Drilling the tank!

[Picogoby]

Hi all,

 

I am about to embark on drilling the back of my DT for overflow pipes. I have 45 degree bulkheads to limit the space needed behind the tank. 
the tank will have 2x 25mm bulkhead one mounted above the other to create a beanie overflow with a gate valve on the lower one. The return will be 20mm divided in the tank to 2 1/4” random flow nozzles. 
my question is What is the minimum distance I can leave between the edge of the glass (top edge), so as to have my return as high up as possible and limit the back syphon when the pump is off?

never drilled a tank before despite having over 20 in my life time, so your help and advice would be greatly appreciated!

 

Richard 

[Picogoby]

2 hours ago, Picogoby said:

Hi all,

 

I am about to embark on drilling the back of my DT for overflow pipes. I have 45 degree bulkheads to limit the space needed behind the tank. 
the tank will have 2x 25mm bulkhead one mounted above the other to create a beanie overflow with a gate valve on the lower one. The return will be 20mm divided in the tank to 2 1/4” random flow nozzles. 
my question is What is the minimum distance I can leave between the edge of the glass (top edge), so as to have my return as high up as possible and limit the back syphon when the pump is off?

never drilled a tank before despite having over 20 in my life time, so your help and advice would be greatly appreciated!

 

Richard 

Bump! Need an answer!!!

[jservedio]

4 hours ago, Picogoby said:

Hi all,

 

I am about to embark on drilling the back of my DT for overflow pipes. I have 45 degree bulkheads to limit the space needed behind the tank. 
the tank will have 2x 25mm bulkhead one mounted above the other to create a beanie overflow with a gate valve on the lower one. The return will be 20mm divided in the tank to 2 1/4” random flow nozzles. 
my question is What is the minimum distance I can leave between the edge of the glass (top edge), so as to have my return as high up as possible and limit the back syphon when the pump is off?

never drilled a tank before despite having over 20 in my life time, so your help and advice would be greatly appreciated!

 

Richard 

 

Drill them as low down as possible (or drill the bottom pane) and use stand pipes to adjust the water level. You can only drill your tank once, but you can hack down a piece of PVC on your chop saw as often as you want to adjust the water level inside your overflow. Don't glue your standpipes into your bulkhead - you need to be able to remove them.

 

The most important thing is to make sure you can actually drill the back of your tank - if it's tempered, don't even attempt it - you will break it.

[Picogoby]

Thanks for your reply!

its not tempered I checked this with the manufacturer, who informs me a few people have asked and successfully drilled their tanks.

the design is pretty set in stone, just want to know what is the closest I can drill to the top edge of the glass for the return?

the back is to have a very low profile weir which is only 3cm from the back of the tank, so drilling the  bottom is not an option.

[jservedio]

23 hours ago, Picogoby said:

Thanks for your reply!

its not tempered I checked this with the manufacturer, who informs me a few people have asked and successfully drilled their tanks.

the design is pretty set in stone, just want to know what is the closest I can drill to the top edge of the glass for the return?

the back is to have a very low profile weir which is only 3cm from the back of the tank, so drilling the  bottom is not an option.

 

The bulkheads can be as high as you want them to be, within reason. As long as they are low enough where you can fit all of your overflow box plumbing and still maintain a water level in the overflow box that is lower than the weir level and that the "bridge" of glass above the overflow hole is wide enough not to be easily cracked you are fine. I wouldn't get within 2" of the top of the tank, but you could probably push it a little further if your tank had thicker glass.