never been known to do things the easy way
> The tank will be sitting on a large cabinet, with the sump & pump inside and I just like the idea of having a free standing tank with no pipes visible
> ...


I asked our local glazier about this, and he says that if the glass is hardened or tempered there will be a stamp on the glass. Would this be safe to go on as I cannot think of another way to check.

If the glass is OK to drill, would a small hole in it make a huge difference to the strength of the glass though?

Thanks for your help,
McFlyyy


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## Mcdaphnia (Dec 16, 2003)

mcflyyy said:


> I asked our local glazier about this, and he says that if the glass is hardened or tempered there will be a stamp on the glass. Would this be safe to go on as I cannot think of another way to check.
> 
> If the glass is OK to drill, would a small hole in it make a huge difference to the strength of the glass though?
> 
> ...


If there is a stamp on it, it is tempered, but the absence of a stamp does not guarantee that it is regular glass. Anderson Window has been etching a stamp and code on their tempered glass for some time, but they didn't always. Some tank manufacturers use stickers instead and they can easily wear off after a time. There is an expensive tool that uses polarized light to create a moir pattern inside glass. A trained operator can distinguish between regular and tempered glass.


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## mcflyyy (Apr 5, 2008)

Thankyou for your advice, my local glass guy confirmed it is not tempered glass and with the help of an irrigation/water tank specialist I have got my hands on some large diameter bulheads I hope will add to the strength. Will let you know if it all ends up exploding all over my carpet  
Cheers,
Mcflyyy


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## Rick_Lindsey (Aug 26, 2002)

mcflyyy said:


> Will let you know if it all ends up exploding all over my carpet


Best of luck! Don't forget to take pictures of the carnage 

-Rick (the armchair aquarist, who's drill bits are hopefully in transit from hong kong as he types)


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## Mcdaphnia (Dec 16, 2003)

Do it over the glass guy's carpet.


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