Drilling existing drain/return larger?

[Maddlesrain]

I recently picked up a couple tanks I'd like to use for a future project. The issue is they both have a small hole, about 1/4", drilled in the bottom panel. Would it be wiser to silicone a piece of glass over this existing hole and drill a new drain and return line, or try to make the current hole larger? What would be the best way to do this without breaking the glass?
Thanks for the advice!

 

[Jason_MrFrags]

I would be careful as the bottoms tend to be tempered. If the holes are that small, perhaps silicon over with glass from the inside if you can get surface cleaned up good.

 

[Maddlesrain]

I would be careful as the bottoms tend to be tempered. If the holes are that small, perhaps silicon over with glass from the inside if you can get surface cleaned up good.

Is there a safe way to tell if the glass is tempered? They're so tiny, I'm not sure what the intended purpose was for them. I thought maybe I could find a tiny bulkhead to seal them, but nothing is small enough!

If the glass is not tempered, should I drill the bottom or try one of the sides?

 

[Harpo]

rumor has it you can use polarized sunglasses to tell if they are tempered. Sometimes the tank manufactures indicate if they are tempered

 

[Maddlesrain]

rumor has it you can use polarized sunglasses to tell if they are tempered. Sometimes the tank manufactures indicate if they are tempered

Unfortunately I have no way of knowing the manufacturer, but I'll try the glasses trick! I've also been thinking of doing a HOB overflow to avoid the stress of drilling, it's just much less appealing to me.

 

[pennied]

I recently picked up a couple tanks I'd like to use for a future project. The issue is they both have a small hole, about 1/4", drilled in the bottom panel. Would it be wiser to silicone a piece of glass over this existing hole and drill a new drain and return line, or try to make the current hole larger? What would be the best way to do this without breaking the glass?
Thanks for the advice!

Well it’s already been drilled, so there’s your answer to whether or not it can be drilled…lol

 

[BaliReefBox]

It could have been tempered after the hole... you can use polarised sunglasses to tell if its tempered or not...youtube has some vids...to make it bigger get a 5mm acrylic template of the hole size you want and tape it in position and off ya go...slow and lots of water with minimal pressure ..good luck

 

[Maddlesrain]

Well it’s already been drilled, so there’s your answer to whether or not it can be drilled…lol

I meant is it possible to drill the existing hole larger. I figured that they are drillable (unless they were manufactured that way for some reason), but I wasn't sure if drilling an existing hole larger was a bad idea vs just starting over.

 

[Maddlesrain]

It could have been tempered after the hole... you can use polarised sunglasses to tell if its tempered or not...youtube has some vids...to make it bigger get a 5mm acrylic template of the hole size you want and tape it in position and off ya go...slow and lots of water with minimal pressure ..good luck

Thank you for the advice! I'll definitely going to do the sunglass test to double check. From reading a little it sounds like I'd mostly let the drill do the work as far as pressure? I've never drilled a tank myself, but figure now is the time to try it.

 

[BaliReefBox]

yeah drill over the existing i just find the template helps with getting started, you can even use thick cardboard folded over as a started guide

 

[pennied]

I meant is it possible to drill the existing hole larger. I figured that they are drillable (unless they were manufactured that way for some reason), but I wasn't sure if drilling an existing hole larger was a bad idea vs just starting over.

 

[Maddlesrain]

I'm not sure why you're being unnecessarily condescending. I asked a genuine question as I've never drilled a tank myself.

 

[Maddlesrain]

yeah drill over the existing i just find the template helps with getting started, you can even use thick cardboard folded over as a started guide

Thank you again for the suggestions!

 

[dadnjesse]

Thank you again for the suggestions!

without a template of some sort your drill will slide all over the place.

 

[GatorGreg]

without a template of some sort your drill will slide all over the place.

I used the drill guide from BRS. Best choice ever

 

[GatorGreg]

I'm not sure why you're being unnecessarily condescending. I asked a genuine question as I've never drilled a tank myself.

This is just my opinion. Just relying on my gut alone here. I would think your chances of busting the glass are greatly elevated if you try to drill out a bigger hole around a smaller hole that’s already there. I could be wrong though

 

[Blue Spot Octopus]

They make hole saw adapters to re drill a hole, I have that tool, let me tell you it will be very difficult to do on glass. I would seal the two holes and drill on the back of the tank were you are suppose to. Or just buy another tank.

 

[BaliReefBox]

diamond hole saws dont use a centre drill...thats why the guide template is a good idea. imo the existing hole wont make any dif..slow and water and you will be fine..........

or smash the glass

 

[Shon]

Enlarge a glass hole

Has anyone drilled a slightly larger hole in place of an existing hole in glass... Ive got a 180 gallon reef ready tank with an internal overflow, but the overflow is drilled for one large drain and two 3/4 in returns. I would like to do a bean animal overflow (and run the returns through the...

www.reef2reef.com

There's a thread on this, I did it and posted about it also. Hope this helps.

 

[Townes_Van_Camp]

You can do it with the diamond hole saw. There is no guide needed. Start at a sharp angle to the glass. Then as you begin cutting slowly increase the drill angle while moving towards 90 degrees.

Still, be careful